New technologies are always disrupting the construction and civil engineering industries. Point cloud modeling has existed for a while, but it’s becoming a major tool for contractors and engineers who seek more ease and efficiency when conducting land surveys. It accomplishes the same work with fewer resources spent — which is what every person wants from their business endeavors. But what exactly is a point cloud, and how does it help with surveying work sites?
If you want to learn how to use a point cloud for 3D models, this article can show you how it works — plus what you can gain from it.
What Is a Point Cloud?
A point cloud is a collection of many small data points. These points exist within three dimensions, with each one having X, Y and Z coordinates. Each point represents a portion of a surface within a certain area, such as an engineering work site. You can think of these points similarly to pixels within a picture. Together, they create an identifiable 3D structure. And the denser your point cloud is, the more details and terrain properties you’ll see within your image.
Creating and utilizing a point cloud puts a world of data within your reach, but you must know what to do with it after you generate it. This question can pose a problem for some surveyors — and others may not know how to create a point cloud to begin with. However, both of these problems have easy solutions. When you outline the goals you want to achieve from using a point cloud, you’ll know how to obtain your data and get the most value from it.
You can create point clouds by using two primary methods — photogrammetry and Light Detection and Ranging (LIDAR), which we will discuss in more detail below.
How Is a Point Cloud Created?
How do you create a point cloud when it involves so much detail and so many small points? The answer is typically a laser scanner. Site surveyors can create 3D models from point clouds by using LIDAR lasers. With the laser, you scan a chosen environment — such as a construction site — and the scanner records data points from the surfaces within it.
Once you have the complete point cloud, you can import it into a point cloud modeling software solution. At this stage, you can modify the data points for better accuracy. To see the point cloud in a 3D format that resembles your terrain, you’ll need to export the data from your modeling platform and upload it into a computer-aided design (CAD) or building information modeling (BIM) system.
Using Photogrammetry for Point Cloud Surveying
Photogrammetry is a common method for creating point clouds. With this technique, a drone takes numerous pictures of a construction or civil engineering site. Because the drone uses a camera, you’ll likely need to adjust its settings for the site’s environmental conditions to get the best results. Various angles are required to capture a full view of the landscape. Once all the images are captured, you can use a processing platform to overlap the photos.
By stitching the images together, you can develop a point cloud, create a 3D mesh and produce a complete 3D model within a CAD or BIM program. The process of filling in the gaps between the data points and creating a mesh is known as surface reconstruction. That’s why it’s essential to get as many data points and images as possible — you’ll have fewer spaces to fill in or reconstruct.
In contrast to photogrammetry, remote sensing — which is what LIDAR is categorized as — uses aerial vehicles to study a work site and create data points from it in real time.
What Is a LIDAR Point Cloud?
With the help of drone technology, you can use LIDAR to scan an area and record its data points to produce a point cloud. LIDAR uses infrared light laser pulses to measure distances. When these pulses reflect back to the sensor, it measures how long it took for the light to return. These laser scanners can emit up to 100,000 pulses per second, which gives an incredibly detailed view of the area being mapped.
Once you’ve created your LIDAR point cloud, it goes through a similar process of being transformed into a mesh and developed into a 3D model. Mounting LIDAR hardware onto a drone allows you to use 3D laser scanning to map any area you choose. Attaching the hardware correctly is essential — incorrect setup can impact the drone’s balance, which affects your data’s accuracy.
LIDAR and photogrammetry produce similar levels of accuracy. When choosing which one to use, it’s better to consider factors like how long it takes to set up the equipment and which method will be easier for you to work with.
How Is a Point Cloud Used in Site Models?
What is a point cloud in surveying? Land surveyors use point cloud modeling to create expansive representations of landforms where it would otherwise require tremendous time and effort. Even if your project isn’t huge, using LIDAR drones to collect data increases your efficiency and overall work experience.
Civil engineering sites can consist of roads, subways systems, bridges, buildings and more, which can have complex structures. Surveying these locations manually can stretch out a project’s duration and require a bigger budget, but technological advancements like point cloud modeling streamline the process. In general, new technology has significantly impacted civil engineering within the last few years. Additive manufacturing, smart tech and artificial intelligence are just a few examples.
