At its core, land surveying is the practice of measuring 3D points on a piece of land. Property owners, construction companies, and regulatory agencies all use land surveys to learn the lay of the land. It’s an important step in assessing any property for future development. And with the help of drones, it’s never been easier.
In this beginners guide, we’ll go over what a drone land survey is, its benefits over traditional land surveys, and the different types of mapping and measurement data it can deliver. Whether you’re a project manager, a geographic information system (GIS) professional, or simply want to learn more about the benefits of drones in land surveying, this guide is for you. Let’s get started.
Table of Contents
What is Drone Land Surveying?
Drone land surveying is the use of unmanned aerial vehicles (UAVs) to evaluate large plots of land. When equipped with high-tech, downward-facing sensors and cameras, a drone can quickly capture images and data on the terrain below it. Then, advanced mapping software processes the drone data and turns it into high-quality 3D maps and models that accurately represent the land’s geography and topography.
As you can tell, a lot of coordinated technology goes into drone surveying. On the data collection side, you have the drones equipped with RGB and multispectral cameras or Light Detection and Ranging (LIDAR) lasers that can rapidly collect high-quality images of a property from different angles and tag them with geographical coordinates.
On the data processing side, you have advanced mapping software that uses photogrammetry techniques to compile drone images into geo-referenced orthomosaics and 3D models. These are corrected for lens distortion, camera tilt, and topographic relief to give you a highly accurate representation of the land that you can use to measure true distances and exact volumes.
Of course, not every land survey is the same. Some will deliver different data depending on what’s needed. But broadly speaking, there are two main types of land survey:
“Any measure that saves time will move the project one step closer to meeting scheduled deadlines and help reduce the cost of recent downtime.”
-Ian Smith at DroneDeploy
- Boundary surveys (aka cadastral surveys) locate and detail exact property boundaries with natural or artificial reference points, so you can have an up-to-date map for future reference.
- Topographic surveys add another layer of information by including land elevation measurements. You’ll need these before making any improvements to a property in the form of buildings, parking lots, landscaping etc.
Both boundary and topographic surveys provide valuable information needed across many industries. Stakeholders in construction, roofing, oil and gas, renewable energy, and mining all use land surveys before beginning any land development project. The detailed maps and measurements are crucial to starting construction.
Traditional Methods of Land Surveying
Of course, land surveys were around long before drones. Even the ancient Egyptians surveyed the land before building the pyramids.
Since then, heavy hardware like total stations and theodolites have been used to measure horizontal and vertical distances between points. For higher altitudes, some use rope and scaffolding surveying methods. However, these ways of surveying require a lot of time and manpower, sometimes even a whole crew. It can take days or even weeks to see the results. And hiring trained experts to operate such expensive equipment comes at a high price.
Fortunately, drones relieve many pain points of traditional survey methods. For one, drones are incredibly fast. They can capture aerial photos of large areas in minutes. Drone pilots don’t need to carry as much equipment around the survey site. They can launch the drone from one location and let the drone take it from there and perform the survey autonomously. Drone surveyors can also do impromptu flights at short notice. Across the board, drones are faster at delivering actionable survey data.
What's included in YOUR GUIDE...
A Proven Roadmap of Success for Implementing Drones in Construction.
A List of Red Flags to Avoid When Hiring Drone Service Providers.
How to Persuade Your Leadership Team to Leverage Drones on Every Jobsite.
Since drones get the job done faster, they are also more cost effective. You spend less on labor and man hours when it only takes one or two drone professionals to do the job. Plus, drone and mapping software solutions can automate data collection and processing and pass the cost savings on to you. This makes drone surveys far more affordable.
Drone surveys also deliver centimeter-level accuracy. Because drones can fly much closer to the ground than satellites or manned aircraft can, the data they collect is of higher quality. Each pixel on a drone map or point on a 3D model is delivered with precise geo-data that is hard to get any other way.
By using drones, you also minimize safety liabilities. Traditional surveyors have to sometimes walk through dangerous terrain or in tough weather conditions to complete the job. But with drones, nobody needs to be put at risk. Drone pilots can operate the drone remotely and out of harm’s way, as the drone works over the site, no matter the terrain or slope.
Finally, drones are hassle-free. They are an all-in-one tool that can launch from nearly anywhere to cover a large site and reach inaccessible areas. They can also survey without interrupting operations on the ground. So you don’t need to shut down roads or redirect traffic for them to work. Without a doubt, drones are the way to go when it comes to maximizing your overall return.
Types of Mapping Drone Data
That said, drone land surveys can deliver a wide variety of mapping data. Let’s go over what you can expect:
1. Orthomosaic Maps
Orthomosaic maps are drone photos stitched together in post-processing. With the help of building information modeling (BIM) software, drone professionals can compile several hundreds of photos into one geometrically corrected orthomosaic map. The result is similar to the satellite view in Google Maps.
