A 3D model lets a civil contractor or construction professional perform machine control and layout planning before and during construction. Depth map sequencing and point cloud modeling are two examples of 3D modeling often used in construction. Although the two methods have some things in common, they ultimately have different goals and purposes. A point cloud is usually a collection of data points that form a shape, while a depth map conveys information about the distance between two objects in space.
Learn more about the differences and similarities between point cloud modeling and depth map sequencing below.
What Is Point Cloud Modeling?
Point cloud modeling produces a set of small data points, which exist in three dimensions and on X, Y and Z coordinates. The data points represent a part of a surface in a defined area, such as the area of a construction site. When arranged together, the points produce a clearly identifiable structure.
The more data points in the point cloud, the more detailed the structure and image will be. You can compare the data points that make a point cloud to the pixels that make up a digital image. The more pixels there are in an image, the clearer the picture is.
Point Cloud Modeling Methods
Two methods can produce point cloud models — photogrammetry and Light Detection and Ranging (LiDAR), also known as remote sensing.
Photogrammetry is a relatively old process of collecting information about objects and surfaces. When photogrammetry is part of point cloud modeling, a drone takes multiple images of a work or construction site at various angles. After the drone takes the photos, the images are collected together and processed. Processing the images stitches them together, creating an overlapping picture and allowing you to build a 3D model from them.
While photogrammetry uses images to help you produce a 3D model, LiDAR uses laser beams. Typically, a device that transmits a laser is attached to an aerial vehicle. The vehicle goes up into the air, directing laser beams back to the Earth. The laser beams bounce off the Earth’s surface, returning to the vehicle.
LiDAR measures how long it takes for the laser beams to travel from the surface back to the aerial vehicle. In some ways, it is similar to echolocation, except instead of using sound waves to measure distances, LiDAR uses light beams. The information collected by LiDAR can then be transformed into a 3D model. Once the images or information is collected, the process of transforming them into a 3D model is similar for both photogrammetry and LiDAR.
Often, LiDAR collects more useful information than photogrammetry, particularly if there is dense tree cover over the area being measured and modeled. A photo can’t push through branches and leaves to give an accurate measurement to the ground below. A light beam can travel through the spaces or openings in the tree cover, allowing you to see how far below the ground is.
One drawback of LiDAR is that it can be more sensitive to weather conditions than photogrammetry. It can also have difficulty collecting accurate information when the surface is reflective.
The two methods also vary drastically regarding price. If you are on a budget, one method of capturing information for point cloud modeling might be more appropriate for you than the other.
What Is Point Cloud Modeling Used For?
Point cloud modeling has several uses in construction and engineering projects. You might need to create a point cloud for the following:
- Surveying: Point cloud modeling can quickly and cost-effectively produce representations of roads, bridges and other complex structures.
- Earthworks projects: Earthworks projects, such as excavating to produce a new road or lay pipe, can also benefit from the use of drones or aerial vehicles and point cloud modeling. Point cloud modeling allows your company to keep tabs on a project without visiting the site in person. It can also help improve worker safety on-site.
- 3D models: Point cloud modeling also allows for the construction of more accurate 3D models for a project. The data captured during point cloud modeling allows you to accurately identify and distinguish objects in the area so you can create a precise representation.
Benefits of Point Clouds
If you need to create a 3D model for an engineering or construction project, using point cloud modeling offers multiple benefits:
- Accuracy: A point cloud model is an accurate representation of an object or area. Both photogrammetry and LiDAR allow you to capture enough information to produce a detailed, correct model of a particular area.
- Ease of budgeting: Since the process of capturing information for point cloud modeling is so accurate, you can develop a budget for your project without too much concern about going over or spending more than you can afford. Point cloud modeling also minimizes the risk of mistakes, meaning you will spend less time and money on correcting errors. You will also save time on your project, which translates to cost savings.
- Efficiency: Point cloud modeling is a much more efficient process of building a 3D model, especially when compared to the time and effort it would take to create 3D models by hand. Increased efficiency means your project gets off the ground and can be completed sooner rather than later.
What Are Depth Map Sequences?
A point cloud lets you see every data point used to create an image. A depth map gives you a view of the data points from a particular angle. Another way to look at a depth map is as a 2D image that has been manipulated to look like a 3D image. A depth map has information on the distance between objects in a picture. It’s often shown in grayscale.
After the creation of a depth map sequence, the grayscale image is usually merged with the initial photo. Combining the two creates a third picture that looks 3D.
How to Create a Depth Map Sequence
To create a depth map, you start with a 2D image. Since the goal is to turn a 2D image into a 3D one, the source image must have several layers. Ideally, the starting photo will have a background, middle ground and foreground. To produce the depth map, you’ll need a photo and an image-editing program, such as Photoshop.
Start by selecting areas of the foreground, using the magic wand or another selection tool to trace them. After tracing each section, create a layer. Once you’ve selected and created the layers for the foreground, select the part of the image that makes up the middle ground. After that, select the section of the photo that will be the background.
After selecting and creating the layers for your 3D image, grayscale each layer. The layers in the background should be a darker gray than the foreground layers, which should be the lightest gray. You might find it easier to work if you grayscale the image before you begin cutting out the layers.
Once you’ve produced the grayscale image, you’ll merge it with the original picture in the photo editing tool. The overlap of the two images produces a photo that looks 3D.
What Are Depth Maps Used For?
One use of a depth map sequence is to create 3D advertising images. Another use is for producing 3D models for engineering and construction projects. Compared to a flat image, a depth map lets you see what is around or behind objects in a picture, providing you with a more accurate presentation of the area.
Point Cloud Modeling vs. Depth Map Sequences: Similarities and Differences
The primary feature that point cloud modeling and depth map sequences share is both use images to transform data into 3D models. The two methods give you a way to view information.
One of the differences between depth maps and point cloud modeling is the image’s viewpoint. A point cloud lets you see every point. A depth map only gives you a view of the points visible from a particular angle.
Another way to look at the differences between a depth map and a point cloud is to consider the image’s dimensions. Cartesian coordinates include an X-axis and Y-axis, which intersect each other perpendicularly. X and Y axes are all that is needed for 2D images.