Drone technology and point cloud modeling could also become essential elements of the connected job site. Tasks like geolocation, transferring as-built information and remotely monitoring work sites can all benefit from these two technologies. In turn, companies can improve employee productivity and safety and reduce their insurance and liability costs.
Point Clouds in Earthworks
Point cloud modeling techniques use drones, which have become increasingly popular for earthworks and construction projects due to their flexibility and efficiency. They can fill multiple roles within the building process — from the beginning to the end of any project. Mining, surveying and agriculture are among the many industries that have adopted drone technology for process optimization.
Here are a few ways that drones have shaped modern earthworks jobs so far:
- Improved progress monitoring: Companies that commission earthworks projects don’t always have the time or resources to send people out to their sites to conduct regular checks. Drones enable them to inspect the progress by taking photos of the site and turning them into an orthomosaic. From there, they can use the orthomosaic to create a digital elevation model (DEM) and compare these daily shots to their final project plans.
- Better worker safety: Manual surveying may require workers to walk up and down steep slopes or through rough terrain, which can prove dangerous if someone falls. If you put a drone in the field instead, you can capture data from afar without the injury risk.
- Quicker cut-and-fill: Some companies use topographic surveys to do cut-and-fill comparisons, which can take days to perform on a large or complex work site. Processing the data adds more time to the schedule — but drones can accomplish data collection at faster speeds. Processing, importing and exporting this information using intuitive software becomes simpler.
Point Clouds Used for 3D Models
Constructing a 3D model can change in complexity depending on the building or landscape type and its features. Renovations or retrofits that must be done while the area is still in use add another layer of intricacy, but they are not impossible to do with the right tools. Laser scanners and high-tech modeling software solutions ensure that every possible object is identified and distinguished from the next.
For landscapes with complicated or richly vegetated terrain, it may be necessary to send a surveyor out to supplement any spots the scanner might miss. When you have your data points and begin the conversion from point cloud to 3D model, you’ll likely have more than one scan to work from. Similar to photogrammetry, you’ll need different angles of the same site to get the full picture.
Rendering the data into a 3D mesh organizes the points and sets a foundation that you can use to build a model. Exporting the point cloud creates a file that can be imported into a CAD or BIM system. What are the common point cloud formats? Depending on the software you use, you might see file formats such as:
- PTS: PTS is an open format for 3D point cloud data. Because open formats are maintained by standards organizations, anyone can use them.
- XYZ: XYZ is an archetypal American Standard Code for Information Interchange (ASCII) format. It’s compatible with many programs, but it has no unit standardizations, which can make data transfer more difficult.
- PTX: This is another common format for storing point cloud data, usually from LIDAR scanners. It can only be used on organized clouds — no unordered ones. It’s also an ASCII format.
- E57: This file format is vendor-neutral and compact. It can store point clouds and metadata from 3D imaging systems — like laser scanners. It’s also specified by ASTM International, with documentation in the ASTM E2807 standard. Additionally, it can store properties connected to 3D point cloud data, such as intensity and color.
- LAS: This open format is designed for data obtained from LIDAR scanning, though it can also accommodate other point cloud data records. It combines Global Positioning System (GPS) data, laser pulse range information and inertial measurement units (IMU) to create data that fits on the X, Y and Z axes.
- PLY: Known as the Polygon File Format, this type stores data from 3D scanners. It accommodates properties such as color, texture and transparency. It can contain data from both the point cloud and the 3D mesh.
Whichever file format you decide on, make sure your modeling software can convert your point cloud into one that’s compatible with your chosen CAD or BIM solution.
The Benefits of Point Cloud Modeling
Point clouds aren’t the only way to create 3D models, but they are incredibly beneficial for numerous reasons. Construction managers and civil engineers use 3D models for better machine control, improved accountability with project progress and true-to-life site layouts. Some of the perks of modeling include:
Uploading your point cloud into a photogrammetry platform lets you organize the data without the hassle of triangulating every point on X, Y and Z manually. The software does the work for you, which saves you hours of time you would have otherwise spent manipulating data. With these hours shortened, you can pull together the project details more quickly and begin your work sooner — which also means faster completion time.
