What Is Photogrammetry?

What Is Photogrammetry?

For centuries, photogrammetry has played a critical role in our understanding of faraway objects and the Earth’s surface. Its uses have expanded over the years and have led to a powerful range of game-changing technologies in industries like construction, engineering, medicine and much more.

Photogrammetry gathers measurements and data about an object by analyzing the change in position from two different images. It uses things like perspective, advanced processing software and photo analysis to get the job done, but it can happen on the ground or from the air. In this guide, we’ll explain the different types of photogrammetry and how it can be used.

The Basics of Photogrammetry

The process of photogrammetry can vary, but the general idea revolves around gathering information about an object from photos of it. The photos are taken from different locations and angles to allow for precise calculations that help analysts gather the data they’re looking for. Typically, they use things like photo interpretation and geometric relationships to gather measurements. With the data gathered from photogrammetry, we can create maps and 3D models of real-world scenes.

The technology has been around for a long time and has been an important part of a variety of research in the last century. Its principles date back to Leonardo da Vinci’s research on perspective in 1480 — and many theories say it goes back even further. After the invention of flight and World War II, photogrammetric technology really increased, with powerful camera designs and new aircrafts built specifically for aerial photography and better camera positioning. All of the new inventions even put photogrammetry on the moon to map its surface during the Apollo missions.

If we break down the word, we can clearly see all of the parts that make up photogrammetry in play. “Photo” refers to light, “gram” means drawing and “-metry” refers to measurements. Photogrammetry uses photos to gather measurements with which we can create drawings and models.

What Is Aerial Photogrammetry? 

Taking aerial photos is one of the most common approaches to mapping out an area. In this process, a camera is mounted on an aircraft and pointed toward the ground with a vertical or near-vertical axis. As the plane follows its flight path, the camera takes multiple overlapping photos, which are then processed in something called a stereo plotter.

The stereo plotter is an instrument that helps determine elevations by comparing two different photos and conducting the necessary calculations. With the help of photogrammetry software, we can process this information and create digital models out of it.

What Is Terrestrial Photogrammetry? 

These images are taken from a fixed position on the ground with a camera’s axis parallel to the Earth. Data about the camera’s position, such as its coordinates, are collected at the time the photo is taken. The instruments used for terrestrial photography are often theodolites, though regular cameras are sometimes used as well. Terrestrial photogrammetry for surveying typically requires fewer resources and skilled technicians to accomplish, but it may take longer to cover a large portion of land.

What Is Space Photogrammetry? 

Moving out to a larger scale, space-based photogrammetry occurs with cameras either fixed on Earth, in an artificial satellite or positioned on the moon or another planet. In fact, photogrammetry was touted as a key part of space exploration even in the ’60s, and technological advancements have made it even more relevant. It can tell us about cloud patterns, create accurate maps of Earth and gather data about faraway planets.

Types of Photos

Since aerial photogrammetry is one of the most common methods, let’s take a look at how those photos get classified.

Typically, aerial photos will fall under one of two categories:

  • Vertical photographs: These images occur when the camera axis is vertical. So, if you put the camera in an airplane, its lens would point down to the ground for a birds-eye view.

  • Tilted photographs: Though the axis may be nearly vertical, tilts in the aircraft can cause an image to be unintentionally tilted in one direction. Within the category of tilted photographs, we have oblique photos, in which you can see the horizon line, and low-oblique photos, in which there is no apparent horizon. The classification depends on the level of tilt of the camera off of its vertical axis.

The lens of the camera can also offer a range of coverage. For instance, an ultra-wide-angle lens captures a larger field of view than a normal-angle lens. It would gather more of an image in its sights but could create distortion at its edges, depending on the lens and camera design.

When collecting aerial photos, operators capture many images in succession. These images need to overlap with each other, so the image processing software can identify the changes and understand where specific objects are placed. When it can capture those common items, it can more effectively stitch the photos together or gather data about their positions.

What Are the Principles of Photogrammetry?

This process can get complex, but it all comes down to the concept of triangulation. Triangulation involves taking pictures from a minimum of two different locations. These pictures create lines of sight that lead from each camera to specific points on the object being photographed. The intersection of these lines plays into mathematical calculations that help produce 3D coordinates of the specified points.

Triangulation is used in a wide variety of fields, from agriculture to military intelligence, but it is commonly associated with land surveying. Surveyors use theodolites and triangulation to gather the location of a point with the help of angle measurements. Triangulation networks can also help with a surveying system by maximizing accuracy.

It’s actually similar to the way our eyes work and create depth. Depth perception occurs when we see an object from slightly different angles, those angles coming from each of our eyes. Our brains process the two images and make them into a single image that we can comprehend in a process called stereopsis. This whole process is similar to triangulation.

Necessary Features

Some aspects are necessary for any photogrammetric model. These features include:

  • Tie points: Tie points are coordinates that can be linked across multiple overlapping images. Typically, these are features present in both or all of your photos. The tie points help the photo adjust with shared coordinates.
  • Ground control points (GCP): GCPs help to orient the image in relation to the Earth’s surface. They use known coordinates to position the image within the real world.
  • Bundle adjustment: The adjustment helps to remove any distortion within a set of images. It reduces errors from real and predicted image points.

Types of Photogrammetry

While we can classify photogrammetry based on the location of the camera, we can also break things down by the type of photogrammetry being conducted. These types vary based on the kind of data being gathered.

Two forms of photogrammetry that you’re likely to encounter are:

  • Interpretive: Interpretive photogrammetry is all about identifying objects and gathering significant factors from an image with careful and systematic analysis. Photo interpreters gather information about their subjects, such as characteristics and features, by analyzing and evaluating the photos carefully. The job may involve remote sensing technologies. Remote sensing combines photo interpretation with data from remote sensing instruments, like cameras on satellites or aircraft and sonar systems on ships.
  • Metric: In metric photogrammetry, the goal is to find measurements. A researcher may pull specific data and measurements from a photo with the help of other information about the scene.

Metric photogrammetry also covers planimetric and topographical mapping:

  • Planimetric mapping focuses on planes and includes elements outside of elevation, like roads, rivers and lakes. It ignores these topographic features, only focusing on geographic objects.
  • Topographical mapping does the opposite, revealing the shape of the land and its elevations and contours. It shows the Earth’s surface in comparison to a specific reference point, like sea level, and can be used for underwater surfaces, too.

Uses of Photogrammetry

The ways that photogrammetry comes to life can vary widely by collection method, data gathered, industry use and compatible technologies.

Some of the products that come from the process include orthomosaics, digital surface models and digital terrain models. An orthomosaic is essentially a birds-eye view of a terrain that adjusts for distortion and can span wide landscapes. Digital surface models and digital terrain models represent surface levels and elevation. Surface models include buildings and trees, while the terrain model gets rid of all of these features, showing the height of the bare earth.

The most common use for photogrammetry is creating maps out of aerial photos. It is cost-effective and accurate, allowing planning entities like architects, local governments and construction workers to make clear, informed decisions about their projects without spending months scouring the landscape. It is also very detailed and can provide an exceptional level of information about an area.

Photogrammetry makes its mark in an array of industries, from medical research to film and entertainment. Here are some of the places you can find it:

1. Land Surveying

We’ve already discussed the applications of photogrammetry in civil surveying, the results of which are used by many entities, including construction crews, governments, building planners and architects. All of the data gathered from photogrammetry inform them about everything from necessary safety measures to potential project results.

2. Engineering

In the world of engineering, drone photography helps to evaluate sites for construction, as well as  create perspective images and 3D renderings. Engineers can produce images of project results or previews, as well as analyze their current progress.

3. Real Estate

In the digital age, where 80% to 81% of millennials find their homes on mobile devices, creating attractive, accurate listings can significantly improve the buying experience and their understanding of the purchase. Viewers can see the home from all angles and get a clear idea of what they’re looking at.

4. Military Intelligence

Photogrammetry also plays a role in data gathering for military programs. Accurate geo-locational models with low processing times are necessary for understanding a landscape. Aerial imagery and photogrammetric technology can work together to create accurate 3D maps quickly without any human input.

5. Medicine

While you might not think to put the medical field in the same category as land surveying, the 3D models that come from photogrammetric technology come in handy for a variety of health-related uses. It can also work alongside remote sensing technology to help develop diagnoses without invasive procedures.

6. Film and Entertainment

Photogrammetry can play a big role in set design and world-building for a variety of films and video games. 3D modeling can bring unique objects to fruition in a virtual world, like cityscapes for action sequences and accurate historical elements, such as statues and buildings. One popular franchise that uses photogrammetry is the “Battlefield” games, which have an art style that works well with these 3D renderings and recreations.

In addition to world-building, photogrammetry can also assist with designing special effects and real sets.