When an image is 3D, there’s also a Z-axis, which intersects the X and Y axes and runs vertically. X and Y are horizontal. With a point cloud, you can see the image from all three axes. In contrast, a depth map only gives you the information found on the Z-axis.
Work With a Data Modeling Expert
Your project’s success depends on what you do with your data. The team of experienced engineers at Take-off Professionals (TOPS) can transform your data into a working 3D model. All you need to do is send us your plans and the CAD files and we’ll take care of the rest. To learn more about our services and the benefits of working with data modeling experts, get in touch with us today.
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Several of my recent blog articles have been on data collection and use. Many readers have responded with the same questions. With data coming at me like a fire hose, how do I safely store and retrieve it? Being married to a professional landscape photographer, I learned years ago about putting large amounts of data in a safe place for future use. One advantage we have is that all our data may not need to be saved forever and a post job purge can reduce overall usage.
I will talk about different data storage methods and their advantages. I will not name companies. A search of product and service types will give you a wide range of options. When working on a project, some of the files will be kept on your local machine. To be proficient after some operation(s) are performed, you can move files to a remote location to stop your computer from slowing down.
Do what you need when a project is ongoing. In some cases, we dedicate a hard drive to a project and then store it after the project is completed. Hard drives can range from 100 megabytes to over 10 terabytes. Disk size for hard disk drives (HDD) can be over 20 terabytes at a reasonable price. Here are the best practices for desk side storage.
- Have a large (2TB+) solid state drive (SSD) for Windows and other programs.
- Have a second solid state drive for file storage. We have added multiple SSD’s for expanded storage. Prices are low and performance is required for data modeling and photogrammetry.
- Keep things on the drive as the project goes along. Remote storage is good, but a lot of files may need to be brought back to the SSD’s to do some more work.
I have not mentioned backup of your local machine yet. We will cover local (somewhere you can get to easily) and cloud backups. Remote backup is also another option.
The easiest way to make sure things are safe is to back up your hard drive and put it in a fire safe. A process that is time consuming and prone to forgetfulness. I do not recommend this as there are other solutions.
Network Attached Storage (NAS)
NAS is the easiest way to grab something, work on it, then put it away safely. As the name implies, you have a large amount of storage that is connected to your network. It is a drive that is labeled as a letter, I use “N” for simplicity. The drive itself acts as a small computer with a disk array for redundancy in case of partial failure. Transfer speeds are generally good making it easy to retrieve and save data. There are other benefits as well.
Another NAS drive can be placed offsite, giving you added protection in the event of complete destruction of one of the locations or its drive. I did this for our firm years ago and had a host of issues getting things set up. There are a number of independent consultants who will do this in a matter of minutes and it is well worth the money. Here is a road map.
- Find a technician to set up a NAS. The brand you buy will depend on what the technician recommends.
- Decide on the amount of storage you want. The technician can help with that.
- You will get two NAS drives. One will go in the office, the other in a remote location that has a fast internet connection.
- Both drives will start out in the office, the initial large data transfer will be easier that way.
- The drives are synced and tested while in one location, this makes troubleshooting easier.
- The second drive goes to the remote location.
- Drives can be set to back up continuously or at a specified time, usually early morning hours when no bandwidth is being consumed
This peace of mind is critical in securing your data information. Also make sure that important accounting data and correspondence gets saved from other staffers and departments in the office. The cost for this is less than you may think, and you can avoid sad stories of lost data and ransomware.
Whenever I mention the possibility of using cloud backup, I often get a response related to security. First, platforms like Dropbox are secure and second, the plans and files you are saving are usually public domain if somebody wants to look them up. How tragic is it if somebody sees the CAD for a subdivision anyway? The exception I will agree is sensitive correspondence, financial information, and most internal communication. Use the NAS for that and trust the rest online. Here is the process.
- Decide on the platform and storage limits. Prices can vary widely so shop around. Security is similar with most so do not let that be an issue.
- Decide on what to sync. I use the sync folder as local access as well because the data resides locally and is mirrored to the cloud.
- Depending on your connection to the internet, you can choose to continually update or pick a specified time. This is usually in the early morning hours when you are hopefully not working, and speeds are good.
- A dashboard for the program will keep you posted with the status of a sync.
This easy solution may be the best option due to the protracted setup of a NAS. If you have followed along to this point, there is still the possibility of accounting and correspondence not being saved. Do not delay the install of a NAS too long.
Purging Stored Data
We never really get rid of information completely. After a time, we save a distillation of information and lock it away. You may also want to check with your attorney as to how long they feel you should have full saves as opposed to the reduced density mentioned. Here are some examples.
- Regarding machine control data, we save the latest file we made in the native software and the last files sent to the field. The pdf’s can be saved as well. Sometimes if they are huge, we will strip out pages outside our scope. Remember they are generally available at the agency responsible for approvals. Let them warehouse it. We do not need the original CAD files.
- Photogrammetry jobs get saved as the point cloud and GEO-tiff. Raw images and initial surface production can go away. With the point cloud we can generate what is necessary in case we need to go back. That will save a ton of space.
- Takeoffs can usually be the program file we used for the numbers. No reports need to be saved as you can run them again. We save the pdf sheets associated with the takeoff as well.
- Job notes and correspondence can get saved in total. They are almost always copies of emails and letters that take up little room. I have spent more time than it is worth trying to decide what should stay and the space saved is minimal.
Well, there you have it. A comprehensive plan for saving and securing data. The pandemic has changed everything and many of you are working at home and need access like as if you were in your office. When I started this company, we all worked remote and were on the cutting (painful) edge of a lot of the previously mentioned technologies. Things have gotten much simpler and integrating some or all these ideas will give you a piece of mind. There are a lot of horror stories out there regarding lost or stolen data. Hopefully, you will not be one of them.
Our previous article on chasing perfection on civil sites covered the balance between a perfect model on screen and a well-priced practical job that performs well. In this article, we further explain the details that we touched on as well as additional tips to use to make a job run smoother.