Data collection is also faster because of the large number of points that can be recorded at once. A drone can sweep an expansive area in much less time than it would take for a surveying team to do the same.
Laser scanning and photogrammetry give quick and accurate results, transforming a living landscape into a detailed 3D model. Ground-based LIDAR can yield results that are accurate within a millimeter scale, while drone-based LIDAR is accurate from 1 to 30 centimeters. Its lasers can penetrate through dense vegetation for a more comprehensive site view.
Additionally, LIDAR often incorporates other features like GPS to ensure each data point comes with accurate information. Photogrammetry, too, uses Real Time Kinetic (RTK) geo-tags to ensure accuracy in recording the landscape’s form.
Because of the greater precision involved in site mapping with point clouds, you can plan a more effective budget for your projects. You can avoid going over your financial limit, and you’ll have fewer chances of running into any costly mistakes or unexpected expenses. Laser scanning also eliminates the need for manual surveying, which reduces the cost of hiring additional labor.
You’ll save money with these decreased or eliminated expenses, but you’ll also earn more on your projects. Your increased accuracy levels can lead more clients to trust you with completing their assignments, which boosts your reputation and encourages more companies to do business with you.
Work With a Point Cloud Modeling Expert
If you’re ready to incorporate point cloud modeling into your next engineering project, work with the experts at Take-off Professionals. We perform point cloud services and mesh conversions to help you process your data. Whether you’re working with a progress takeoff or an as-built, we can work with your information to provide the personalized results you need.
Working with a data modeling expert can help you save more money on your projects and finish tasks more efficiently. Conversion and processing require expertise and a fine-tuned eye for detail, which can lead to time-consuming mistakes if done on your own. By enlisting the services of our trained technicians, engineers and surveyors, you’ll receive results that have been refined by over 20 years of operation.
Fill out our form to learn more about how we can help you with your next job, or call us today at 623-776-9546. We do projects big and small, whether your point cloud consists of one construction site or acres of land.
From our previous post, “3D Data: More Than Machine Control
For many years, our business has been centered on the production of 3D data for machine control. This is the low hanging fruit of a civil site. High dollar paving, building pads, and retentions are easier to do and higher quality with machine control. Fast forward to current times.
Many civil sites are being completed with machine control. The use of machine control on the job site has become a reality, to the point that contractors have started to look beyond their current use and possibilities. As many of you know, I have long been a proponent of leveraging data for a job site. I have worked with many of our clients on how to better use the data they have in their hands and drastically improve production and profits.
I will go over several ideas that are good next steps for users of 3D site data. They are in no particular order of profitability. Any site may or may not be able to use these processes. Not to worry, I will back up the explanations with a video to better explain these ideas.
2D and 3D Points
Considered the domain of survey, a point has specific and relative information. I’ll use points for laying out a curb arc as an example. 3D points for the PC and PT of a curb arc give us the location and elevations of that curb run. We know the slope between the points and paving elevation is an easy calculation. Next, we add the arc center as a 2D point. Now there is a pivot to swing an arc for form or string line layout. Increasing the power of points, we offset the curb line to allow the field to set string line for a curb machine.
Using earth moving equipment to get the dirt right is a huge time saver. We also advocate the use of positioning technology for more than grading.
It started with light pole bases and quickly escalated from there. We now regularly provide data as 2D or 3D points for the following.
- SES pads. The job has been checked so we are good with drainage and elevations on the site. The electrical service slab is easy to calculate from available regulations.
- Common area in-ground power. Many plaza shopping centers have electrical connections for decorations and kiosks. Knowing the 3D location of the connections allows electricians to easily set them right the first time.
- Common area hardscape. Everything from playground equipment to benches, these additions need some type of base and connection. It is best to know what can be accomplished while access is easy and save re-digging to set later.
We have been providing utility layout for years. We show points 10 feet apart on the flowline for pipe with horizontal offsets if needed. Structures are marked as well. The advent of successful machine control for excavators has allowed us to provide a trench network so the operator can dig trenches correctly the first time.