7. Forensics

Photogrammetry also plays a part in crime investigation. It can help to document and measure precise data about a crime scene and determine what was physically possible. There are also many photogrammetric experts that can assist in the courtroom.

8. Construction and Mining

Project engineers and contractors can use accurate 3D models to monitor and plan their worksites. The information from a photogrammetric model can help create a smart worksite with sensors and safety features that improve the environment. These models work in tandem with connected vehicles.

9. Sports

Analyzing athlete movements can help coaches and researchers understand more about their activities. They can develop virtual training systems and learn about the physical effort that players expend by tracking their body movements. Topographical maps also come in handy for outdoor athletes, like hikers, mountain climbers, skiers and snowboarders. Mapping remote areas is often easier with the help of photogrammetric technology.

10. Agriculture and Forestry

In agriculture, aerial photos can offer insights into soil quality, irrigation scheduling, nutrition and pests. Farmers can adjust their planting schedules or adjust irrigation and fertilizers with this information. They can also use photogrammetry when assessing growth and crop damage after storms or floods.

Researching and managing forests becomes significantly easier with the help of photogrammetry. It can produce models to analyze various aspects of a forest, like timber volume and height, to better understand the development of a forest.

Work With the Data Prep Experts at TOPS

If you work in an industry that could benefit from photogrammetry or have another need for 3D modeling and photogrammetric data, Take-Off Professionals can help you get it. Here at TOPS, we create detailed and accurate surface models to help improve your work. Aerial photogrammetry is one of the fastest methods we use, which makes it especially helpful if you find yourself in a time crunch.

Data are our specialty, and we can assist with several tasks, including drone data point surface modeling, topographic file generation and custom photogrammetry services that meet your specific needs. Reach out today to learn more about how TOPS can take your project to the next level.

Guide to Cut and Fill Maps

Guide to Cut and Fill Maps

The processes involved with building roads, railways and canals often involve adding or removing large masses of dirt and stone. This addition and removal of mass is called cut and fill in the excavation industry. Cut and fill is a common process where the movement of the earth is handled in a logical manner.

The goal of cut and fill is ultimately to conserve energy and maximize the use of existing materials to avoid bringing in or shipping out dirt mass. While common, it can be an exhaustive process — moving earth takes a great deal of labor, and mistakes can lead to costly rework. To avoid such problems, project planners use detailed and intelligent cut and fill maps, providing exhaustive plans to help guide excavation teams to the most efficient use of mass and labor.

What Is Cut and Fill?

So what exactly does cut to fill mean? Cut and fill excavation is also known as excavation and embankment. It’s a process where excavators move and place volumes of material to create optimal terrain for a road, railway or canal. The two terms are defined as follows:

  • Cut: Earth that is removed from an area is considered “cut” or excavated earth.
  • Fill: Earth that is brought into an area is considered “fill” or embankment earth.

When railways, roads or canals are dug out, the cut material is pushed to fill out nearby hills and embankments. This process is usually accomplished with earthmoving equipment. Bulldozers and excavators remove land from cut locations and transfer it to dump trucks, which carry it to fill locations. Once the land is transferred to the fill location, the filled earth is compacted with a roll-style or plate compactor.

This compacting process removes air before any construction takes place. It’s essential, as it prevents the earth from moving and settling during or after the construction process, which can damage the foundation and building features.

loader being used to pick up fill

In cut and fill excavation, the ultimate goal is to conserve mass as much as possible. Having more cut than fill results in project managers needing to find somewhere to dump excess rock and soil, while having more fill than cut results in the manager needing to bring in dirt from another location. Both of these outcomes result in extra material, labor and equipment costs. To avoid bringing in or removing excess mass, cut and fill processes are planned in a way to keep cut mass and fill mass approximately the same.

While effective at conserving mass, cut and fill is an expensive process. The cost of this kind of excavation increases as more land is moved and more equipment and labor are needed to do so. To help maximize the use of earth, equipment and labor, site planners often use what is called a cut and fill map.

How Are Cut and Fill Maps Used?

When they’re planning areas where cut and fill is required, designers create drawings called cut and fill diagrams. These diagrams illustrate all the areas where cut or fill are required. Such maps are generated by taking highly precise measurements of the existing topography and elevation, then overlaying a map of the desired topography. In these maps, cut and fill are defined as follows:

  • Cut: Areas where the existing elevation exceeds the desired elevation have the “cut” material.
  • Fill: Areas where the existing topography lies below the desired elevation line are the “fill” spaces.

Cut and fill maps are typically created in two varieties. The most basic maps utilize 2-dimensional diagrams, while more modern solutions use 3-dimensional modeling software. These two options are explained in more detail below:

  • 2-dimensional diagrams: At their most basic, cut and fill diagrams show a location along an X-axis with a positive or negative Y-axis, quantifying the amount of cut or fill with a negative or positive number, respectively. Since land exists in three dimensions, these diagrams must be created for multiple cross-sections of the landscape at regular intervals.
  • 3-dimensional diagrams: 3-dimensional maps are more modern solutions for cut and fill excavation projects. The terrain is first measured using accurate surveying equipment, and the data points are used to create a software-generated model of the terrain. Once the base model is complete, the planner creates a model of the desired terrain and lays it over the existing terrain model to identify the cut and fill areas in three dimensions. Software models may highlight cut vs. fill areas with different colors that vary based on value ranges.

Choosing to use a 2-dimensional model over a 3-dimensional one should depend on the level of accuracy required for the project. Smaller-scale projects with limited cut and fill needs may not require more than 2-dimensional diagrams. Larger and more expensive projects, however, will usually require the accuracy provided by a 3-dimensional diagram. Beyond this difference, the ability to use one type of diagram over another depends on access to the site and equipment availability.

Terrain Features in Cut and Fill Maps

Cut and fill maps contain many of the same terrain features as traditional maps, though they often also include elevations for the purpose of calculation. Some of the common terrain features included in cut and fill maps are detailed below:

  • Hill: A hill is defined as an area of elevated ground where the ground rises at a slope. Hills are shown on maps using contour lines that form concentric circles. The closed circle that’s smallest represents the hilltop.
  • Saddle: A saddle is a low point between two points of high ground. It may appear as low ground between two hills or a break or dip along a ridge crest. This feature is typically represented on the map with an hourglass shape.
  • Valley: A valley appears as a long groove in the land and usually contains a stream or river flowing through it. On a map, valleys are usually represented by contour lines in a U or V shape with the closed end pointing upstream. Draws are less prominent versions of valleys and are notated in the same way.
  • Ridge: A ridge is an area with steep slope and high ground on one side. Usually, ridges will be shown with contour lines forming in a U or V shape with the closed end pointing away from the higher ground. Sometimes, spurs form from ridges, appearing as continuous lines of higher ground jutting out from the ridge. They’re noted similarly, though they may affect the shape of the ridge.
  • Depression: Depressions are low points or sinkholes in the ground. Maps usually show depressions only if they are significant enough in size, and these features are notated by closed contour lines with tick marks pointing to lower areas.
  • Cliff: A cliff is a sudden drop-off, appearing as a vertical or near-vertical change in elevation. Cliffs usually appear as contour lines being drawn extremely close together or on top of one another.

From the complete map, cut and fill can be planned around existing topographical features. Commonly, a map with these features may be used as a base, with the final project laid over it to determine areas of potential cut and fill. Once initial plans are made, cut and fill plans are added based on the topographical features.

How to Calculate Cut and Fill

So you’ve determined that you’ll need to use cut and fill excavation in your project, and you have an idea of what method you’ll be using. How do you calculate cut and fill area so that you can plan out the labor and calculate your project costs? The calculation method depends largely on the method you’ll be using in your project.

calculating a cut and fill map

A number of software products are available for generating cut and fill maps, and many of them automatically calculate and optimize cut and fill projects. However, if you’re using more manual methods, a manual calculation may be required. A variety of calculation methods are used to calculate cut and fill values, and some of these methods are detailed below.

1. Cross-Section Method

The cross-section method of calculation is a common method used with the 2-dimensional method of mapping. With this method, cross-sections of the existing and proposed land levels are measured at regular intervals across the site. The cut and fill area is determined for each cross-section, then adjacent cross-sections are compared and the averages of their cut and fill areas are multiplied by the distance between them. This is done for each adjacent pair of sections, then the total volumes are added together to create the complete cut and fill volumes for the project.

The cross-section method of calculation is considerably more time-consuming than automatic methods of calculating volume, and the accuracy of the method depends on the distance set between sections. Closer sections result in greater accuracy but take longer to calculate, while further sections are less accurate but take less time to calculate.