If you take the approach of creating a ton of data for a jobsite, it takes too much time and will confuse a field user that may not be aware of the enhancements made to their job. Some of our clients have used the following ideas at one time or another but not all of them at once. Another consideration is phasing and machine type.
There are two important things to consider before deciding to use information above a basic model; the benefit of the data in the field and the cost to produce it. Also confirm the desire and ability of field crews to wisely spend that additional work and money. Regarding enhanced data, I can work with two different crews from the same company and get buy in from only one. Culture sometimes is not companywide. You need a champion to grab a new idea and leverage it for real success.
START AT THE BEGINNING
We need to establish a point of departure for my ideas. At the bare minimum, you should present to the field a correct finished surface model showing areas that are going to be worked with a blade. Nothing fancy, but a faithful representation of the intent of the job. I use the word intent with an explanation. It is the intention of all involved to have a good looking well performing site. If the plans don’t reflect it, you are the last line of sanity before something incorrect gets put in the ground.
This basic model is what most companies who do in-house data provide. Office staff are just too fractured to spend too much time on any one job. I know, I’ve been there. When field crews get comfortable with a basic model, they usually want more information to boost productivity.
We will increase data information with a new user as their comfort level increases. The real trick is providing what makes the most impact for boosting productivity.
ENHANCED DATA OPTIONS
I like to produce the most bang for our client’s buck, and the following concepts can get you there. I will go through these concepts in a video as well. A few minutes of screen time can say a lot.
Lines can be either 2D or 3D. Adding the third dimension may work okay for some data collectors but not machines. A 2D line with a surface reference beneath it seems to work in most cases. This will save on data prep time. The exception to this would be for a curb alignment in a parking lot. The top of a curb is only six (6) inches wide; to the inside of the line the elevation drops quickly to the gutter. We will often provide a top back of curb elevation surface that’s three (3) feet wide so the elevation is easy to find.
This broad term represents anything you might usually stake but want to reference at any time.
- Start with the building pad blowup lines and a surface to the extents. We often provide foundation footing trench information. This is usually bottom of footing with vertical steps and varying widths. Pad footing locations and grid layout lines help with larger projects.
- I’ll cover utilities in a separate blog post. There’s too much to list here. As a useful improvement to have on a machine or data collector, utilities are high on the list. 2D water, gas, and electric go a long way in helping the field team plan their trenching. Sloped pipe utilities are best laid out in 3D for improved production. Structures are often a mix of 2D and 3D information. More on that in the video.
I often get into lively conversations regarding subgrades. There are only two choices when it comes to cutting a subgrade; provide a surface file or dial down. We usually try to provide just a finished surface file for several reasons:
- Building additional surfaces cost money.
- When you dial down in a machine and offset a subgrade behind the back of curb the machine does a better job than data prep software. Let me explain here and in the video. Parking lots have variable cross slopes, often changing quickly and greatly. A horizontal offset in a machine correctly projects the slope. It is not easy to do this properly in the office.
Many data collectors and machines show the vertical offset on the screen, so you know when you are off finished grade. We also like finished surface files because they match the plans. This makes it easier to check grades against the plans without the potential for bad math.
With hardscape there are a lot more things you are either responsible for or can just help to move along. When it comes to hardscape items, GPS can help with grading and the initial ground setup. We will usually include layout items that are 2D but beneficial.
- Streetlights: Parking lot lights can be laid out early so underground electrical can go in.
- Parking Lots: We provide layout for parking lot striping and special marking. This helps the striping to move along quickly.
- Playground Equipment: Layout is critical. Setting bases and foundations with technology is a time saver.
Turn lanes are often built during a civil site improvement. When plans were prepared, the topo shows existing pavement elevations. Usually these are not correct as the topo is old or the lane was not shut down and the spots were estimated. Here is how we correct this:
- The contractor will get quality spot elevations at 10 feet along the proposed saw cut line.
- We bring the information into the model.
- Proposed changes are made in the model and sent to the contractor for submittal.
- Approved updates are sent to the field for work.
ENHANCED DATA ADVANCEMENTS
As we become more reliant on electronic data and placing dirt with technology, the idea of enhanced data might be considered standard by many. I will now go over some new and exciting offerings for data. Many of these suggestions are responses to questions that I’ve received. I appreciate the feedback and enjoy the interaction.
One of the biggest advancements we have enjoyed is the use and accessibility of drones and LIDAR. With an easier way to acquire current ground information, we now need to know the best way to work with it. Here are some tips and processes that will help.
The biggest issue we see with using alternate collection methods is platform compatibility. The LIDAR or drone shots do not match when compared in the office. Here is a process to try.
- Use the same control for scanner setup as you did for localization. You will need to bring in control quality points to the site and set up the machine over them. Might be best for your surveyor to add the points.
- When scanning, take some long occupation topo shots of the area being worked to compare at the office later
- TBC has a command called Points to Surface. Use it to see how things look.
- Usually there are greater vertical errors at the edges of scans, perform closer occupations to stop this.
- Never do an adjustment of a scan or tweak the data vertically. Go out and do it again the right way.
- Realize that sometimes LIDAR is not the tool and either use a drone or manually topo.
- Control is critical here. Make sure ground targets are survey grade and reuse the same locations on each flight. You need to pick target areas that will not be greatly disturbed during construction.
- Regarding light, flight time is important. Fly in the same sun angle every time, and as high as possible.
- Process the data the same every time. If you send it out, this may be harder but set the same options for each flight.
- Run the Points to Surface command in TBC. Carlson has the same type of command as well.
- Look for areas that are not in tolerance. Do not adjust anything; just go fly again tomorrow.
These tools are now affordable and easier to use than ever. Your use of the surfaces created and enhanced data will improve efficiency and profitability.
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.
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.
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.
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.
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.
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With 3D technology, earthwork modelers and surveyors can view virtual models of proposed projects before the groundbreaking work commences. Different types of software can generate such visualizations, and this has led to the BIM vs. CAD modeling debate. Both options have their benefits and supporters.
For anyone new to these software tools, it’s important to be able to make an informed BIM and CAD comparison. Therefore, it is crucial to understand the pros and cons of BIM and, likewise, the pros and cons of CAD.
What Is BIM?
