What is the Drone Survey?
Drone surveying is the survey process of capturing ground level and geographic area data using drones with downward-facing sensors, such as RGB or multispectral cameras, and LIDAR payloads.
Using drone surveying, surveyors and engineers can obtain highly accurate Orthomosaic maps, Digital Surface Model (DSM), Digital Terrain Model (DTM), and contour line maps. Photogrammetry and LiDAR are the most common methods to construct drone survey maps.
- Photogrammetry is done by capturing high-resolution area images, and data, and using dedicated drone mapping software for post-processing to construct the 2D and 3D area maps.
- LiDAR is done by sending pulses of light to the area surface to detect small objects and area features during drone mapping.
Features of Drone Surveying.
1. Ease and accuracy of obtaining survey data.
- To generate survey maps, a different part of the area is captured by the sensors or camera several times from different angles and they are identified with certain coordinates. Then those data and images are post-processed to construct 2D maps, 3D maps, and different models to display highly accurate measurements (area, volume, elevation) of the survey.
2. Efficiency.
- As drone survey projects can be planned at any time in any place, surveyors can set up the project before the field visit, and execute the pre-set project at the field. Also after capturing the area, the post-processing also can be done at any time and any place. So the time you have to spend on the field is reduced and optimized.
3. Low labor cost.
- Project planning is the only step that requires human interaction. That’s also very user-friendly and not complicated at all. All the rest of the steps such as automated drone flight and post-processing are performed by dedicated survey software. So there is no need for other laborers.
4. Low riskiness and ability to survey unreachable, dangerous areas
- As Drone surveying optimizes manpower, there is no risk to labor safety. Also, because drone surveys are done aerially, surveyors and engineers can obtain highly accurate maps of risky or unreachable areas.
How Drone Surveying is done?
Step 1: Project Planning.
The project planning step is all about setting up the drone survey project by customizing the different settings such as total flight time, altitude, flight paths, directions, etc. This step can be performed before the field time and execute the pre-set project when you visit the field.
Step 2: Automated field flight.
Once the project is fully optimized and set according to your requirements, it’s time to head to the fieldwork. Once you visit the field, you can connect the drone to your device, and execute the project. Then the automated flight would start and begin to capture the required images and data to construct the survey maps. These captured data and images would be stored in your connected device. Once the flight is over, the drone would return to the start point.
Step 3: Post-processing.
As I mentioned above, Once the automated flight is over, all the captured images and data are already stored on the connected device. So the next step is to upload those images to the software for post-processing. In the Post-processing, the captured images and data go through the software algorithms and match those pieces and construct the whole map view. This step would take a few hours to construct a complete and high-quality map with accurate data and features.
What are PPK, RTK, and GSPs in Drone Surveying?
PPK, RTK, and GPSs are types of drone surveys that use different techniques and technologies to accurately locate the position of a drone in flight.
- PPK (Post Processing Kinematic Survey): PPK surveying uses GPS correction technology to correct the location data.
- RTK (Real-Time Kinematic Survey): The current location data of the drone is provided in real-time corrections during the drone surveying and image-capturing process.
- GSPs (Ground Control Points): Uses reference points present in the ground whose coordinates are already known.
Applications of Drone Surveying.
1. Land Surveying.
Drone surveys can construct high-quality 2D maps and 3D models of the area displaying land features and information. Mostly used to construct maps of areas with low-quality, outdated, or inaccessible data.
2. Construction.
Drone surveying is a huge thing in the construction industry and is often done to obtain accurate measurements and track the process of construction. Because these survey maps and data can be shared, investors can track the project’s progression without visiting the site, even from overseas.
3. Agriculture.
Drone survey is usually used in agriculture to track crop health data which are farmed on a large scale. Because usually, crop data need to be analyzed so often, this technology is so practical for large-scale crop farming health tracking with less manpower, cost, and time.
4. Urban Planning and Development.
It’s so complicated and consumes time and cost wildly to collect area data for urban planning and development projects. But with the use of drone survey, it’s possible to collect large amounts of up-to-date data in a short period of time and with far less human power. These maps, facilitate site scouting, allotment planning, design, and the final construction of roads, buildings, and utilities. In addition, the data is used for pre-construction engineering studies and transferred to CAD or BIM software to work with 3D models.
5. Volumetric Measurements
As I mentioned above, drone survey maps are not just a simple overview of the area. Those maps contain and display accurate data (area, height, volume) obtain from calculations. Therefore, these drone survey maps can be used for ease of volumetric measurements (calculating stocks in mines and quarries for inventory or monitoring purposes).
Image Credits: WINGTRAONE
5. Slope Monitoring
Orthomosaic maps that are constructed at different periods of time, can be used to detect changes in the earth’s movement and measurement of velocity. Those slope monitoring data help with landslide mitigation and prevention.
Benefits of Drone Surveying.
1. Less cost to start compared to traditional surveying techniques.
Anyone who owns a drone with some considerable performance can start drone surveying. cost of the time, the only cost that you have to bear is just the surveying software (Dronedeploy, Pix4D, DJI Terra, etc) for flight planning and post-processing.
2. The easiest surveying method.
Because all the technical things (project planning, flight planning, executing, and constructing maps) are handled by surveying software, it’s easy to plan and execute a survey in a short amount of time. Also, almost any person can plan and execute a drone survey project after walking through drone survey software tutorials.
3. A faster and more accurate surveying method.
A Drone survey is 90% faster and more accurate than a manual survey. As almost every step of the drone survey is managed and executed by software, it doesn’t take that long to complete a survey.
4. Optimized field time.
Drone surveying is so flexible. Therefore you can plan survey projects from any place, at any time. The only time you need to show up on the field is during the project execution time (Which also just takes a couple of hours). Also after the execution, you can leave the site, because the post-processing also can be done at any time and any place. Just like that the overall field time is reduced and optimized.
5. Less manpower.
As all the hard work is done by the drone survey software (Dronedeploy, Pix4D, DJI Terra, etc), there is no need for the extra laborer and manpower to do the actual measurements and note down data.
6. Ease to obtain accurate data.
As drone survey maps display and contains highly accurate data, surveyors and engineers can directly obtain the area, volume, slope, and many measurements without any calculations and with just a few clicks and drags on the map. And those measurements are so accurate compared with old mapping techniques. (horizontal accuracy is 5-10 cm and the vertical accuracy is 5-15 cm).
7. Safety & Map inaccessible areas.
The fact that drone surveys are done aerially, makes it more flexible for many challenging circumstances such as mapping inaccessible and dangerous areas that traditional mapping technologies failed in. Also because there are no laborers used for in site-work for survey purposes, there are no life risks related to surveying.
8. Easy to share data.
Also, with the help of today’s information technology, these drone survey maps can be shared easily shared with investors and necessory parties easily to track the progression and discuss and take decisions, even without visiting the site every day.