2. Grid Method

The grid method of calculation involves drawing a grid onto the plan for the earthwork project. For each node of the grid, determine the existing and proposed ground level and calculate the cut or fill required. Once the cut or fill depth is calculated, multiply the value by the area of the grid cell. Do this for each square of the grid, then add the volumes together to determine the total cut and fill volumes for the project.

Like the cross-section method of calculation, the grid method takes time to implement and is significantly more time-consuming than any automatic systems. Additionally, the accuracy of the grid method depends on the size of the grid cell. Larger cells take less time to calculate but are less accurate, while smaller cells are more accurate but take more time to calculate.

3. Automated Methods

If you’re using an earthwork software, you may not need to use one of the manual methods above. Instead, the software will run the calculations for you. It should be noted that these software systems are faster but not inherently more accurate — for example, some software calculations are based on high-density versions of the cross-section or grid methods. However, automated systems often use more sophisticated calculation methods, such as the triangular prism method.

The triangular prism method is a common calculation method for earthworks, and it’s favored for its excellent accuracy. However, it must be completed using software due to its technical complexity.

The triangular prism method starts by triangulating the existing terrain to create a continuous surface of connected triangles. The same method is used to model the desired terrain. Once both surfaces are complete, the triangulations are merged to create a third triangulation. Once merged, the cut and fill is calculated by taking the volumes of the generated triangles and adding them together. Because of the excellent representation of both the existing and desired terrains, this method presents an excellent representation of volumes for cut and fill projects.

Work With the Data Preparation Experts

The cut and fill process is an extremely useful process for excavation in residential, commercial and roadwork projects. However, while cut and fill makes use of existing terrain, it requires detailed planning to be as effective as possible. To accomplish this goal, project planners need detailed cut and fill maps — that means they need survey equipment to get terrain information and software to process and visualize data in a meaningful way. Take-off Professionals can help.

Take-off Professionals prepares 3D models and performs related services for a wide variety of industries, from commercial construction to civil engineering projects. Our innovative data services are available to help take your terrain data and turn it into meaningful models that you can use for your next cut and fill project.

TOPS works with a wide range of systems, so we can provide services to as many companies as possible. We work with data from  Carlson, Leica, Topcon and Trimble equipment and can provide models in any format you need, whether your engineers use Civil 3D, MicroStation or another design software. We can even work with multi-brand fleets.

When you work with us, you can trust our decades of knowledge and experience as well as our innovative GPS and 3D machine control services technology. With our tools and services, your business can gain detailed insights into your project to help make the most of your cut and fill terrain.

Want to learn more about our models and how they can help on your next cut and fill project? You can get in touch with our team of data preparation experts right away by completing our online contact form or calling us at 623-323-8441.

Guide to 3D Modeling

Guide to 3D Modeling

Technology is transforming nearly every industry, and construction is no exception. One form of tech that has recently had a substantial impact on the construction industry is three-dimensional (3D) modeling. 3D models have a major role in modern construction projects, as they can improve productivity and ease of work.

3D modeling for earthworks and machine control can increase equipment operation accuracy, enhance worksite efficiency and reduce costs, among other benefits. So, how does this technology work, and how can you apply it to your next project?

What Is 3D Modeling?

The term “3D modeling” refers to the process of creating a three-dimensional representation of an object using specialized software. This representation, called a 3D model, can convey an object’s size, shape and texture. You can create 3D models of existing items, as well as designs that have not yet been built in real life.

In construction, 3D models of a worksite can be used for machine control. These replicas incorporate the points, lines and surfaces that make up the physical environment. They use coordinate data that identifies the location of horizontal and vertical points relative to a reference point. Due to these spatial relationships, you can view the representation from various angles.

Machine control uses various positioning sensors to provide machine operators with feedback on things like target grades and bucket or blade position. The machine operators can reference the 3D model to ensure they are completing work accurately. GPS technology enables workers to locate the replica’s points in the field, and sensors on machines tell them where they are relative to the model’s points.

These control processes help crews translate the 3D model into reality by guiding equipment to construct the lines, points and surfaces precisely as described in the representation. Teams may also use 3D models for project, design and environmental compliance reviews. These models also help during pre-bidding, allowing contractors to test out various designs and communicate ideas.

The History of 3D Modeling

The methods and technologies used today for 3D earthworks modeling would not exist without developments in civil surveying and various types of 3D modeling.

You can trace the history of 3D earthworks modeling back to ancient times. Ancient Egyptians constructed the pyramids with early surveying techniques and used geometry to re-establish farmland boundaries after flooding along the Nile River. In ancient Rome, civil surveying became a recognized profession, and surveyors created measurement systems to evaluate and create records of conquered lands.

Euclid, who is known as the founder of geometry and lived in ancient Greece, developed ideas that inspired many modern surveying and 3D modeling techniques. Many years later, in the 1600s, French mathematician Rene Descartes invented analytic geometry — also called coordinate geometry — which is foundational to 3D earthworks modeling.

Moving forward to the 18th century, European surveyors discovered they could use various angle measurements taken from different areas to identify a precise location — a technique known as triangulation. New surveying tools, such as measuring wheels, circumferentors, Kater’s compasses and Gunter’s chains, began to gain popularity. Meanwhile, English mathematicians James Joseph Sylvester and Arthur Cayley developed matrix mathematics, which is what enables today’s computer-generated images to display reflections or light distortions.

Later, surveyors began to use steel bands and invar tapes. These tools eventually gave way to technologies such as electromagnetic distance measurement (EDM) and global positioning satellite (GPS) equipment. Surveyors switched from compasses to theodolites, which measured horizontal and vertical angles using a rotating telescope. They then transitioned to using total stations, which are electronic transit theodolites equipped with EDM technology. These advancements enable them to measure both angles and distances.

Then, the first commercially available computer-aided design (CAD) systems — which turn survey data into visual representations — were released. The first 3D graphics company, Evans & Sutherland, appeared in 1968. Over the next several decades, CAD programs became more advanced and more widely available.

In the machine control field, users began shifting from the use of survey stakes — which surveyors manually set up, and machine operators read visually — to 3D modeling. Various technologies came together to enable 3D earthworks modeling, including:

  • CAD, which turns survey data into a 3D model.
  • GPS, which allows engineers to pinpoint precise locations.
  • Light Detection and Ranging (LiDAR), a remote sensing technology that uses a pulsed laser to measure variable distances.
  • Aerial photogrammetry, which enables engineers to extract topographical data from aerial photographs taken by drones.
  • Point-cloud modeling, which involves using laser scanning technology to create a set of three-dimensional data points used to create a model.

what are 3d models used for

What Are 3D Models Used For?

3D replicas are a prevalent form of technology, but what industries use 3D modeling? Many sectors use 3D modeling for numerous purposes. Some concepts include:

  • Planning buildings using architectural visualization.
  • Giving 3D tours in the real estate sector.
  • Creating video games and movies.
  • Conducting academic research.

Models have several uses in construction as well, and new techniques are always emerging. Here are a few ways 3D models are used in construction:

1. Machine Control

3D modeling enables more accurate, efficient and cost-effective machine control. Instead of using traditional survey stakes, machine operators can see the job site on a screen while in the cab. A system of sensors guides the machine based on the 3D model’s measurements.

Equipment such as excavators, backhoes and bulldozers are equipped with on-board computers, and the blades and buckets include GPS devices. You can either set up a GPS base station at the worksite or subscribe to a GPS service. Whichever system type you choose, it will communicate with the receivers on your machines.

The 3D model is referenced to GPS coordinates and loaded onto your equipment’s on-board computers. These computers can then communicate with GPS receivers and machinery controls. As the device moves throughout the site, the GPS records where it is located at all times. As the blades and buckets on your machinery move, the GPS pinpoints their position.

The computer can automatically adjust the blades or buckets to the required excavation depths or surface elevations. This ability enables smooth, accurate grading of roads, sidewalks and parking lots and more.

2. Site Layout

3D models can also be useful for communicating site layout, including the location of utility equipment and landscape elements.

You can map the location of electrical equipment, for example. That can include electrical service slabs, light poles and connections for signs, kiosks, decorations and other electrically powered elements. A 3D model helps electricians set these connections up quickly and accurately.

You can also use 3D mapping technology to map other utilities, including gutters, water and wastewater piping, natural gas lines and more. Charting the layout of utilities gives crews more confidence about their placement and provides them the information they need to place this equipment at any time.

A 3D model can also include elements such as landscaping, curbing, benches and nearly any other site feature. Accessories such as benches and playground equipment require a base and connection. Knowing where these elements will go can enable crews to prepare them earlier in the process and avoid re-digging later.