Building information modeling (BIM) is a set of software tools that make it possible to visualize a design idea with realistic dimensions from a multitude of angles. With BIM, design teams and work crews can have a virtual experience of a building, road, bridge or monument before the structure is physically constructed. For all the parties involved in the conceptualization and construction of a structure — including earthworks and surveying crews — BIM provides the following benefits and features:
1. Conflict Prevention
BIM tools allow earthwork teams to determine whether any clashes might occur between a proposed design and the underlying conditions of the site in question. For example, if a building would need deep plumbing yet the ground being excavated sits over thick roots and rocks, these discoveries can be factored into the design plans to avoid issues down the line.
2. Error Reduction
BIM technology makes it possible to catch any errors that initially appeared in a proposed design before the construction work goes into effect. For example, if earthwork crews discover that the dimensions of a proposed building design will not be feasible at the prospective site, planning crews can take this information into account and either make adjustments or change the overall plan.
3. Use in Construction
BIM software is used by construction crews who break grounds on new lands to establish the foundations of roads, highways, buildings, bridges, monuments and structures. The software makes it possible to determine which structures will ultimately work over certain types of soil, thus making the processes involved with earthworks easier for planners and crews.
4. Use in Ground Logistics
BIM software contains a range of features that specifically outline the logistics of plumbing at a given work site. This way, planners can determine whether the stretch of land in question will be suited for the project at hand, be it a tall office building or a wide industrial facility.
5. Use in Planning Piping
BIM solutions make it possible for earthworks crews to determine which type of piping will suit the stretch of land in question. The software can be used to create 3D piping designs that take into account the diameters and lengths necessary to transfer water underneath a proposed building site to the nearest reservoir.
6. Collaboration Tools
BIM solutions offer collaborative tools that make it possible for earthworks teams to interact with other teams in the construction process, from designers and architects to builders, planners and investors. Collaboration tools include communication technology that works across different platforms, allowing cloud-based branches to interact with more traditional departments.
7. Visualization Technology
BIM tools make it possible to visualize a site in 3D and determine how a potential structure will appear from the ground up at a given site. Based on the position of the proposed structure, the tools allow earthworks and construction crews to determine how sunlight will hit the walls of the building or factory and potentially light its interiors.
8. Step Sequencing
BIM software programs arrange the building process in a series of steps from the ground up, including the logistics involved for earthworks crews. The tools can be used to determine how wide the clearance will need to measure for a proposed structure and how deep the ground will need to be broken to support the height and plumbing needs of the building in question.
9. Advanced Features
BIM solutions go beyond 3D technology to make a full-scale planning sequence for earthworks and developers. In new and upcoming versions of the software, BIM is activating tools in 4D, 5D and 6D, giving users the ability to visualize cost logistics in tandem with design concerns. These more advanced features also make it possible for users to determine the thermal and acoustic properties of a proposed building on the site in question.
Potential Issues With BIM Software
On the downside, BIM has yet to be developed to the point of universal compatibility across all branches of the construction industry. Companies and crews that have fully embraced the technology may have problems communicating certain ideas, information and visuals with cooperating entities that still rely on older technology.
Due to the relative novel nature of BIM technology, expertise in BIM software is a relatively small field. Consequently, there are few technicians to consult when users need outside support on a given issue.
What Is CAD?
Computer-aided design (CAD) is a set of software tools that allow designers to create 2D and 3D virtual models of buildings, structures, machines and parts. For surveyors and earthworks crews, CAD makes it possible to review a proposed structure before commencing work on the ground. The features as well as pros and cons of CAD can be summarized as follows:
1. Enhanced Visualization
CAD software makes it possible for designers and project developers to visualize a product or part in advance of its production. The software can be used to examine a proposed design from a variety of angles, both inside and out. Whereas conventional designs offer a flat illustration of a proposed idea, CAD makes it possible to step inside of a design and view it from a 360-degree perspective.
2. Improved Communication
CAD allows developers to communicate about the logistics and dimensions of a given design and make improvements as discoveries come to light. For earthworks crews in need of new tools and machines for an upcoming set of tasks, CAD provides an easy way for designers to communicate with team supervisors.
3. Use for Structural Engineering
CAD software accommodates the various aspects of structural engineering. Moreover, most CAD programs offer functionalities that apply to specific industries and the various branches that the projects entail. For projects that involve railroad, tunnel or freeway construction, the design features take all the dimensions into account as the design team drafts a 3D visual of the proposed structure, which earthworks teams can then examine and use to visualize the intended finished project.
4. Use in Earthworks Logistics
When the design for a proposed building, road or bridge is created on a CAD platform, the visualizations that the technology provides makes it easier for earthworks crews to foresee how the finished structure will look from the ground up. This knowledge can then be compared to the findings of work teams as they survey the land in question and prepare to break ground.
5. Accurate Design Specs
CAD platforms make it possible for civil engineers to generate maps and analyze specs across a stretch of land. This research enables better-informed designs for railways and tunnels, thus reducing potential errors and costly redrafts down the line. This information can then be communicated to earthworks crews, making the overall plan more efficient and easier to bring to fruition.
6. Input and Feedback
CAD platforms allow conceptualists to take a raw idea and turn it into a three-dimensional design. This allows different branches of a development team to mutually review a proposed design idea and make suggestions that can easily be implemented. If an earthworks supervisor spots an issue with a proposed design, the designing engineer can immediately take this feedback into account.
7. Advanced Tools
CAD software comes equipped with various design tools that facilitate ease of use and also make it possible to achieve visualization effects that would not be possible with a flat illustration. For example, both 2D and 3D CAD software contains a gripping feature that allows designers to pull, alter, adjust and reshape the dimensions of a proposed structural concept. If an earthworks supervisor reports that a road or pavement design requires an adjustment in width, a grip tool can help employees quickly make those changes.
Potential Issues With CAD Software
CAD software typical takes time to master, meaning that the cost of training can be high and the learning curve can be long. Moreover, the number of CAD experts is relatively small, which can make it difficult to find help if a problem arises.