Other utility details that can benefit from information provided in the data are:
- FES’s, wing walls and valley gutters. These concrete structures are better done in rough grade, but many contractors wait until near the end of construction and field fit. With a correctly prepared model there is enough confidence to build these when it’s convenient to the crew.
- Water lines are usually specified as a minimum depth below finish grade. We build the line in the data so crews can place it at any time and not make a mess of the just completed grading with required wheel trenching.
- Subdivisions have utility connections for each lot which we handle one of two ways.
- We can layout all the laterals and they are placed according to plan. When it’s time to make the connection, the rover is used to find the location of the pipe.
- When the utilities are not well defined or connections have to move, as-built shots are taken and we update the model for easy use in the future.
Taking shots along the way provide an ongoing record of what is being done. This helps to establish production rates as well as the basis for future submittal drawings. Here is one way to bring this into your workflow.
- I call this the “daily topo walk around.” While reviewing the work being done on a site, the superintendent has a rover and takes ground topo shots as well as items being put in the ground. In a perfect world, points would be coded but that is not critical.
- We often are asked to convert the walk around topos into as-builts or progress takeoffs. With the model on the screen overlaid to the topo points, we can usually figure out what the shots represent.
- Utilities are the biggest winner with as-built points. Before covering, if the top of pipe is measured, those are later converted to as-built drawings we put together for closing submittals. Many contractors have an issue with this, and we get it. It’s one thing to get the points but now the office needs to do full blown CAD drafting and plotting.
I will help to tie these ideas together in a video linked HERE. Please don’t hesitate to ask any questions you may have regarding these or other issues.
Update May 2020
All the things I discussed above pale in comparison to the big picture of data we strive for. All these elements are time savers and money makers, but they lead to the overarching point that data must be moved efficiently and used by everyone to be successful.
Let me follow some enhanced data through the process so you can see what needs to happen. In this example, I will work with the installation of a deceleration lane and entry to a commercial site.
- Plans are reviewed and data built to existing grades shown on the plans.
- Model works well with the information we have.
- I note the entry and ask the field to get measurements of the paving at the sawcut line.
- Site is set up and work starts.
- When appropriate, the field shoots paving elevations for the entry.
- The field notices the elevations are not matching with what they have on their model. The road is higher than what the model says it is supposed to be.
- Shots are sent to the office.
- I take the shots from the field and compare to the plan version of the existing conditions.
- I make the adjustments to the surface and entry elevations to line up with what is there. I do not want to design the entry, but I want to present a solution to the engineer if possible. Never ask a question you do not know the answer to.
- Information is sent to the engineer for collaboration.
- Engineer approves the changes. Always make sure you get this in writing such as email. Phone approvals will come back to bite you, don’t ask how I know.
- Model is updated and sent to the field.
As I have outlined here, the depth of 3D data is realized only when it is shared and leveraged by all parties. Share the information with engineers and surveyors to improve the quality and speed of the project. Everybody wins when you give out good data.
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.
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.
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 623-776-9546.
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?
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.
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.
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:
- 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.
- 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.
- 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
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.
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 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.
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 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.
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.
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.
At one time the only way to lay something out on a jobsite was to locate a point in 3-dimensions. With the advent of having real time/location elevations from a surface model, points have become less frequent on the jobsite.
There are three major uses for points on a job: layout, surface creation, and collection. I will cover these and their use in surface-based production.
There is nothing more precise than staking out a 3D point. Accuracy settings can be adjusted depending on the type of work being done. This screen capture shows the distance to the point I want to stake. When the point is eventually located, I will also have a record of the distance from the point for future reference. This is all related to what a surveyor does, the carryover to surface based layout may seem extreme.
This accuracy is best used by surveyors and is a bit fussy for grading in general, so why would we use that detail? I always enforce the seperation of field layout and actual staking done by a surveyor. Our layout of a point is only a snapshot of the surface and surrounding influences of other 3D data. This myopic focus will tend to take away the big picture view that is necessary for site work. Sometimes you just need to nail a spot and point layout gets you there. Here are some instances where spot layout is beneficial.
- Confirm a building corner for sidewalk offset.
- Bases for hardscape items and playground equipment.