3. Progress Reports and As-Builts

3D models can also be useful for communicating project progress and creating as-builts, which are revised drawings submitted at a project’s completion. You can gather new data throughout an assignment to create updated 3D models, showing what the site currently looks like. A 3D model created after a project ends can be used throughout the lifecycle of the facility for purposes such as maintenance, operations and asset management.

construction workers discussing project

Benefits of Using 3D Models for Earthworks

Using 3D models for earthworks and machine control can provide numerous advantages, including:

  • Increased plan accuracy: Creating 3D models uncovers conflicts, inconsistencies and other issues in plans before construction begins, which reduces rework and costs.
  • Increased accuracy in the field: Because the machines have the same data the surveyor does, machine operators have an easier time following project plans. Workers won’t have to rely solely on contours when navigating a worksite. The 3D replica’s surface is also built to the landscape’s actual vertical and horizontal geometry.
  • Lower surveying costs: Using 3D modeling eliminates the need for ongoing grade checking, which reduces surveying costs. Having lower surveying costs can help you win more jobs and earn higher revenue over time. The additional money can also allow you to upgrade equipment and hire employees as your company expands.
  • More efficient machine operation: Machinery operates more efficiently because it moves precisely according to the 3D model’s measurements. 3D modeling helps you accomplish more with your equipment in less time. The increased efficiency also reduces fuel, repair and maintenance costs.
  • Lower raw materials costs: 3D modeling techniques help you hit the mark the first time around and use materials more effectively. This enhanced productivity reduces raw materials costs because you’ll need fewer supplies for each job. This benefit is sustainable and cost-effective.
  • Reduced labor costs: With 3D machine control modeling, many of the machine operator’s duties are automated, which helps them work more quickly and make fewer errors — this quality increases individual worker efficiency, reducing labor costs.
  • Improved communication: You can use 3D models to communicate project information in an approachable, visual way with various stakeholders. If everyone has a common understanding of the material, they’ll have a smoother time sharing ideas and suggestions.
  • Increased number of uses: You can set up the data once and then use it for various purposes, including grading, utilities and hardscaping. You can also make adjustments to the information as needed for subsequent assignments.
  • Reduced project costs: Using a 3D model can reduce project costs by a total of four to six percent, according to a report by the U.S. Department of Transportation’s Federal Highway Administration. In earthmoving alone, 3D models can increase efficiency by 15 to 25 percent.

Request A Free Quote

How Are 3D Models Created?

To create a 3D model, you must first gather survey data. You can accomplish this by using various technologies, including LiDAR and aerial photogrammetry. The initial survey records the locations of physical features and key points, which serve as a baseline. You can then scan the area using LiDAR technology to create data point clouds representing the physical components of a site. These point clouds combine with 3D modeling software to build the 3D representation.

When Take-Off Professionals receives the survey data files for a project, we first ensure we have all the necessary information about the job requirements and the scope of work for which our customer is responsible. We then build the 3D model based on the plans we receive. During this process, we adjust errors in the designs and take notes about potential changes.

Once we have completed the 3D model to plan, we alert the engineers to any areas of concern and propose fixes as needed. We continue to revise the model and suggest changes until every detail is correct.

To begin a 3D modeling project, we need three things:

  1. CAD files: You can ship us your CAD files or upload them to our site. We can use various file formats, including industry-standard formats such as .DWG and .DXF within AutoCAD, plus numerous proprietary formats. We can process any kind of CAD package from Carlson Construction, AutoCAD, Micro Station and others.
  2. Paper plans: We also need either physical paper plans or scans of paper plans. You can upload scanned files or send them to us on a CD. Keep in mind that it is often cheaper to ship rather than scan.
  3. Work order: You will also need to fill out a work order, which will include details about the project’s scope. You can submit a work order through our website.

Some of the elements that may be included in a 3D model for machine control, depending on the project, include:

  • Parking lot surface
  • Roads with vertical and horizontal alignment information
  • Subgrade road model that extends beyond the back of the curb
  • Large islands and building area curbs
  • Small island curbs with grading
  • Building pads, including blow-ups if requested
  • Retention and sheet grading areas
  • 2D linework of utilities or full 3D utility layout
  • Existing conditions
  • Points for the layout of objects built for the surface, such as buildings and curbs

company working with 3D modeling expert

Work With a 3D Model Expert

At Take-Off Professionals, we create approximately 1,000 machine control models for our clients every year. We employ a team of engineers and technical staff who are experts in building 3D models for the construction industry, and we don’t use subcontractors like many of our competitors do. We have groups working across all four major time zones in the U.S. to ensure we’re always there for our clients.

We’ve been in business for more than two decades and have established a reputation for timeliness, accuracy, attention to detail and excellent customer support. We’ve also created an exclusive platform that our clients can use to upload their files in a secure, user-friendly environment. This additional measure ensures placing a work order is fast and easy.

Learn more about how our data and modeling services can help you win more bids, reduce your costs and complete projects accurately and efficiently by contacting us today.

Using 2D or 3D for Your Site Models

Using 2D or 3D for Your Site Models

Modeling is essential in the construction industry for planning projects, communicating ideas and ensuring work gets done correctly. Construction professionals have used two-dimensional (2D) site plans for these purposes for some time, but more recently, three-dimensional (3D) modeling has emerged as an updated approach. Which should you use for your next project?

What Is the Difference Between 2D and 3D Modeling?

2D and 3D modeling involve similar processes, and you can create both 2D and 3D models using computer-aided design (CAD), a set of software tools that assists designers in creating virtual models of structures, machines, components and other objects. However, 3D modeling takes things a step further by adding another dimension, as well as more information and capabilities. What is the difference between 2D drawings and 3D models?

2D Modeling

2D modeling involves creating blueprints, drawings and plans in two dimensions. These documents can describe the basic layout of a site, and where objects are placed, but they don’t include the dimension of depth. These 2D plans can be created on paper or in computer programs that are designed for creating models in two dimensions.

3D Modeling

The major difference between 2D and 3D modeling in CAD is that 3D modeling adds a third dimension. This means that 3D models contain more information than 2D models. They represent the finished site as it will look in real life. 2D models, on the other hand, provide valuable information, but viewers are left to imagine what the final product will look like. 3D models are created in advanced computer programs and incorporate data from Light Detection and Ranging (LIDAR) equipment, the Global Positioning System (GPS) and aerial photogrammetry. 3D models can contain a wide range of information types and can be used for grading, site layout and other purposes, in addition to the uses of 2D modeling.

When to Use 2D for Site Models and Land Surveying

While 2D modeling is an older technology, and many businesses have begun to replace it with 3D modeling, it is still valuable in certain situations. Some of the reasons a company might decide to use 2D modeling include the following:

When You Want a Broad Overview

2D maps are useful for broad overviews of sites. They offer a simple, easy-to-read representation of what your site looks like from above. While they don’t include as much detailed information, 2D plans are useful for conducting high-level inspections and comparing large-scale changes over time. They’re usually high-resolution and zoomable, which allows you to inspect various parts of a project closely. If you want to give someone a simple overview of a site or project progress, you can quickly create a 2D map to meet those requirements.

when are 2d site models helpful

When You Only Need Simplified Measurements

2D plans can also be useful when you just need simplified measurements. You might not necessarily need three dimensions for certain types of measurements, and creating a 2D map allows you to find them quickly and bypass the 3D measurements you don’t need. If you only need a cut and fill number for a certain location on a job site, for example, you can easily find this information with a 2D map. This capability is useful for making quick but accurate decisions in the field.

When Your Equipment Isn’t Compatible

Another reason that companies use 2D models instead of 3D models is that their equipment is not yet able to handle 3D files. As 3D modeling technology becomes more common, this problem is becoming less prominent, but it may still be a concern for certain firms. Some companies may not want to use 3D models at all for this reason, while others might use 3D models in the office but use 2D models in the field on handheld devices that may not work well with the 3D models. It’s important to note, though, that some handheld devices can handle 3D models, and many 3D modeling programs allow you to download models so you can use them anywhere, even if you’re offline. Many sites and computers do have the ability to display 3D modeling, but companies that are using older systems may not want to upgrade to avoid the upfront costs of new or upgraded equipment.

When to Use 3D for Site Models and Land Surveying

3D site modeling offers capabilities that go well beyond those offered by 2D modeling, so it’s a smart choice in many situations. Some of the reasons you might choose to use 3D site modeling include:

When You Want a True-to-Life Visual Representation

3D models represent sites in a way that is true to how they will look in real life. While 2D models can explain the concept behind a plan, it requires some interpretation to determine how the project will look once completed, which can result in different parties having slightly different ideas about a project’s outcome.

3D models, however, show sites exactly as they really look, which ensures that everyone can easily understand the plan and helps keep all parties on the same page. With 3D models, every stakeholder, from engineers to owners to machine operators, can intuitively understand what the result of a project will look like.