For any company that has yet to migrate to a cloud server, CAD would be a step removed from that company’s technical infrastructure. As with most new technology, CAD is primarily designed for companies that are up to date on today’s more advanced systems.
What Are the Differences?
A quick rundown of the features of BIM and CAD makes the two seem rather similar. So how do you compare BIM and CAD? The two have some crucial differences that make each more suitable for different types of projects. So what is the difference between BIM and CAD?
CAD was developed to design virtual models for everything from appliances and furnishings to automobiles and rolling stock. CAD software tools are used to create 3D visualizations of the surrounding bodies of vehicles and tools, as well as the smaller parts that comprise the motors and fans inside each machine.
CAD can be thought of as a computerized sketchbook in which designs are hashed out and ultimately refined in 2D and 3D renderings. Each line works independently of one another and can be adjusted or eliminated without affecting any of the surrounding or underlying lines in the design. Therefore, if the design for a parking lot or road requires an extra three feet on one side, you can adjust the line that represents that side accommodate the change in dimensions.
Complex CAD designs consist of numerous sheets, each with separate lines that are overlaid in a virtual file. If a design needs to be adjusted, you must adjust all the layers affected by this change individually. If a design consists of many layers that must each be adjusted in tandem with the others, making revisions can be complicated. With CAD, there is no way to synchronize the layers into a single-action item for a multi-layer adjustment.
BIM was developed more exclusively for the virtual design and multi-dimensional visualization of proposed building ideas. As such, the tools are designed to digitally render the complex dimensions of all the parts that comprise the interior and exterior of a residence, factory or office building, including the walls, stairs, doors, windows, ceilings, plumbing, wiring, lighting and ventilation.
A major difference between BIM and CAD is the interactivity of the different dimensions during the editing process. In BIM, the dimensions that comprise an object are interconnected. Therefore, any adjustment that needs to be made in a building design, such as the width of a wall or corridor, can be done in a single edit.
In BIM, the dimensions of a given detail can be synchronized to all instances of the detail in question. For example, if the windows on a building are initially designed to be 3.5’x5’ and need to be adjusted to 4’x5’, you can change all the windows on the virtual building with a single adjustment.
What Is Right for Me?
Earthwork modeling and surveying teams can use BIM software to determine the ground dimensions of a proposed structure. Surveying crews can take a proposed building design and determine whether the chosen piece of land is right for the project in question. Earthworks modelers can then use the software to design the depths and dimensions at which ground will need to be excavated to set the foundations and build the sub-levels or layers of the building, factory, road, parking lot or structure.
For earthwork modeling, BIM tools can facilitate a more efficient flow of tasks because the software is designed to edit complex dimensions in a few steps. When all the dimensions of a construction layout are taken into account, BIM offers a more complex set of dimensions from various angles in a virtual preview. This way, all the parties involved in the construction can review the measurements beforehand and make suggestions or edits in advance of the project’s starting date.
BIM software tools can be especially advantageous for earthwork modeling of designs that consist of multiple levels. For example, if a development team proposes a multi-level courtyard across an acre of land, BIM tools can be used to accurately render the dimensions of this idea. The surveying team can then review this virtual design and provide suggestions and feedback. Construction crews can then reference this final design when it comes time to break the ground for the courtyard.
Data Preparation by Take-Off Professionals
For complex site work, it’s crucial to have 3D models to preview before construction begins. Take-Off Professionals is staffed by a team of expert engineers who develop 3D machine control models for earthworks projects as well as perform construction material takeoffs. Regardless of the size and complexity of the project in question, we can prepare data the way you need it. Contact Take-off Professionals to learn more about our 3D modeling services.
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As a professional involved in architecture, engineering and construction (AEC), you’re likely familiar with quantity takeoffs. The term has been around a long time in the building industry, and it reflects an important part of the planning process. Quantity takeoff requires a highly specialized skill set to do data management correctly.
This crucial step in a project’s early stage can make or break success. In fact, improper quantity takeoffs can underestimate or overestimate construction costs, causing inefficiency in the entire construction chain.
It can be detrimental to any job when required material amounts and realistic pricing values are overlooked or duplicated. The key to successful construction data collection is thoroughness and accuracy.
What Is a Quantity Takeoff?
Explaining what a quantity takeoff is in construction is relatively straightforward. Essentially, a quantity takeoff refers to estimating materials. You review the project plans and take off information about what physical materials the architect, engineer or draftsperson specifies to assemble the project.
Quantity takeoffs in construction have many other names, including:
- Estimating takeoffs
- Construction takeoffs
- Earthwork takeoffs
- Material takeoffs
- Material estimating
- Material counts
- Quantity surveying
Regardless of what you call them, quantity takeoffs are material-specific. As a rule-of-thumb, quantity surveyors or takeoff specialists don’t account for other project needs like labor, overheads, permits, insurance, equipment or incidentals. They stick to isolating material requirements and transposing that information into cost-based estimates.
Technology has changed the quantity takeoff method, and for larger construction companies, computerization has been invaluable.
Today, advanced processes like Building Information Modeling (BIM) raised the technological bar with more complicated systems than used in the past. However, computers significantly increase estimation accuracy. This helps to solve the age-old problem of low productivity and excessive waste elegantly outlined in a commissioned report by the Economist Intelligence Unit.
Computer-aided design (CAD) programs revolutionized the building industry. Many modern projects are built twice. They start life as virtual environment models that work out the bugs and then move forward with reduced-risk structures in the real environment.
While computerization has increased takeoff accuracy and speed, the human element in quality takeoff examples can’t be replaced. Digital takeoffs are still at the mercy of human operators and interpreters just as manual takeoffs are. Today, we still rely on two quantity takeoff methods — manual and digital.
1. Manual Material Takeoffs
This is the oldest and simplest material takeoff form. Manual material takeoffs involve the estimator taking physical plans or blueprints and carefully detailing every material type and quantity specified on the construction drawings. This is a time-consuming data management process and prone to human error. It’s the estimator’s knowledge of materials, experience in estimating and skill in taking off material quantities that ensures accuracy. With manual methods, there’s no substitute for attention to detail.