- For curb layout we will often provide 3-foot top back of curb offsets for layout as well as pc’s pt’s and radius points for curves.
- Street and road details. Staking station and offset is quick with points.
- Lightpoles and electrical stub-outs are easy as points. Electricians will not have the technology to make sure you won’t need to dig up the asphalt due to misplaced electrical.
- Fire hydrants, bends and tees. This gets into as-builts which we will cover later.
- We do a lot of 3D point layout for storm and sanitary on projects. Flow line excavation and locating is much easier with points.
- Parking lot striping has been laid out with points with good results.
The list can get longer as users become comfortable with equipment and perform basic tasks quickly. If you want to do more, we have a list of things to do with point layout that can keep users as busy as they want to be.
Points in Surface Preparation
It’s obvious that points are going to end up being used in building a surface. What I want to cover here is what happens when you use a point that was not obvious. We get so wrapped up in what we use for a surface, take all the engineering data and build. I have seen users try all sorts of fixes to lines and contours when a simple point would make it all better.
Let’s first talk about points for layout and points to control a surface generated during data prep. The best use of point data on plans placed to control a surface is storm rims. The image shows a manhole that has an elevation called out in the plans. There is also a curb inlet with similar properties. The issue is these elements are in a street that is governed by a vertical profile and templates. If a point is added, it would not be necessary as the street will be correct here. We add points for two reasons: we can verify the elevation is correct, and that point will be labeled and sent to the field for layout.
If that example was a parking lot, the rules would be different. With no overriding cross slope information, we need these to bring water down to the drain. Here we see a grate against a curb in a parking stall. The elevation along the bottom of curb is going to get picked up and paving will drop to make water flow. What is not seen here is layout points. We will talk about those later.
Spirited discussions over beer include how to make the surface look around these inlets. The image above shows a single point at the center of box along the face of curb. Other users feel it important to run points all around the box in order to show that as a flat surface. Here is my take: a small box like this (2 feet x 2 feet) only needs one point. If it gets over that, use points to make it flat. The image below is the same inlet with elevations included to make the entire structure flat. Things did not get messed up with the additional vertices, but it can happen so be careful. Remember, each of these triangles are flat. The first image shows nice flat planes leading to the drain. The additional points made more triangles and they slope in an asymmetrical pattern distorting the otherwise nice flow to the drain. Further exploration brings up some interesting points.
With little change to the surface for a small inlet, there is no need to complicate things. This is flat here so the additional triangles and breakover angles are not huge. If the approach to the inlet was over 2%, it could have become messy.
Another area that benefits from points is controlled site grading. That is (usually grass) areas that need to drain or have structures like a playground. I will use points to make water move where it needs to as well as placing supports for installed items. Something to note here is that points for foundations, or bases, are not usually part of a surface model. The grading around these areas are often below the concrete and would only distort the surface. These would be added to a list of layout points to be laid out when it came time to dig footings.
I use points to “connect dots” and improve conditions. When a point is added, you increase the number of flat triangles thus reducing the breakover angle between each triangle. This also makes each one smaller and smooths out transitions. With each addition of data, you run the risk of screwing things up, be careful. Here are some situations I look for when cleaning up a surface.
In this first image, there is a valley that reduces in depth until it hits a rounded retention. There are steps in the valley and the addition of a break line will improve this. The break line is not the addition of points but a 3D (or 2D) line that is a visual connection of points. The line is only there for your convenience, the TIN connects 3D points.
I ran break lines along the top and toe of the drainage swale. This cleaned things up and now water will flow better. Any time you add points by the addition of a break line, make sure it does what you want it to do. I’ve seen a lot of additions that are not needed for a good model. Surfaces are best when the minimum number of extras are added.
The basis of this article is what we call “named points.” A named point is a point you will most likely list and stake to at some point during construction. They also get included in surfaces as well as used for locating. Cleaning up of the ditch, as shown in the image, brings up an idea. This could be easily laid out as a surface. In this case, there is a concrete liner that gets placed in the swale, and points help to get things right. When the surface looks good, we will add layout points so the form carpenters can easily set the forms for the pour.