You can even adjust 3D models to show what the site will look at different stages of the project or offer several variations on a plan, all in the form of a realistic, easy-to-understand visual.

When You Need Comprehensive Information

While 2D models are useful for when you want a simple view of only specific types of measurements, 3D models are valuable because they can include a much wider array of project information. 3D modeling allows you to collect all of your information in one place so you can get a comprehensive overview of your project.

With 3D modeling, you can include basic site layout, grading, utility lines, landscaping and more all in one model. This capability allows you to see how different elements interact and see what a project will look like at various stages. You can also look at different layers of a model and explore it from different angles to get a more complete picture of a plan.

3D Modeling Allows for More Comprehensive Data

These features can help you to check that plans are accurate and feasible and ensure that you follow plans closely as you work. It’s also useful for costing and timeline estimating, as the increased volume and detail of information allows for more accurate estimating.

3D models can also help you to take more precise measurements because you can navigate around elements and view them from different angles. It’s easier to distinguish between various elements and ensure you measure them correctly in 3D than in 2D. Even 2D measurements, such as cross-sections, are easier to take when displayed in a 3D environment.

When You Want to Use Models for Machine Control

One of the most valuable uses of 3D models is machine control. Machine control involves the use of positioning sensors, such as GPS systems, sonic tracers, rotating lasers and total stations, to guide machines. These machine control systems use the information from 3D models to determine where exactly on a site a machine should be, the position a machine’s bucket or blade needs to be in and target grades. Sensors on the machinery communicate with the onboard computer, which is loaded with a 3D model of the project, to ensure the project is completed accurately.

In addition to increasing accuracy, the use of 3D model machine control enhances machine productivity and efficiency, reduces machine-related and raw material costs, eliminates the need for ongoing grade checking and increases worker efficiency. It automates significant portions of work and can take the place of traditional methods like the use of surveyor’s stakes.

When You Want to Conduct Virtual Inspections or Walkthroughs

Creating a 3D model of a project also allows you to conduct virtual inspections and walkthroughs. Having a 3D model of a site available enables you to conduct thorough inspections of various aspects of your site from multiple angles without having to physically be at the site. You can also conduct virtual walkthroughs in a similar fashion to show others your site or update them on the progress of a project.

When You Want Enhanced Communication Over Distances

3D models make communication easier, as they enable you to include more information in one document and present it in an easy-to-understand format. Everyone can have access to the same information and see it in a way that makes the information clear so everyone is on the same page. This capability helps ensures that the results of a project meet everyone’s expectations. You can communicate with various parties using 3D models even if they’re all in different locations.

If not every party involved in a project is using 3D models, you may have to convert information back and forth between 2D and 3D. When a model is converted to 2D, it won’t contain as much data, meaning some information may become lost in the process. Converting the model makes communication more complex and susceptible to error.

When You Want to Ensure Accuracy

3D models can help ensure accuracy in various ways. It can make communication clearer and easier. It collects all of the information in one place. When you use 3D models for machine control, it helps machine operators complete grading and other work more precisely.

ensure accuracy with 3d models

3D modeling can also help to reveal issues with plans before work on a project begins. Because a 3D model creates a realistic interpretation of what a completed project will look like, it’s easier to spot clashes or inconsistencies. You can look at a 3D model from various angles and check that the design is accurate and realistic. Because you can see more information in one model, you can also see where elements clash, such as electrical lines that a plan shows running through rock in the ground. With a 3D model, it’s easier to spot and correct a variety of potential issues.

How to Make the Right Choice for Your Models

So, how do you know whether a 2D or 3D model is right for your next project? You’ll need to consider certain aspects of the project, what technologies are available to you, what your partners are using and various other factors.

It’s important to keep in mind that, for many projects, using both 2D plans and 3D models may be useful. That way, you have both a simplified document and a more detailed model that you can reference as needed.

When deciding what type of model to use for a project, consider the following factors:

  • The complexity of your project: If your project is relatively simple, you may be able to just use 2D plans. Because 3D models can contain and communicate more information, the more complex your project, the more important it is to use a 3D model. While even simple projects could benefit from a 3D model, with more detailed projects, there is a greater need for 3D modeling.
  • The information you need: With 3D models, you can include more types of data. 2D models can only accommodate two dimensions, while 3D models can also account for depth. It’s also easier to include various other types of information in a 3D model, such as information about costs or utility lines. In general, the more information you have, the more useful 3D modeling will be to you.
  • How you plan to use the data: If you want to use your data for machine control, a comprehensive inspection or a virtual walkthrough, you’ll need to use 3D modeling. A 2D model cannot accommodate these more advanced uses.
  • The technology being used: Consider the technologies any partners on the project are using. If others are using 3D modeling, it may be beneficial for you to use it as well, as this will make communication and collaboration easier. Also, think about what technologies are readily available to you. For example, are your machines already wired to work with machine control based on 3D models?
  • Costs: Costs are always an important consideration for construction projects. 3D modeling may come with a higher upfront cost than 2D plans, especially if you need to invest in equipment before you can take full advantage of it. However, it’s important to consider the cost savings that using 3D modeling can provide over the long term due to increased efficiency and accuracy. Also, consider the costs of using outdated technology and the possibility that competing firms may be using more advanced technology.
  • Consult with an expert: It’s also helpful to consult with an expert in construction and modeling. They may be able to help you determine the right technologies to use for your project.

Work With a Data Modeling Expert

At Take-Off Professionals, our team of licensed engineers, surveyors and 3D modeling techs create, on average, 1,000 machine control models each year. We have over 20 years of experience building 3D models for machine control, site work and layout, as well as providing earthwork takeoffs. We provide detailed quotes and accurate turnaround times and can prepare your data any way you need it. Contact us today to discuss how we can help you win more bids and complete projects with increased efficiency and accuracy.

work with a 3d and 2d modeling expert

Types of Civil Surveying

Types of Civil Surveying

Civil surveying is essential for the success of many construction projects, from residential and commercial buildings to infrastructure. It gives project managers and engineers the geographical information they need to build a structure that will stand up reliably in the local terrain and helps them map out how their project should unfold.

Within civil surveying projects, 3D modeling using survey data is a vital technique. The Federal Highway Administration recently analyzed an interchange project in Milwaukee, Wisconsin, and found that the use of 3D modeling reduced operational costs by up to 30.5 percent, especially in the construction of general structures, drainage and bridges.

But what is civil surveying, exactly, and what different forms does it take for different projects? In this guide, we’ll discuss what surveying in civil engineering is, its purpose and how different types of new technology help accomplish civil surveying goals.

What Is Civil Surveying?

Civil surveying is an engineering operation that involves assessing and recording details about an area of land. These observations can then be used to help plan construction projects.

The main purpose of surveying in civil engineering is to determine the three-dimensional relationships between different locations. Knowing information like the distances and angles between points and lines helps engineers determine how to draw up plans for public buildings, homes, roads, bridges and a variety of other construction and infrastructure projects.

The points that engineers measure are often located on the surface of the earth, though they can also be located in space. Because intricate, precise spatial relationships and boundary lines are so integral to this process, civil surveying draws on aspects of different disciplines, from mathematics to geography to law.

Civil surveying also involves specific equipment and GPS data acquired from satellites. High-precision electromechanical and optical equipment is also a necessity for ensuring measurements are accurate.

So, what is the importance of surveying to civil engineers? Civil surveying is useful in a tremendous variety of different applications, including:

  • Creating topographical or marine navigational maps.
  • Preparing plots.
  • Planning for new construction projects.
  • Estimating projected paths of roads, railways, power lines and irrigation systems.
  • Assessing and recording the boundaries of different properties to determine land ownership.
  • Analyzing topography.
  • Assessing the position of existing structures like highways, canals, dams and bridges.
  • Planning and constructing mines.
  • Preparing for military operations and engagements.
  • Charting navigational routes.

History of Civil Surveying

The history of civil surveying goes back to ancient times. Egyptians used geometry to reestablish farm boundaries after dramatic flooding along the Nile River, and they used surveying techniques to design and construct the massive, geometrically precise pyramids at Giza, one of the wonders of the ancient world.

During Roman times, the role of civil surveying took on a prominent place in society, becoming an established profession. Land surveyors created the measurement systems they needed to evaluate and create a tax record of the lands they had conquered.

In the eighteenth century, European surveyors developed the technique of triangulation when they realized they could use different angle measurements taken from different places to pinpoint a precise location. And as the British colonized Australia and New Zealand, they used new tools such as measuring wheels, Gunter’s chains, Kater’s compasses and circumferentors, though they also resorted to measuring out paces by foot when necessary.

