Estimated reading time: 16 minutes
Land surveying has been practiced throughout ancient history – from ancient times when establishing boundaries to when they used chain links to make measurements.
Fast forward to now, where there are total stations, RTKs, aerial photography, and remote sensing.
Now there’s a new technology that’s revolutionizing land survey. So, how can you use drones for land survey?
Drones can be fitted with surveying equipment such as RTKs and PPKs for flight-planning and data collection. They can also be designed to work with surveying software such as RAPID and Pix4D to produce 3D models and other deliverables. Unlike planes, drones are cheaper, faster, and easily accessible.
Please keep reading to find out how you can use drones for land survey.
Table of contents:
- What Is a drone survey?
- Why Use Drones for Land Surveying?
- What Kinds of Deliverables Can You Expect With Drone Surveying?
- How Do I Get Started With Using Drones for Surveying?
- How To Do a Drone Survey?
- What Software Do You Use for Drone Survey?
- Top 3 Drones for Surveying:
What Is a drone survey?
Before defining a drone survey, let’s first define land survey.
Land survey is the science and technique involved in making measurements from Point A to Point B in both 2D and 3D.
Surveying provides valuable information in a wide range of sectors, including construction, establishing legal boundaries, identifying areas for setting up buildings, agriculture, and many more.
You must have seen land surveyors around with reflective vests, total stations and RTKs standing on tripods, and reflective prisms. But land surveying is not just conducted from the ground; it’s also conducted from the air using satellite imagery and aerial photogrammetry using aeroplanes.
Now that we know what land survey is, let’s define drone survey. A drone survey is simply conducting land survey measurements from the air using drones.
Most of these drones are fitted with unique navigation and other surveying equipment, as we’re going to discuss later in this article.
Why Use Drones for Land Surveying?
While making surveying measurements from the ground has always been accurate, drones provide a better and cheaper method.
There are some debates about drones’ accuracy in such tasks, but thanks to the latest tech advancements, drone survey can become as accurate as the ground survey. Below are some benefits of using drones for land survey.
What Are the Benefits of Drone Survey?
Easier and Faster:
Traditional land survey involves visiting the site, setting up GCPs (more on this later), and taking the actual measurements from each point.
This can be pretty cumbersome and time-consuming. But with a drone, all you have to do is fly over the area. Some areas may require GCPS, but you don’t have to visit every point physically when conducting a drone survey.
Since drone survey requires less effort, a job that usually takes weeks to complete may be done in a few days without compromising on the accuracy.
Nowadays, drones have surveying software that makes data processing and analysis more manageable than traditional surveying software.
Traditional aerial surveys and remote sensing involve hiring helicopters and hiring qualified personnel. Not all projects could afford that. But drones are way cheaper, even those fitted with high-end surveying equipment.
And as long as you know how to conduct a survey, flying a drone isn’t that complicated.
Some drone survey softwares are programmed to conduct accurate surveys. This means that a surveyor can define the area to be surveyed, and the drone will handle the rest. Some examples of apps that can help you program flights include DroneDeploy and Pix4DCapture.
The other drones also allow you to program them based on your surveying needs. You can also program the drones to repeat a series of activities.
For instance, inspecting crops or a construction project, you can program the drone and save the parameters so that you don’t need to input them every time you want to conduct the survey.
What Kinds of Deliverables Can You Expect With Drone Surveying?
The data format you get from drone survey depends on the type of sensors and the surveying technique. Below are some of the most common deliverables.
If you need a single image for a vast area, you can survey small areas at a time and use the drone survey software to mosaic/stitch the photos together into one image.
3D Mosaic Map:
Through drone survey, you can develop a 3D topographic map for various applications.
Drones are instrumental in photogrammetry, particularly in creating 3D models. With a drone, you can rotate around an object to capture it from different angles.
The more photos you take from different directions, the more accurate the 3D models will be. Besides taking pictures at different positions, drones also have inbuilt GPS systems, leading to more precise positioning of the model.