2. Digital Material Takeoffs
Performing material takeoffs through computer analysis and database application is relatively new in the construction industry. The first effective CAD-based programs date back to the late ’80s and ’90s, and their sophistication quickly evolved to include computerized building models integrated with digital takeoffs. Digital takeoffs are superior to manual methods for large and complex projects because of their speed and thoroughness. The qualifier is the takeoff technician being properly trained and proficient with the software application as well as highly attentive to applying the takeoff information into cost-based results.
Quantity takeoffs can be complex and involved processes. However, they have a single purpose, and that’s accurate data management. Whether you employ manual takeoff personnel or equip them with the latest digital takeoff program, the outcome must be an accurate list of all materials required to complete the project. It also has to conclude with a meaningful price structure.
Who Needs to Do Quantity Takeoffs?
Everyone involved in organizing the front end of a building project needs to do quantity takeoffs. Material takeoffs aren’t a tail-end qualifier. They’re a critical step that begins the bidding process to propose a realistic contract based on accurate material and financial information.
No matter how small or large your project scales, you have to start by calculating how much it will cost and how much material it will need. That’s whether you’re looking at a single residential unit or a larger subdivision undertaking with compounded earthworks, utilities, road surfaces and integrated above-ground structures. It begins by taking off materials, understanding what you have to work with and predicting the eventual price.
Architects, engineers and construction managers aren’t the only people needing to do quantity takeoffs. No matter what industry you’re in, if you build anything at all, you’ll require material calculation and price estimates. Here’s a list of professionals who need to do material takeoffs:
- Urban master planning and smart city designers
- Tunneling and subway architects
- Residential home builders and renovators
- Rail and metro transportation engineers
- Offshore and marine architects
- Landscapers and landscape architects
- Highway and road engineers
- General contractors and construction managers
- Energy and utility contractors
- Civil, mechanical and structural engineers
- Architects and all building designers
Conducting a quantity takeoff takes skill, patience and powers of observation. It also takes a lot of experience. Quantity surveying is a high skill and a vital component to support project proposals. In fact, material data estimation is such a critical part of construction that many managers retain specialized independent takeoff professionals to do quantity takeoffs for them.
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How to Do a Quantity Takeoff
Like every facet of infrastructure in building construction, quantity takeoffs are a process. Learning how to do a material takeoff is a skill people can potentially manage if they have the time and resources to train in their system and then allow field time to polish their skills.
Learning in the field can be expensive. Humans are prone to error and manual takeoffs are especially open to misinterpretation, omission and wrongful calculation. So are digital takeoffs if the source input is wrong or the program operator fails to apply sound principles.
There are two ends to ensuring quantity takeoffs are sound and therefore meaningful. Deviating from either path can result in mistakes that can compound errors. An input error is sure to create a wrong end-calculation, and a bad output mistake can have equally damaging effects on money, time and inefficiency.
Getting a quantity takeoff correct is a matter of following a proven process. This formula has been around for years, and it’s the same method whether you use manual or digital takeoff methods. These are the two parts of doing an accurate quantity takeoff:
Proper material takeoffs begin with inputting accurate information into the plans. Whether your draftsperson still hand-draws blueprints or your CAD operator creates multi-layered, three-dimension building models, your takeoff technician is paramount to managing data. This starts by inputting precise information onto the blueprints or into the computer-assisted takeoff software.
Your takeoff personnel only have so much control over what they’re given. Normally, a designated estimator won’t prepare the original concepts, working drawings or CAD layouts. Others in the building chain usually design and specify projects. However, an astute takeoff tech can spot irregularities and account for them during their data management. This is a critical control in the input stage.
Performing material takeoffs is core to the data management output stage. Output turns concepts into physical entities, and this is where accurate material estimation is essential. Putting out hard figures from software printouts creates solid estimates, which are the foundation for successful bids.
Here is where your takeoff person or team has control. Setting aside errors and omissions, your material takeoff relies on a system of identifying materials, quantifying them and then attaching data to a price schedule. This systematic approach, if done right, results in a fair an accurate proposal to move the project forward.
Construction data management professionals take material takeoff output and put this information into schedules based on valid pricing structures. In small-scale projects, estimators might use values based on local suppliers or subcontractors. In large building proposals, estimators often use national pricing. Takeoff professionals know where to look for quality data to use in a quantity takeoff.
What to Look for in a Quantity Takeoff
For the most part, doing a quantity takeoff is a mathematical exercise. You extract or extrapolate material figures on the input side for the takeoff quantities in civil engineering. On the output end, you reference your material figures to values. This creates a base for a total project estimate which adds in additional costs for labor, equipment and overhead.
You’ll hear the term “quantify” used in material takeoff discussion. This is the name for identifying quantities of material being estimated. It might be the quantity of cut and fill required for earthworks. Or, it might be the quantity of pipe, steel or lumber necessary to complete a structure.
Quantity surveyors or material takeoff professionals have a special challenge. They have to turn two-dimensional plans into three-dimensional images to quantify them. Accurate quantity takeoffs come from both the two-dimensional and three-dimensional worlds.
With manual takeoff methods, the surveyor needs to think two and three-dimensionally and visualize the concept. Digital takeoff methods relieve a lot of this spatial load, but a technician still has to manage that data. Here are the base formulas takeoff professionals use to look for and quantify construction materials:
- Unit count: This is the simplest takeoff task, yet it’s easy to miss something in a unit count. When planning a building, estimators will count single items such as light fixtures, pipe fittings or door knobs. They calculate the total unit figures and multiply by unit price to achieve a gross total.
- Linear length: Total lengths or runs are specific to materials like lumber, steel and piping. These building products are difficult, or nearly impossible, to unitize. Estimators will add up the combined linear lengths of materials in this category and also add a gross value to it.
- Surface area: Accurately estimating surface area materials is still a two-dimensional task. It doesn’t matter if it’s flatwork stones, floor coverings or roofing materials. The calculation is length times width, and this total gets quantified to a value.
- Cubic volume: Here’s where the three-dimensional reality enters the material takeoff business. Earthworks, concrete pours and insulation are prime examples where you’d use a cubic volume takeoff. This is length times width times height, and it’s applied as a unitized number on a value column.