Gradually, tools like Gunter’s chain — which measures a precise 66 feet, or 1/80th of a mile — gave way to steel bands and invar tapes, and later to electromagnetic distance measurement (EMD) and global positioning satellite (GPS) equipment. Likewise, compasses gave way to theodolites — instruments that measured horizontal and vertical angles with a rotating telescope – which in turn made way for total stations that took measurements of angles and distance with a solo instrument.

construction surveying

Different Types of Civil Surveying

Although construction is the most common type, engineers need to survey a wide range of features, from mountains to oceans to rivers. Engineers use several different types of civil engineering surveys, including:

  • Construction surveying: Construction surveying is useful for assessing the arrangement of the buildings, roads, power lines, gas mains and other structures surrounding potential construction sites. Analyzing this information makes it easier to plan construction projects.
  • Deformation surveying: Deformation surveying helps to establish if a geographical or man-made feature, such as a road, foundation, coastline or river, is changing shape. In deformation surveying, engineers record the three-dimensional coordinates of specific points. After some time has elapsed, they record the coordinates again to see if they have changed. A comparison of the two data sets can reveal if deformation or movement has occurred.
  • Geological surveying: Geological surveying maps out features of the physical landscape, such as rivers, valleys, mountains and more. Satellite data is essential for geological surveying, and engineers frequently use satellite data or aerial photographs to help them in their work.
  • Hydrographic surveying: Hydrographic surveying is similar to geological surveying, but it maps out coastlines specifically. Accurate hydrographic surveying is crucial to the work of the Coast Guard and any marine rescue operations. It also helps create navigational maps for sailors and assists conservationists in managing coastal resources.
  • Topographic surveying: Topographic surveying analyzes the shape and physical features of a particular landscape. Engineers assess the height of different geographical coordinates and then draw contour lines to indicate areas of the same elevation. They can then use these findings to create topographical maps and to assess terrain for future building or infrastructure projects.

Technology Used in Civil Surveying

Since ancient times, engineers have developed a host of tools to help them survey all types of features. In civil surveying, different types of technology are available, like:

  • Computer-assisted drawing (CAD): Once engineers have gathered survey data, computer-assisted drawing helps turn that data into a useful visual representation, such as a map or three-dimensional model. CAD allows for a greater level of precision and detail than could not be achieved with manual sketching or drawing.
  • Global positioning satellite data: GPS data is crucial for civil surveying because it allows for the pinpointing of precise locations and coordinates. Where a visual assessment alone would be insufficient for determining whether a corner had shifted or a foundation had sunk, the pinpoint accuracy of GPS data allows engineers to know for sure.
  • Aerial photogrammetry: Drones are often useful for the aerial photography necessary in civil engineering. Once they have a number of aerial photographs of the landscape or site in question, engineers can use aerial photogrammetry to extract topographical data from the photos. Aerial photogrammetry combines multiple shots from different angles to create an accurate 3D model.
  • Point cloud modeling: To develop accurate 3D survey models, engineers also often create a point cloud or a set of three-dimensional data points. Surveyors use 3D laser-scanning technology to generate a data map of the area they wish to model. Once they have data that represents every surface they need, they can then bring the points together through point cloud modeling into an accurate and detailed 3D model.

Choose the Data-Prep Experts at TOPS for All Your Civil Surveying Needs

When you need 3D modeling to get a construction project or bid off the ground, Take-Off Professionals can help. All our engineers are full-time employees, never contractors, so you’ll always work with someone who is fully integrated into the company, experienced with our techniques and invested and in the success of your operation.

work with data preparation experts

We also stand apart from the competition because we don’t manufacture or sell hardware or software — we specialize only in takeoffs. That specialization has allowed us to develop an unparalleled wealth of technical expertise and vision in civil surveying. We can optimize our work for commercial sitesresidential sites, and road work and highway operations, so you’ll always get the customized surveying solution that works best for you.

Check out our compelling list of reasons you should work with us, and then contact us today to learn more.

Land Surveying With Drones

Land Surveying With Drones

Surveying is a profession that requires patience and accuracy. Companies across many industries need surveyors to evaluate large plots of land and provide them with detailed mapping and measurements. From construction crews to archaeologists, having an aerial view or 3D model of a worksite is essential to starting and finalizing their work. Without these images or models, workers can’t make informed plans about where to dig, what to fill or where to start building. But surveying in the traditional methods and creating precise mapping takes time.

Drones, otherwise known as unmanned aerial vehicles (UAVs), have been changing the way surveyors work. With their rise in popularity, manufacturers have created drones for a wide variety of purposes, including utility models for companies that need to inspect or collect aerial images of worksites. This guide to land surveying with drones will explain what UAV surveying is, how UAV surveying is being done, what they work well for and how accurate of an image they provide.

What Is Drone Mapping?

Drone mapping is the process of surveying an area of land with a UAV. An operator flies the drone over an area of land, taking hundreds of pictures as it moves. Then, with the help of computer software, they stitch and layer the images, creating a model of the site. This process is also how drone photogrammetry works, and the end result is an accurate 3D representation of the area.

Who Uses Drones for Land Surveying?

Many industries require surveyors to provide maps of areas of land. From establishing the general grade of an area to creating detailed maps of every square foot, drone surveying makes the job easier, faster and safer for surveyors. Among the many industries land mapping with drones, some of the most significant include:

  • Construction: There are many answers to how drones are used in construction. Companies need surveyors to start almost any project, but they especially require their help on large-scale builds. Drone imaging aids them in establishing plot boundaries, creating legally acceptable subdivisions and evaluating the suitability of the land before beginning any foundations. With the provided information, construction companies can make important preliminary decisions that ensure optimal safety and legality for the project.
  • Oil and gas: The installation of oil and gas pipelines requires a significant amount of planning. Drone surveys help these companies evaluate where pipelines can and can’t go, whether it’s due to proximity to natural resources and conservation sites, preexisting construction or infrastructure or privately owned property.
  • Infrastructure: When it comes to designing and constructing new roads and bridges, infrastructure companies need to know the details of the surrounding land. Drone imaging can help them examine areas and determine if they need reshaping or if the land is suitable for construction in the first place.
  • Archaeology: Before archaeologists conduct digs, they need to survey the area to decide whether or not it looks like a promising location. Using drones allows them to do so quickly and at minimal expense, saving them time and allowing them to pinpoint interesting areas.
  • Mining: Quarries and open mines can be dangerous areas for traditional surveyors, but mining companies often need a mapping of their worksites. UAVs provide an excellent method of capturing aerial images and creating computer models while keeping their surveyors as safe as possible.

Is Drone Surveying Accurate?

Before drones had an impact in the surveying field, creating accurate maps or 3D models of large plots of land would take anywhere from days to weeks. Now, UAVs allow surveyors to create models of comparable precision within a much shorter period. But accuracy in the surveying industry doesn’t have a single definition, and many different models of drones are available.

To understand how well drones perform, you have to consider several factors in regard to accuracy. There are many potential influences as to how well a drone can photograph an area. You also have to consider what you’re using the map or model for and what your standard of accuracy is for the given project.

Survey Accuracy vs. Pixel Size

One of the most essential details to consider is the drone’s operating pixel size. The spatial resolution of the UAV, also called the ground sampling distance (GSD) in technical terms, is the measurement of the space on the ground between two side by side pixel centers in the image. A drone’s GSD depends solely on the specs of its camera, including its resolution and focal length. Different camera models will provide different resolution qualities, resulting in varied GSDs.

When it comes down to measuring precision based on pixel size, your judgment should be based on positional accuracy. Essentially, this means the degree to which the model created by photogrammetry corresponds with the real world it represents. Still, there are two ways of looking at the accuracy of your mapping — relatively and absolutely.

Relative Accuracy

In photogrammetry, relative accuracy refers to the objects within a reconstruction and how they are positioned in association with one another. This applies to any orthophoto map, digital surface model or 3D mapping.

relative accuracy in land surveying

Relative accuracy is an acceptable form of measurement for most cases where the surveyor is dealing with a smaller area or simple uses. It can be helpful for providing general volumes, heights and distances, as well as recording vegetation. However, it’s not the most accurate mapping you can obtain.

Absolute Accuracy

Whereas relative accuracy is more general and based on its own proportions, absolute accuracy is based on a geodetic coordinate system. It takes the measurements between objects within the model and compares them to their real-world positioning relative to Earth.

Having a geodetic reference system to apply allows the surveyor or digital model creator to complete more complex functions. For example, they can create professional documentation of surveying, use the recorded geographic coordinates and combine layers for more comprehensive data sets.

Absolute orientation uses ground control points (GCPs), which allow the surveyor to create a coordinate system through the known coordinates of visual landmarks within the image. But to obtain an absolutely accurate mapping of an area with drone imaging, you have to begin by measuring GCPs through professional GPS equipment.