Using unique thermal cameras, you can analyze areas and create maps showing locations with different heat signatures.
This can be useful when inspecting pipelines, firefighting, and a wide range of applications where thermal maps are required.
LiDar Point Clouds:
Point clouds are sets of points that contain information about objects on the ground. LiDar, on the other hand, is a relatively new Remote Sensing technology that helps map the surface of the earth through laser rays.
And it’s one of the most accurate ways to come up with pint clods when analyzing accident scenes, analyzing forests, agricultural applications, and mine inspections.
LiDar effectively gets more precise info than traditional methods, and drones make it even easier and cheaper. Well explained in this video-
Multi spectral Maps:
Natural light (the light we can see) can only get you general information about crop health aspects. But as you utilize Infrared and other rays in the electromagnetic spectrum, you can analyze the crops’ health, what’s ailing them, and how to fix them. You can fit your drone with multi spectral cameras and get the most out of your analysis.
How Do I Get Started With Using Drones for Surveying?
As mentioned earlier, drones make most professional tasks more manageable, but most professionals often don’t know where to start. So, if you’re considering getting started with drones for surveying, below are some factors to consider.
It would be best if you started by getting legal authorization or the Part 107 remote operator’s license. Hobbyist drone enthusiasts can fly drones without a permit.
But as a professional, you’re flying the drone for economic gain, and you fall under the FAA regulations. Below are some guidelines a licensed pilot should adhere to;
- Pass a basic aeronautical test at an approved FAA station.
- The license is offered to you once you pass the test. This license qualifies you to fly a small drone (a drone that weighs less than 55 pounds).
- Take a test to test your aeronautical knowledge every year.
- Drone crashes that cause damages amounting to $500and or injuries should be reported within 10 days.
- Always conduct a pre-flight check to ensure every part of the drone is working as it’s supposed to.
What Should Be the Technology Used for Surveying?
You can choose between two techs to accomplish your survey – LiDar or photogrammetry. This will depend on the type of data you want to collect, the equipment available, and your budget.
Just as the name suggests, photogrammetry involves taking photos. With a high-quality camera, you take overlapping images and stitch them together before analyzing them.
You don’t need any special equipment. As long as you have a camera and a GPS-enabled drone, you can accomplish photogrammetry. It’s also cheaper compared to LiDar.
As mentioned earlier, LiDar involves using ray pulses. Since these are invisible-light rays, LiDar is perfect for conducting surveys at night or in areas with limited lighting.
LiDar is also beneficial when you detailed vegetation analysis, such as in analyzing forest densities of affected crops since the rays can penetrate vegetation.
LiDar is accurate, too, offering an accuracy of up to 1 Meter while photogrammetry can only achieve up to 5 Meter accuracy.
However, LiDar is quite expensive. A standard LiDar sensor can cost as high as $300,000, and it may cost you up to $400,000 to set up a LiDar system considering you’ll not be using a standard drone. It would help if you had a more powerful drone to handle the payload.
What Types of Drone Are Used for Surveying?
There are two main types of drones you can use for drone survey. There are the Multirotor drones, and there are the fixed-wing drones.
Multirotor drones are the most popular and most commonly used. They can have 4, 6, or 8 sets of propellers.
They’re also straightforward to use. However, their short battery life is a significant drawback. Most of them barely last 30-minutes in flight, which means that you’ll have to purchase extra batteries, which can be pretty expensive. Not forgetting having to stop and replace the batteries can lead to errors in the survey task.
On the other hand, fixed-wing drones are slightly complicated to fly, but they last longer in the air. And they don’t always get damaged in case of a crash landing, compared to multi-rotor drones.
They’re the best when you have large areas of land to survey. They also can’t hover, so you’ll need to get a run-way.
Remember not all drones can be used for land survey. When choosing a drone, make sure it can handle the survey equipment and other necessary payloads.