- Physical weight: Calculating construction by weight often happens in addition to other takeoff quantification. You might hear pounds of steel or tons of backfill. Calculating physical weight is necessary when accounting for transportation costs.
Although material takeoff professionals pay strict attention to their two and three-dimensional calculations, they realize their figures eventually support two more construction dimensions. Time is an additional dimension on construction projects, as is cost. Because of time and cost, it’s vital to make sure material takeoffs are done right.
Why Ensure Quantity Takeoffs Are Done Right?
The United States construction industry generates huge costs and consumes massive time. American construction projects generate billions of dollars and employ millions of workers. Because of the money and people affected, it’s important to get material takeoffs right.
You have two main material takeoff options. The first is using the old and antiquated manual method. The other is using a modern and more accurate digital takeoff system. Your choice might depend upon how much time you have and what the cost of a digital takeoff system will run you.
Comparing time and cost against accuracy might be a tough data management decision. Fortunately, you have a third choice. This one makes a lot of sense when you’re under a time constraint and demand estimation accuracy.
It’s turning to a material takeoff professional to estimate for you. These experienced construction experts make sure your takeoffs are accurate, thorough and dependable. You can trust them to support your bids and your business.
Contact the Take-Off Professionals for Help
We’re Take-Off Professionals (TOPS). We’re a team of experienced and knowledgeable engineers who will produce accurate data so you can manage your business and build your projects without construction estimation worry.
TOPS offers takeoff services to meet your individual needs. You might be a small-volume builder needing a simple material list to complement your proposal. Or, you might require a comprehensive plan for cutting, hauling and filling earthworks. Whatever your need, TOPs can help improve your productivity by ensuring you have the sharpest information based on the best material takeoffs possible.
Professional material takeoffs increase your bidding accuracy and work efficiency. This results in saved money and greater profits. For more information on how we can help with our quantity takeoff services, call the Take-Off Professionals today at 623-323-8441 or connect with us online.
Surveying has changed substantially over the years — what used to take months of observation, measurement and geometrical calculations now takes a few hours or days thanks to the introduction of GPS technology. In fact, the surveying industry was one of the first to utilize GPS technology, recognizing the potential benefits of the technology. Today, surveying professionals rely on GPS to provide accurate and reliable data for clients across a wide range of industries and applications. Despite the widespread usage of GPS technology in surveying, however, it’s not a topic many know about — that’s why we’re here to explain the GPS surveying basics.
What Is GPS Surveying?
To understand the GPS surveying process, you need to understand what GPS is. In short, GPS, or the global positioning system, is a satellite-based navigation system. GPS was first developed for military use starting in the 1970s and became fully operational in 1993. Since then, it has expanded its use to consumer and commercial applications.
GPS uses a network of satellites, which communicate with receivers on the ground. When a receiver requests data to calculate its location, four or more GPS satellites will communicate with the receiver, sending the position of the satellite, the time the data was transmitted and the distance between the satellite and the receiver. The information collected from these satellites then calculates the latitude, longitude and height of the receiver. If the receiver is moving, continuous data collection can be used to calculate the changing position of the receiver over time, which can be used to calculate speed. No matter the weather conditions or time, GPS can triangulate the signal and provide a location.
While most people are familiar with GPS and have used it to some degree on their smartphones or car navigation systems, GPS is a powerful tool for commercial applications. It’s particularly useful for the surveying industry. Surveying was one of the first commercial adaptations for GPS for its ability to obtain latitudes and longitudes without the need for measuring distances and angles between points. In combination with other surveying equipment, like the Total Station, GPS technology provides valuable information for surveyors to help develop plans and models for client projects.
How Is GPS Surveying Done?
GPS surveying uses similar technology to nearly any other GPS application — however, how surveyors use GPS differs significantly. The primary differences are in two areas — technology and usage.
- Technology: Surveyors use more sophisticated technology than typical GPS applications to increase the accuracy of the data they collect. The receivers used for surveying are significantly more complex and expensive than those you would find in a typical car navigation system, with high-quality antennas and more sophisticated calculation technology.
- Data Usage: The data surveyors collect from the GPS technology is used differently than in a typical navigation system — instead of using location data for navigation, the data is used for measuring between two points. These measurements are collected then stored, manipulated and displayed in a geographic information system, or GIS, for use in a survey model.
But how do surveyors use GPS to collect data? The specifics come down to the GPS surveying techniques that they use. While the basics of GPS are simple to understand, there are several techniques that surveyors use to make the most of the GPS measurements they collect. There are three primary methods of GPS measurement that surveyors use, which are listed below.
1. Static GPS Baseline
A Static GPS Baseline is a technique used to determine accurate coordinates for survey points. Baseline measurements achieve this by recording GPS observations over time, then processing that data to provide the most accurate result.
The technique works by using two GPS receivers. These receivers are placed at each end of a line to be measured. The receivers then collect GPS data simultaneously for at least 20 minutes — the exact duration of the observation period varies based on how long the line is and how accurate the measurements need to be. Once all of the data is collected, a special type of software is used to calculate the difference in position between the two receivers.
This GPS surveying technique is basic but highly useful and accurate, especially when measuring particularly long distances. Because the GPS data is collected over a long period of time, and the observations are collected at the same time at each end of the baseline, the natural distortions that occur in GPS signals cancel each other out. Generally speaking, the accuracy of Static GPS Baseline measurements are one part per million, meaning that a 30 kilometer distance can be measured with about 30 mm of uncertainty.
2. Real-Time Kinematic Observations
Real-Time Kinematic or RTK Observations are similar to baseline methods in that they are used to measure distances between a base station and a second receiver. The difference, however, is that instead of measuring the location of two points over a long period of time, RTK Observations use multiple points in quick succession.
Like the baseline method, the RTK method uses two receivers, one being a static base station. The other receiver is the Rover Station, which moves to multiple positions during the measurement period. The position of the Rover Station is collected within a few seconds and stored. Once the measurement period is complete, this data is stored and used as survey data.