What Influences Accuracy?

Many elements can affect the accuracy of your drone mapping, especially if you’re dealing with the precision of an absolute accuracy model.

First, there are the apparent influences, such as the drone’s ability. Higher quality drones will perform better, from the stabilization mechanics to the camera. Beyond hardware, there are also plenty of outside factors, such as the terrain itself. Particularly rough or uneven terrain can throw off measurements and make it difficult to create a fully accurate mapping. Weather also significantly comes into play, as heavy winds and precipitation can affect the flight speed and stabilization of your drone, especially at high altitudes.

One of the biggest factors that can impact the photogrammetry process is your GCP measurements. However you identify these crucial points, your model can only be as accurate as your starting markers. To create the most exact mapping possible, make sure you measure the GCPs with a smaller unit than the pixel size of your drone imaging. For example, if your drone camera provides an image with 1-centimeter pixels, you should measure the points within a single centimeter of accuracy.

Absolute accuracy essentially builds on relative accuracy, meaning you have to have a proper relative model within the absolute one. Therefore, the accuracy of the absolute model depends on how precisely you measure your foundational relative model. Drone mapping involves taking potentially hundreds of photos with a non-metric camera and stitching them together to create a single image. More often than not, this means not every pixel will be sitting in the perfect position in your relative mapping.

How Accurate Can Drone Surveys Get?

While photogrammetry provides surveyors with a far more accurate means of creating a digital model than other methods, no imaging can be perfectly precise. The ultimate goal is to create a model with the smallest degree of difference possible.

For relative accuracy, it’s expected that maps will have a horizontal and vertical error margin of one to three times the size of the pixels. For absolute accuracy, the margin should be a bit smaller, typically measuring at about one to two ground sample distances (GSDs) horizontally and one to three GSDs vertically. Even if your mapping lies outside these parameters, it may not be an issue, as particularly rough terrain can throw off measurements more than flat or level surfaces.

create accurate models with drones

Drones are exceptionally capable of staying within these margins of error, as long as a trained and experienced surveyor is operating the machine. You can improve your accuracy by way of additional measurements between landmarks, using GPS reference points besides GCPs, improving your drone’s hardware, ensuring you’re working in favorable weather conditions and carefully stitching together the base images.

Where Can I Use Drones for Surveying?

As the use of UAVs has been becoming more prevalent in industrial and recreational applications, the regulations have also increased. Before you can begin using industrial-grade drones to your advantage, you need to obtain legal permission to use them. However, it isn’t a particularly challenging process.

The Federal Aviation Administration (FAA) has control over all methods of aviation, including UAVs. To use drones in a commercial capacity, the official operator needs a Part 107 remote operator’s license. Essentially, it ensures you are knowledgeable about proper use and following regulations. To obtain the FAA license and maintain its validity, you have to:

  • Take and pass a test of your aeronautical knowledge at an official FAA testing center.
  • If you pass, acquire your small rating Remote Pilot Certification.
  • Register your drone with the FAA and renew the registration every three years.
  • Retake and pass the aeronautical knowledge test every 24 months to retain your license.
  • Follow all FAA regulations, which include but are not limited to drone and control system inspections before operation as well as reporting any accidents that result in injury or significant property damage to the FAA within 10 days of the event.

Once you are a licensed operator, you can use your drones to inspect any areas you are permitted to survey by the landowners. It’s up to you to gain permission to access areas marked private property or land plots owned by companies.

What Can Drones Be Used to Survey?

The benefits of drone surveying cross over many different industries and provide an accurate method of inspecting and evaluating small or large areas of land. These areas may be bare and ready for developments, they may have thick vegetation or they may even already have developed construction. Since there are many purposes for drone surveying, their usefulness applies to many different areas. From flatlands to deep pits, drone imaging provides an excellent way to safely and precisely create models of an area.

what can drones be used to survey

When it comes to how drones are used in surveying, there are many answers. Some of the most significant uses include:

Land Development Sites

As technology has improved over the years, land departments have become more inclined to use drones to provide comprehensive land recordings of real estate or property. Drones suitable for land surveying can take orthomosaics, also called orthophotos. Orthomaosaics are groups of multiple aerial phots of an area edited together to form a single image through photogrammetry.

Land departments use orthophotos for things like developing single object mapping layers and updating land cover on preexisting models. They use it even more frequently to create topographic maps for new developments, such as various forms of building construction or designing noise barriers.

Urban Land Management Sites

Drones are exceptionally useful for surveying many different types of land sites, and they make management far easier for the responsible parties. They have nearly a limitless amount of potential applications and services, such as using the digital surface models produced by the drones to create virtual models of plots. They’re particularly useful to urban land management.

Those working within the industry can use drone surveying to import images into computer-aided design (CAD) software to create accurate virtual models of developments. With orthomosaics, which are essentially stitched and overlapping images, management teams can create defined boundaries with the benefit of a precise, aerial view. They can even use the models for more complex functions, such as simulating where water would flow and settle in the event of a major flood and creating a plan to redirect it.

Construction Sites and Earthworks

When it comes to planning for construction, surveyors and the various landscapers and builders are responsible for a lot of preparation. They have to calculate cut and fill projects, complete surveys for pre-construction and as-built properties and oversee the details of the site from preparation forward.

Drone surveying provides these workers with a revolutionary method of imaging and plotting construction sites. It allows them to create an accurate model and plan without continually needing to access the physical job sites, saving time and money.

Mines and Quarries

Surveyors don’t always have the benefit of a safe site. Mines and quarries can pose a safety risk, especially for those attempting to inspect a site at ground level. Geologists and surveyors benefit from using drones as an aerial method of inspection, enabling them to collect accurate data and spatial measurements while lowering the occupational hazards. They also help to boost productivity in quarries and pits, as drone imaging allows workers to make improvements to planning and inventory management.

Archaeological Sites

Beyond companies looking to build and remodel areas of land, there are still many uses for drone surveying. For one, they’re particularly useful in the field of archaeology. With drones, archaeologists can create 3D surface models and high-resolution mapping of potential excavation sites. Doing so allows them to inspect and assess the worthiness of large areas of land much faster and with more accuracy than any other method. It’s efficient, cost-effective and saves their teams a lot of time and energy.

Get Accurate Models From TOPS

Whatever industry you’re a part of, Take-Off Professionals (TOPS) has everything you need to create accurate 3D surface models of your worksite. Our team of professionally trained engineers and surveyors have years of collective experience using drones and accurate photogrammetry techniques to assist our clients. TOPS can help you tackle any challenging project, and with our services, you can start and finish faster and with more confidence.

partner with a data prep expert

Partner with TOPS today — contact us for more information or register your company to get started.

Future of Surveying Technology

Future of Surveying Technology

From the ancient wonders of the world to the modern buildings we inhabit today, surveying technology has been helping us measure for thousands of years. We’ve come a long way from the rope stretchers of ancient Egypt, but land surveying technology is still evolving. Like every industry, the future of land surveying is set to change in the coming years. Between an increase in drone usage, improvements in mobile 3D mapping and changes in data management, surveying has many developments ahead of it. The trends have implications for the industry that can improve data collection, change data storage approaches and offer more accessible and flexible information gathering.

Today we’ll be going over what the future of land surveying technology looks like and what some of the top land surveying trends are shaping up to be.

The Use of UAVs

Unmanned aerial vehicles (UAVs) have become more and more accessible and affordable, making them great additions to a surveyor’s arsenal. Before their widespread availability, they were often thought to be cost-prohibitive for many applications and were reserved for military use. Now, they offer several advantages over both terrestrial surveying teams and manned aircraft. Drones can:

  • Cover large surface areas in a short amount of time
  • Cross difficult terrain
  • Take detailed images of hard-to-reach landscapes
  • Accomplish land surveys, photogrammetry, 3D mapping, topographic surveying and more

Traditional methods often couldn’t complete these tasks, whether due to complex terrain or the sheer amount of time it would take with land-based approaches. Surveyors can now get their aerial data quickly and accurately with modern drones. UAVs also make the job safer, so human operators don’t need to fly over or enter hazardous environments to take measurements. Drones are becoming standard, less of a “bonus” and more of a necessary component of landscape businesses. Using them may soon become an industry standard.

UAV being used for surveying

Drones are also often used for cadastre, opening up a significant area of use. In addition, they can provide data that integrates with computer-aided design (CAD) software to build models for land development and management. Another benefit of drone usage is that it can provide a variety of photos for recording land data and structures.