And make sure the inbuilt system and GPS are applicable for survey tasks. You can also purchase drones explicitly designed for land survey, such as the DJI Matrice series of drones.
There are several drone survey software available designed to provide different results. And below are some key aspects to check before investing in any software;
- Free-trial – Despite what software promises to offer, you can’t be sure it’ll work for you unless you try. So check with the software provider and make sure they offer trials. These can be 7-day, 14-day, or 30-day trials.
- Excellent customer support – If you’re new to drone survey, you’ll need help when using new software. It would be great if the developers offered training tutorials, onboarding programs, and even live chats when necessary.
- User-Friendliness – How easy software is to use depends on one’s expertise. Ensure you can easily navigate the User Interface of the software in question and get the desired results. You can test all these during the Free-trial period.
- File-Export Formats – You may be required to share your surveying work with other professionals or even use it with other software such as ArcGIS or AutoCAD. Make sure the software you choose provides file-export formats that are sharable and compatible with other software in the same field.
- A complete package – While conducting a survey on one software and conducting post-processing on another software may seem applicable. You may experience compatibility issues. It would be great if the software used to plan the survey also offered post-processing.
Always Consider Training:
Flying a drone and using the various payloads is a skill on its own. So whether you’re transitioning from traditional survey methods or are a drone pilot who wants to venture into survey, training is essential.
Schools like Microdrones offer training and support on flying drones as well as using the various payloads necessary for drone survey.
How To Do a Drone Survey?
Below is a detailed step-by-step process on how to conduct a basic drone survey.
Choose your drone:
The first step is to select an appropriate drone for the survey. As mentioned earlier, for professional land surveys over vast areas, fixed-wing drones are the best.
But if you’re looking for a drone that can conduct a survey, take photos, and be used for fun, stick to multi-rotor drones.
And you could never go wrong with DJI drones thanks to their affordability, compatibility with a wide range of apps, and adequate documentation on how to use them.
Choose your survey platform/software:
As mentioned earlier, there are several drone survey software. So chose one that allows you to plan your flight and transfer data for processing or even enable you to post-process the collected data within it.
You can also combine different apps to make sure you get the most out of your survey.
Conduct a Preflight Check:
There are several aspects to check before you can fly your drone. These include;
- Make sure you’re allowed to fly in the area you select. It would help if you had a No-fly Zone map.
- Make sure the weather is favorable for flying. Avoid rain, snow and wind.
- Make sure the drone’s and controller’s batteries are fully charged.
- Check the drone for damages on the hull, motors, and make sure the propellers and all other parts are working correctly.
- Make sure you have enough space on your SD.
Plan Your Flight for the Drone Survey:
This is where you define the path the drone will take and the area to be surveyed. You can draw the area manually from a satellite image. But this is not always accurate since not all satellite images are up to date.
As you draw the plan, the drone will show your location, allowing you to adjust accordingly. Another option is to upload a KML file which is more accurate since it will have the necessary coordinates.
As you plan the flight, make sure you set a convenient altitude. When the drone flies too low, you’ll take more images to cover the area, which is expensive and time-consuming.
The best thing to do is set the altitude based on the area’s size and how long your battery can last. A 100*100 Meters area, with a 10-Metre altitude, will take 10 minutes and produce 150 images. But if you set it to 30 Meters, you’ll only take 50 pictures, and the flight will last two minutes.
Once everything is set, you can take off and capture the images. Luckily, most drones have an automatic takeoff button.
So place the drone in an open area, and click the takeoff button. While the drone can fly autonomously, you will need to adjust the lighting based on the time of the day and weather conditions.
Fly the drone back in case the job is complete or the batteries are depleted. For 3D models, make sure you take more images to make a better and more accurate model.
Review the Images:
Before leaving the field, check the images and make sure they’re good enough for your project. You can remove those that won’t help and retake them if necessary, but don’t leave the field without checking.