Now that the water works the way I want, the addition of points will make a good transition to the field. The image is an example of what I would send, end points as well as a point along line for the bottom of the vee. This represents the outside of the concrete so that becomes the edge of the form. It is better to throw in a point or two to clarify the intent of the plans. Remember, you are in the office in a controlled environment. In the field it’s not as easy to look at plans, specifications and details in cold, wind and rain.
When a point is shot, you are doing it for a specific purpose. That eventual use dictates the collection method employed. GPS is an accurate tool but that changes with conditions and collection settings. A topo point will take a second. When you are shooting top of pipe for as-builts a longer occupation is better for improved accuracy. GPS increases vertical accuracy with a longer occupation of a point. The x, y coordinates will not shift much with increased time.
When you first initialize a site, the time you cook on control points can be as long as three minutes to get a good result. That time would be a waste if you did that for all your as-builts. Know when less can be as effective for the work at hand. I have seen field people not take enough time to get a point collected correctly. Don’t use topo collection for critical locations that are going to be covered up and accessed in the future. That information will eventually end up on a GIS database somewhere and others will use it for planning and excavation. We are making a long-term investment in getting a workable map of our work to make things easier in the future.
I can’t take the high road here. I start as-built collection with correct P Codes (Point Codes) and somewhere along the line I forget to change the code and my great field to finish idea is gone.
- Establish a company standard for point naming. This should be done for layout as well as collection.
- Try to set codes in the field as you collect. If you mess it up, don’t abandon the idea, just get it right again and fix in the office.
- Collect more points than you need and more points of random areas. They will help tell the story when in the office.
- Set up field to finish codes with company standard point naming. This is fluid and will change/improve over time.
Yes, points are part of a surface, but using them to locate and collection later is something you need to do and get good at. I will address field to finish solutions in the future. For the time being, get set up with a smooth transfer of point information to and from the field.
Many years ago, I proposed that machine control would change the surveyor’s role and made it a point to discuss this with many state surveying groups. As a rule, surveyors need to be exact. A circumstance could come up where one would have to defend their work in court. With the need for accuracy, surveyors were not happy with contractors bringing precision equipment onto a site. Some thought contractors were cutting costs by reducing survey crew trips to construction sites. However, the real reason was that a surveyor may have to go back and tell a contractor some of their work was done incorrectly. Every surveyor hates to return and re-pound stakes that got knocked over, so how do they make sure the contractor can perform great work independently?
Survey Builds Data
I have been involved in lively discussions to legal debates over the production of machine control data. Regardless of the state, the answer is always the same: data built by or on behalf of a contractor is not an issue. Once that got settled the question remained, “Who should build the surface you will grade to?”
Survey is solely about points. Load calc points into a data collector and go out and place them on the ground. The contractor connects the dots and a surface is made from the points.
The image at the right shows what we were given in a set of plans. Points found on the plans are placed on the ground in three-dimensions with a stake. The cut/fill to the desired location was marked and the dirt was moved. When things got close, blue tops were placed with the top of the wood stake at finish. Other types have a staple in the top holding the whiskers, a good operator would “polish” the staple and get grade that precise. The difficulty in this method of staking/grading is what happens between the hubs, a low spot or incorrect drainage is easy to miss. Only when a lot was paved would the problems show up. No matter how much spot checking we did, sometimes a spot would get missed.
When I started doing this work, the only frame of reference I had was how things were staked and cut in the field. Because first generation equipment was difficult to use and problematic, training and ongoing support were normal. I spent more time in the field than in the office. We would build the model and I would be in the field for days, to weeks, training crews and getting a better idea of how to leverage the data that I collected.
The knowledge I gained by working in the field allowed me to create workflows that are now commonplace. The other problem we faced was that nobody knew how to build a model, but surveyors felt they were the best option. This is a learned ability and with practice anyone can become proficient, like me for instance. I worked long and hard to figure out how a model works in the office and the field. Coupled with a good understanding of how the mouse clicks transferred to the ground, I began to connect those dots. One of the most frequently asked questions I get is who the best candidate for a data builder is. I find it easier to train a computer savvy field person than try to get a CAD expert to think in three-dimensions.