2. 3D Models
3D models add another layer of information to maps. They use drone footage from multiple angles to create a three-dimensional representation of the land that includes the facades of buildings and outcrops and so forth. These are great to have if you want to assess a property in more detail.
“In comparison to classical methods, GPS and total stations, we were probably 30 times faster in terms of capturing RAW data and fieldwork and approximately 5 times faster in delivering the final product.”
- Nemanja Mišević, Technical Associate, Vekom Geo
3. LiDAR Data
Light detection and ranging (LiDAR) technology uses lasers to pinpoint distances, even in the dark or when obstacles stand in the way. The resulting high-density 3D point cloud gives you an incredibly accurate representation of the site.
Besides orthomosaic maps, 3D models, and LiDAR data, drones can deliver plenty of other mapping data to suit your needs, including digital terrain models (DTMs), digital surface models (DSM), and multispectral maps. Drones collect such a high volume of mapping data that there are plenty of ways to use it.
How Accurate are Drone Land Surveys?
When it comes to the accuracy of land surveys, there are several factors to consider. The first thing to know is a drone’s ground sampling distance (GSD). Drone GSD will depend entirely on the pixel resolution of the drone camera. Typically, the more expensive the drone, the higher resolution the camera images and the more accurate they will be.
Then for drone maps, there are two types of accuracy: absolute and relative accuracy. Absolute accuracy refers to how a map compares to the real landscape. It’s based on a geodetic coordinate system that can determine real-world positioning. To ensure absolute accuracy, drone surveyors often use ground control points (GCPs). GCPs are large markers with known coordinates placed strategically around a survey site. They help drone professionals match drone footage with GPS data in post-processing.
Relative accuracy refers to whether distances between map points are accurate relative to each other. In other words, is the drone map internally consistent? Though it’s not as precise as absolute accuracy, relative accuracy is acceptable for most small sites and projects.
To get the most accurate land survey, you’ll need a relative model matched with absolute data. You can do this with quality drone equipment and precise GCP measurements. Together, they’ll produce drone maps with 1/10 inch accuracy.
Drone vs Traditional Land Surveys: Which is better?
If you’re still deciding between drone and traditional land surveys, we’ll help you out by breaking down the pros and cons of each below.
Benefits of Traditional Land Surveys
- Traditional land surveying has established methods for which you may already have equipment and skilled surveyors to do the job.
- Depending on the project, conventional tape measure and rope methods may be more suitable.
- You get a direct visual assessment of the land without any intermediary technology.
Disadvantages of Traditional Land Surveys
- Traditional land surveys take longer and could put you behind schedule.
- Since they take longer, they cost more in labor hours. Plus, professional surveyors charge a lot for using their equipment and expertise.
- Conventional surveys involve more risks. There are more worker safety liabilities to deal with, especially if the land is undeveloped or highly vegetated.
- They require a lot of planning and lengthy phases.
Benefits of Drone Land Surveys
- Drone surveys are fast. They can cover large areas of land in mere minutes. Plus, advanced software can turn drone footage into 3D maps very quickly.
- They are cost-effective. By getting the job done faster and only needing to hire a small one- or two-man pilot crew, you can significantly cut your costs on labor hours, which easily yields a higher ROI.
- Drone surveys are safer. They don’t require as much walking or climbing over dangerous terrain.
- They are highly accurate. High-quality drone cameras and sensors coupled with advanced mapping software gives you insanely precise models and maps that you can trust.
- Drone surveys are hassle-free. Forget about putting other construction operations on pause. Drones can survey from the air while work on the ground continues.
Disadvantages of Drone Land Surveys
- Not just anyone with a drone can perform a land survey. Drone surveys need to be performed by professional drone pilots licensed by the Federal Aviation Administration.
- Drones authorization is required to fly in areas restricted by the FAA, which include areas near airports and government land.
- Drones’ ability to survey is severely limited in bad weather, including winds stronger than 15 mph.
Next Steps: Getting Started with Drone Land Surveys
Now that you know the basics of drone land surveys, you can take your next land development project to the next level.
Here at The Drone Life, we help construction, surveying, and environmental companies make the transition into aerial land surveying. If you’re interested in partnering with us or have any questions, feel free to schedule a free one-on-one meeting with one of our drone pilots today.
What's included in YOUR GUIDE...
A Proven Roadmap of Success for Implementing Drones in Construction.
A List of Red Flags to Avoid When Hiring Drone Service Providers.
How to Persuade Your Leadership Team to Leverage Drones on Every Jobsite.