Once you’re satisfied with the images, it’s time to upload them to your software of choice. Since the drone has a GPS, the photos will most probably be georeferenced (assigned X, Y, Z coordinates).
Once they’re uploaded, you can select the type of output you want – either 2D mosaic or 3D models or any other deliverable. It may take a while, especially if you surveyed a vast area, so be patient.
What Software Do You Use for Drone Survey?
Below are great software packages to consider;
- PrecisionMapper by PrecisionHawk: This program is excellent for 2D and 3D aerial photogrammetry. It provides a package of different software. PrecisionFlight handles flight planning, while PrecisionMapper handles post-processing and output. It’s available in free and paid versions.
- RAPID:Developed by DroneMapper, this software is perfect for Digital Elevation Models (DEMs) and Orthomosaic.
- Pix4D – This is the best software for all types of drone surveys. The best thing about Pix4D is they offer programs for a wide range of applications, including survey planning, precision agriculture, and rapid mapping for emergency response. But it may be quite complicated, so make sure you’re comfortable with it or consider training.
- DroneDeploy – DroneDeploy is the best for beginners thanks to its user-friendliness. It works with most DJI drones, and it’s also compatible with third-party drone-mapping apps.
- DJI Ground station – This is more of a flight-planning app designed to work with DJI drones. While it doesn’t offer several features like the PrecisionMapper, it’s one of the best flight-planning apps for beginners.
- Agisoft – Agisoft is just a post-processing software. It doesn’t offer flight planning, but you can combine it with the DJI ground station app or any other flight planning apps. Remember the multi spectral and thermal maps deliverables I mentioned? You can produce them with this software, as well as 3D and 2D orthomosaics. It also allows you to integrate Python scripts for in-depth analysis.
Top 3 Drones for Surveying:
Now let’s look at some of the best drones for surveying.
DJI Phantom 4 RTK: Buy Now
DJI is the leading drone manufacturer worldwide, and their drones cut across from toy drones to professional-grade.
The Phantom RTK stands out from the rest in the surveying sector thanks to the RTK (Real-Time Kinematic) system which ensures accurate measurements, positioning, and flight planning compared to the GPS.
Thanks to the 1-Inch CMOS sensor, you can take high-quality photographs, and the 5870 mAh battery ensures a 30-minute flight time. Unfortunately, it’s not compatible with the PPK system.
Yuneec H520 RTK: Buy Now
The Yuneec H520 RTK is excellent software for surveying thanks to the RTK system and the fact that it’s also compatible with the PPK. PPK is great when it’s impossible to communicate to a ground station.
So If you’re looking for a drone that can handle LiDar, thermal cameras, and multi spectral camera payloads, this is the drone for you.
SENSEFLY EBEE X:
This is the best fixed-wing drone for surveying. Featuring a 1-inch 20 MP CMOS sensor, RTK/PPK capability, the ability to handle different payloads, and a 50-minute flight time, you can survey up to 50 acres with this drone.
SENSEFLY EBEE X is also compatible with the Pix4D software. The only issue is that this drone is expensive, and it’s not suitable for surveying small pieces of land.
Here is the comparison table:
|DJI Phantom 4 RTK||Yuneec H520 RTK||Sensefly EBEE X|
|Price||$6500||$3199||$15,00 to $20,000|
|Flight-Time||30 minutes||28 minutes||90 minutes|
|Coverage||100 ha (247 acres) at 182 Metres altitude||N/A||500 ha (1250 acres) at 120 metres altitude|
|Sensor||20 MP 1-inch CMOS||20 MP 1-inch CMOS||24 MP APS-C|
Thanks to drones, land survey has become easier, more affordable, and probably even more accurate. It’s easier to repeat a drone survey in case of any errors when compared to traditional surveys.
I’ve explained how you can get started, the various deliverables you can get from a drone survey, how to go about a drone survey, and even some drone suggestions.
Drone Surveying is not that cheap, but a career in drone survey is still viable as more sectors are still in need of such services.