In time, more people learned how to create good data and software ran ahead to improve commands and performance. The future holds the key to 3D design and implementation of data into the field. BIM has taken the lead due to multiple trades trying to occupy the same physical space. Currently much of that design work is done with CAD technicians producing the 3D models suitable for construction.
The ability to design, (or produce 3D data from CAD and plans) is mature. We will discuss the integration of surveying and data.
As more contractors started to create their own files, surveyors were not building as much data but keeping busy doing the important job of positioning. It’s necessary to understand what a surveyor does, but not actually do it. Surveyors need to understand data but not necessarily know how to build surfaces. Here is what each needs to know about the other.
Somebody must make a model for the machines to work. With model in hand, it’s time to go to the field. Surveyors are critical to any job large or small. I have seen the start of too many jobs by well-meaning contractors placed in the wrong spot or incorrect elevation. The nuances of positioning are complicated, and it is the surveyor who can assist in correct site placement. The GPS lead on the jobsite needs to have some of this ability too. The most important thing is sensing an issue and when to contact survey for work to be done. I have a surveyor friend who ten years ago would build the model and give the contractor a rover with the data loaded. They would start the job and call when they needed something.
I need to be clear; office and field civil construction workers are not doing survey. We are laying out and grading to information the surveyor knows is in the right place and will perform as intended. That is the end point of data and survey working together, so how do we get there?
I’ll run through the process when we work with a client on a typical site job.
- We build the initial model and do the following:
- Fix obvious errors and note them.
- Make grading changes to reflect proper water flow.
- Verify dates and changes to the plans to confirm current versions.
- Report these changes to the contact(s). Usually this is the contractor. As the jobs get larger, we are often asked to communicate directly with the engineers and surveyors and include the contractor in the discussions.
- Responses are received regarding questions.
- Data is updated and work continues.
The data needs to start out as a representation of the finished product. There may be changes pending but not so detailed that we must redo a lot of dirt work. This rough grade file will keep the schedule moving and let the engineers know how long we have until we run out of things to do. Hard deadlines go both ways, stakeholders need to know we are faster at moving dirt and need answers to questions.
Your surveyor is invaluable at this stage, coordinate values need to be correct, the best way to know this is to bring them in early. As hired guns, we communicate with survey crews on jobs all the time. Be sure to do this early and with all jobs.
The next step in confirming data is to bring in control and verify locations and accuracy. Now that things are in the right spot and the data is close to correct, we can send the data to involved parties and gather input. Don’t expect a lot of information, everybody is busy, and most don’t have the time to review your data. It’s more of a courtesy.
I have often been involved in some very detailed discussions about survey’s role on a job. I am an expert witness regarding disputes that sometimes involve surveying. I am no surveyor but have a good grasp on the practice. It takes time to be good at this and I leave it to the professionals.
The surveyor needs a plan for what they will do on your site. This prevents duplication of effort as well as ensuring it is going correctly. Here is a list of things to get right.
- Understand what a site calibration (localization) is and what the report means. These numbers are critical and you need to understand them. When the surveyor is using different equipment than you are, you will need to perform this on your own. Compare the results to theirs to verify.
- Know the difference in collection times. Sometimes you can walk and click, and other times you set up the bipod and cook for a minute. This affects accuracy and a few more seconds on various point types will be rewarded.
- Respect procedure. Don’t take phone calls or talk to people on site when you are involved in critical tasks. When the surveyor tells you not to bother them now, it’s not because they are a jerk. They are in the zone and don’t want to miss something. When you are laying out curb points for example, always do things the same way. For example; I always do PC, RP, PT. Pick your method and stick with it. Here is a simple curb layout. This is what I want to see when I’m laying out.
- Perform daily check-ins. Know that when you start your day you are as correct as you were yesterday. Do this for rovers and machines.
- Share and listen. The information needs to go to the surveyors and engineers for review and comment. Again, you will not hear much, it’s just good to let them know what things look like in the field. This is a big advantage on remote jobs.
To wrap things up, learn enough about the other person’s job for better communication and efficiency. None of us can do a job that we are not trained for, but an understanding of the roles around you will go a long way in making things run smoother.