RTK observations are nearly as accurate as the baseline technique, though they are limited to a range of about 20 kilometers. This method maintains a high level of accuracy by collecting data at the Base Station and the Rover Station simultaneously and correcting data in real time — the exact position of the Base Station is known, so any variations can be used to correct the position of the Rover Station in real time. This method, therefore, can quickly gather survey data for smaller areas.
3. Continuously Operating Reference Stations
Continuously Operating Reference Stations or CORS operate using the same principles as the other measurement techniques described. The primary difference is that the base station is installed in a permanent known location. This allows measurements to be taken at any point in the district using the permanent base station as a starting point.
With a CORS-based system, receivers can be placed anywhere in the local area to collect data. When data collection is complete, the surveyors can combine the collected data with data from the CORS to calculate positions, correcting any anomalies to obtain an accurate position. In some cases, if multiple CORS are available, receiver data may be compared to the data of multiple CORS to achieve even more accurate results.
CORS are commonly used for major engineering projects that require continuous surveying over a long period of time — some examples include local government projects, mining sites and tectonic plate studies for scientific organizations. One specific example is the Australian Regional GPS Network, or ARGN, which uses an online processing system to provide positions that are accurate within a few centimeters in under 24 hours. Some countries even have CORS systems that cover their entire nation, allowing for more accurate and reliable GPS positioning anywhere in the country for both commercial and consumer applications.
Who Uses GPS Surveying?
GPS surveying is a quick and accurate way of mapping and modeling the physical world, from mountainous landscapes to city skylines. This versatility and utility are why GPS surveying is the standard practice for any surveying operation. Nearly any group that needs surveying done will use GPS surveying, including government organizations, scientific groups or commercial businesses. Some of the benefits these groups enjoy from GPS surveying include:
- Flexibility: Unlike conventional surveying techniques, GPS surveying can function regardless of visibility. If survey stations are out of each other’s sight due to line-of-sight issues or weather, GPS technology can still measure their positions and provide accurate location data. This is particularly useful when surveying coasts and waterways with few land-based reference points, which is particularly helpful for nautical navigation and construction efforts. The only downside is that GPS stations need to access satellites with a clear line of communication, limiting the utility of GPS surveying in areas with trees or tall buildings.
- Mobility: GPS systems are fairly mobile, able to be carried inside backpacks or mounted on vehicles to collect data quickly and over a wide area. In combination with CORS systems, mobile GPS survey equipment can achieve real-time data.
- Speed: GPS technology is extremely quick compared to the old surveying techniques that relied on extensive measuring and calculations. Now, GPS provides near instantaneous data and can automatically compare that data to provide accurate results quickly, sometimes even within a few minutes. With faster data, survey teams can get quicker results and organizations can reduce decision time.
- Accuracy: The ultimate question stakeholders are concerned about is the accuracy of GPS survey equipment. Ultimately, it depends on who does the surveying. Poor equipment and inexperienced users can negatively affect your accuracy. However, when using sophisticated GPS technology combined with top-level expertise and high-quality software, you can achieve high levels of accuracy every time.
These benefits are the primary reasons many companies choose GPS surveying specialists for their surveying needs. However, all this data is meaningless without context. For almost all industries, GPS survey data is combined with sophisticated 3D modeling to create detailed, actionable data that organizations can use to plan their projects. This 3D modeling data not only allows companies to visualize and plan projects, but it also allows for 3D model machine control for construction projects.
3D machine control uses positioning sensors to give machine operators feedback on their equipment, directing them in how to use the equipment to achieve the desired results. This technology promises to be the new standard for efficient worksite operations, improving the accuracy of construction equipment on site. For more information about GPS machine control modeling, contact Take-Off Professionals or look through our site to learn about our services.
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What Industries Use GPS Surveying?
Almost any industry that needs surveying will choose GPS surveying for its high level of accuracy and utility. One of the biggest sectors using GPS technology is the construction industry — construction companies need fast, accurate survey results for their projects so they can start and finish projects quickly and confidently. Some of the biggest industries in the construction sector needing GPS surveying technology include:
- Commercial Site Industry: Data is essential in the commercial site construction industry at every level. Commercial site construction companies need accurate, useful data and models to create cost estimates, organize their resources and improve overall efficiency. GPS survey data can help, providing accurate results quickly so that commercial site companies can make decisions that improve their profitability.
- Roadwork and Highway Industry: Engineers and contractors in the roadwork and highway industry need accurate survey data from start to finish. Quality surveys help create accurate models, which roadwork and highway professionals can use to place accurate bids, plan projects and organize their resources efficiently to maximize their profitability. On top of it all, roadwork professionals need to get it all done quickly to minimize the inconvenience and cost to the people using those roads. GPS surveys are essential in these efforts, providing quick, accurate results for models so that roadwork professionals can get to work as quickly as possible.
The key for both of these industries, however, is choosing to work with companies that can help them achieve the results they need. Not only do they need professional surveyors, but they need next-level data modeling professionals to help create effective 3D models that can help them plan more effectively and even make use of 3D machine control. Take-Off Professionals can help.
How to Get the Job Done Right
When choosing 3D modeling consultants for your next project, you need a team you can trust to get the job done right. Take-Off Professionals is that team.
Take-Off Professionals, or TOPS, is a team of knowledgeable and experienced professionals specializing in the preparation of 3D models for site work. Our team of licensed engineers, surveyors and 3D technicians handle projects for large and small projects across the commercial site and roadwork and highway industries, delivering quality results every time. Our innovative processes put quality data at your fingertips, giving you the confidence you need to bid, organize and complete projects while maximizing your profits and efficiency.
Over the course of two decades, TOPS has become a data industry leader, producing an average of 1000 models per year with accuracy to three digits for imperial units and four digits for metric units. Our unique industry experience gives us insight into the concerns of our clients, allowing us to quickly adapt to client needs and address any issue so we can deliver effective, accurate and fast results every time.
On top of it all, TOPS makes your satisfaction our priority. We deliver detailed quotes, accurate turnaround times and top-quality customer service for every project, and we stick to our promises every time. Let us know what you need from your data, and we’ll make it happen.
Interested in learning more about our industry-leading processes and how they can help your business achieve more? Contact TOPS today by calling 623-323-8441 or through our online contact form.
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