Some other forms of data that you can collect from drones include:

  • 2D Orthomosaic maps: Stitch together photos from a drone to create a top-down aerial view.
  • 3D Orthomosaic maps: Stitch together images to compile a 3D birds-eye view of a space.
  • 3D models: Create detailed models from powerful mapping software.
  • Thermal maps: Record and identify abnormal heat signatures in an area.
  • LiDAR point clouds: We’ll talk more about LiDAR in the next section, but drones can help you create a high-density point cloud for use with this system.
  • Multispectral maps: Data outside the visible light spectrum can offer a variety of uses, including missile detection and satellite imaging.
  • Building information modeling (BIM): Combine high-resolution 3D programmatic or laser models with pre-made BIM objects. This information can help to identify variations and respond accordingly.

When it comes to achieving the greatest possible accuracy, drones can use additional tools, like real-time kinematics (RTK) and post-processing kinematic (PPK) positioning. Both are positioning techniques that can improve the precision of the data using information from satellite-based systems.

Mobile 3D Mapping

Mobile mapping systems can provide extremely detailed images in a short time. They are flexible and allow you to create 3D models from a wide variety of environments. Indoor, outdoor and underground areas can all be extensively detailed with mapping technology.

It is fairly straightforward to collect geospatial data and use software solutions for fast and simple mapping. Surveyors can create digital replicas without cumbersome equipment or the need to wait hours to see the results. Versatile equipment options, handheld devices and aerial recording make mobile 3D mapping a viable and effective approach for many land surveyors. Many of the sites a surveyor visits can be dangerous or difficult to access. While they could spend valuable time and money trying to get into the area on foot and use traditional terrestrial tools, a more efficient option would be to use a UAV. Plus, this method keeps them out of any treacherous terrain. Similarly, if a surveyor needs to make a model of an extensive area, they can attach their recording devices to a vehicle and move through the site this way, offering a less physically taxing job and a faster result. These methods require very little training and are easy for new users to operate.

Mobile 3D mapping is available without the use of GPS and in durable, splash-proof products, offering additional flexibility. This kind of product can help you map out hard-to-reach places, whether they are dark, dank or dangerous, through several different methods. Tools are often made to be light and portable for ease of use.

One of the most notable benefits of this kind of mapping includes real-time, instant results. You can transform your data into 3D visuals quickly, reducing the time it takes to see results. 3D-mapping software also tends to offer robust organizational features, such as bundling data into projects and managing single uploads automatically. This organization can extend to mobile devices, including apps and third-party plugins. Some even provide features such as automated measurements, asset inventory workflows, face blurring and more to offer more of an all-in-one approach.

Data Accessibility

Another growing piece of technology is LiDAR, a form of 3D laser scanning. LiDAR stands for Light Detection and Ranging and uses a pulsed laser in ultraviolet, visible or near-infrared light to measure variable distances to the ground or nearby objects. The machine is composed of a laser, a special GPS receiver and a scanner, and they usually utilize airplanes and helicopters to gather their data across large areas. This remote sensing method collects information from the light pulses and other data collected from the aerial system to create detailed 3D models or gather survey information about the physical characteristics of the Earth.

LIDAR being used for measuring

There are several different types of LiDAR, including:

  • Terrestrial: This type of LiDAR maps the Earth’s surface through topographical measurements that are mounted on the ground. Surveyors can map 3D-point clouds from the scanner with digital images to quickly make realistic 3D models. It can bypass the cumbersome tasks of measuring each item, like power lines, bridges, trees and more that may be in an area.
  • Bathymetric: Bathymetric LiDAR measures elevations of riverbeds and seafloors with the help of a green light that penetrates water and its reflection back to a sensor. The measurements are typically taken from the air.
  • Airborne: A laser scanner can be attached to an aircraft and used to create a 3D-point cloud model of a landscape. It is detailed and accurate, helping to create digital elevation models (DEM) and digital surface models (DSM).

This system provides a new level of precision and flexibility to the measurement of both organic and manmade structures. It may also pave the way for the automation of vehicles and assisting in lunar-landing vehicles. LiDAR is growing in use in a wide range of applications:

  • Agriculture: Topographical data from LiDAR can help identify patterns of sun exposure, insect behavior and features in the landscape to improve farming tactics.
  • Archaeology: Archaeologists use LiDAR technology to help plan field campaigns, map features under tree cover and create DEMs of archaeological sites for more detailed images. For instance, in 2013, it was used to rediscover the city of Mahendraparvata in the Cambodian mountains.
  • Atmosphere: LiDAR is used in meteorological applications to provide information on surface pressure, greenhouse gas emissions, fires and photosynthesis. It can measure backscatter from the atmosphere and reflections that scatter off a hard surface.
  • Physics and astronomy: LiDAR can help measure distances and the position of the moon and create topographic information about other planets.
  • Wind farms: LiDAR can measure wind speeds and turbulence to help optimize the performance of wind farms.

One of the major benefits of LiDAR is that it offers real-time point clouds. Not all systems have this option, but many do. This feature can provide significant advances in the way of speed and accessibility, making projects more flexible and efficient.

As LiDAR systems become less expensive and more accessible, they are likely to be more common in survey projects.

Outside of LiDAR, general data accessibility is likely to improve, as more advanced tools become more affordable. Products that were previously reserved for only the most prestigious of tasks, like those in the military, will become more commonplace and may even become industry standards.

Cloud Storage of Data

As scanning technologies have become more complicated and advanced, they have started to create more data. All of that data takes up valuable space and can quickly become a burden on the IT capabilities of land surveying organizations. Many of them don’t have the storage infrastructure to support such a growing amount of information in a physical, on-site data center. To remedy this, many companies are turning to cloud storage, in which data is kept off-site, in a secure location and managed by a third-party company. Often, these companies offer high levels of security with dedicated experts working around the clock to protect their clients’ data. Most importantly, it takes the burden of finding space for the data away from the survey companies. They can spend less time worrying about the security of their information and more time working on projects or investing in better equipment.

These survey organizations have to store data for thousands of projects, and they can repeatedly outgrow their capacity as they accumulate more projects and business. Cloud storage is scalable and allows land survey companies to leave the issue of storage capacity to their servicer. Storage infrastructure can be costly and time-consuming, so many organizations are aiming to offset these problems and let someone else manage their information. Similarly, processing power can also be scalable. Some point-cloud software uses significant amounts of processing power from an off-site cloud center to deliver high-demand results to the user. The option to beef up power when needed is often appealing to surveying companies.

Another reason that many companies are moving to cloud-based storage is for the ability to share and access data more easily. Cloud storage eliminates the need to send files, which is essentially copying and redownloading them, often resulting in duplicates or creating unnecessary data. As well as taking up extra space, this can lead to misinformation or outdated files. With cloud storage, users can instead access the same data, and they can do so from a variety of devices wherever they have a connection. In-field access is an excellent tool for surveyors, offering them the ability to upload scans and view data as needed while on-site.

cloud based storage helps with accessing data

Here are a few more reasons companies are moving to the cloud:

  • Manageable costs: Startup costs for extensive data storage can be high, but many cloud data servicers run off of subscription models. This approach can make the service more affordable and predictable for land surveying companies, but it would also be a monthly cost rather than a capital investment. Organizations will have to decide if that approach is right for them.
  • Reduced maintenance: Surveying companies don’t have to worry about updating or installing local software and may save on IT costs and time. Plus, they receive the help of dedicated digital storage professionals to keep an eye on things.
  • High power: Some organizations need to run robust programs to read and analyze their data, which may take ages on a local computer. Cloud-based software can offer higher-powered programs that may be able to get the job done quicker.
  • Automated scans: Some programs can automatically start registering scans into a composite point cloud as they are uploaded. This approach can speed up the process and even help surveyors access completed point cloud data from the worksite.
  • Collaboration: Many surveyors have to work with a variety of partners, including contractors, engineers and other stakeholders. Cloud services make sharing data with third parties much more straightforward than before. Surveyors, management, engineers, clients and more can share information quickly and with controlled permissions, improving collaboration between parties. Surveyors can ensure that only those who need access can view the data, as well.

Though cloud-based storage is a powerful tool, it can change the way organizations operate. For those using massive amounts of data, costs can add up. Surveying companies must crunch the numbers and analyze their unique needs to find out if cloud data is right for them.

Work With Data Modeling Experts

For your data modeling needs, Take-Off Professionals has been creating accurate 3D models for over 20 years. Whether you are a contractor or surveyor, we can provide fast and accurate quotes for 3D machine control models.

When you work with us, you work with industry experts. Our team of licensed engineers, surveyors and 3D technicians ensures that we stay up to date on the latest technology and industry trends in land surveying. Whether its the ease of use and versatility of UAVs, the flexibility of mobile mapping or the changes in data storage, you can be confident that our staff is up to date on these topics and whatever comes next for the future of land surveying and surveying technology.

Learn more about our data preparation, quantity takeoff, and GPS machine control modeling services!

work with data prep experts