Question 1

What is meant by drone survey?

Accepted Answer

A drone survey refers to the use of a drone, or unmanned aerial vehicle (UAV), to capture aerial data with downward-facing sensors and both GNSS RTK (real-time kinematic) & PPK (post-processing kinematic) receivers. During a drone survey, the ground is photographed several times from different angles, and each image is tagged with real world coordinates.
 
From this data, a photogrammetry software allows us to create geo-referenced orthomosaics, elevation models or 3D models of the project area. These maps can also be used to extract information such as highly-accurate distances or volumetric measurements.
 
Unlike manned aircraft or satellite imagery, drones can fly at a much lower altitude, making the generation of high-resolution, high-accuracy data, much faster, less expensive and independent of atmospheric conditions such as cloud cover.

Question 2

What are the benefits of drones in surveying?

Accepted Answer

Reduce field time and survey costs:
Capturing topographic data with a drone is up to five times faster than with land-based methods and requires less manpower. With PPK geo-tagging, you also save time, as placing numerous GCPs is no longer necessary. You ultimately deliver your survey results faster and at a lower cost.

Provide accurate and exhaustive data:

Total stations only measure individual points. One drone flight produces thousands of measurements, which can be represented in different formats (orthomosaic, point cloud, DTM, DSM, contour lines, etc). Each pixel of the produced map or point of the 3D model contains 3D geo-data.

Map otherwise inaccessible or unsafe areas:

An aerial mapping drone can take off and fly almost anywhere. You are no longer limited by unreachable areas, unsafe steep slopes or harsh terrain unsuitable for traditional measuring tools. You do not need to close down highways or train tracks. In fact, you can capture data during operation without an organisational overhead.

Question 3

What are drones used for in surveying?

Accepted Answer

Land surveying/cartography:
Survey drones generate high-resolution orthomosaics and detailed 3D models of areas where low-quality, outdated or even no data, are available. They thus enable high-accuracy cadastral maps to be produced quickly and easily, even in complex or difficult to access environments. Surveyors can also extract features from the images, such as signs, curbs, road markers, fire hydrants and drains.

After post-processing with a photogrammetry software, these same images can produce very detailed elevation models, contour lines and breaklines, as well as 3D reconstructions of land sites or buildings.

Land management and development:

Aerial images taken by drones greatly accelerate and simplify topographic surveys for land management and planning. This holds true for site scouting, allotment planning and design, as well as final construction of roads, buildings and utilities.

These images also provide the foundation for detailed models of site topography for pre-construction engineering studies. The generated data can also be transferred to any CAD or BIM software so that engineers can immediately start working from a 3D model.

As data collection by drones is easily repeatable at low cost, images can be taken at regular intervals and overlaid on the original blueprints to assess whether the construction work is moving according to plan specifications.

Precise measurements:

High resolution orthophotos enable surveyors to perform highly-accurate distance and surface measurements.

Stockpile volumetric measurements:

With 3D mapping software, it is also possible to obtain volumetric measurements from the very same images. This fast and inexpensive method of volume measurement is particularly useful to calculate stocks in mines and quarries for inventory or monitoring purposes.

With a drone, surveyors can capture many more topographic data points, hence more accurate volume measurements. They can also do this in a much safer way than if they had to manually capture the data by going up and down a stockpile. Since drones are capturing the data from above, operations on site won’t be interrupted. The short acquisition time enables capturing a site snapshot at a specific point in time.

Slope monitoring:

With automated GIS analysis, it is possible to extract slope measurements from DTMs and DSMs generated by drone imagery. Knowing the steepness of the ground’s surface, the areas can be classified and used for slope monitoring purposes, including landslide mitigation and prevention.

With orthomosaics taken at different times, it is possible to detect changes in earth movement and to measure its velocity. This data can help predict landslides and prevent potential damage to roads, railways and bridges.

Compared to traditional monitoring techniques, where sensors are placed on single points, drones enable more comprehensive data collection. Drones with PPK capability, which do not require laying out of multiple GCPs, are optimal for this application, since these areas are often hard to reach or even dangerous.

Urban planning:

The development of increasingly dense and complex urban areas requires intensive planning and therefore time-consuming and expensive data collection. Thanks to drones, urban planners can collect large amounts of up-to-date data in a short period of time and with far less staff. The images produced in this way allow planners to examine the existing social and environmental conditions of the sites and consider the impact of different scenarios.

Thanks to 3D models, buildings can also be easily overlayed onto their environment, giving planners and citizens an experimental perspective of a complex development project. 3D models also allow analysis and visualization of cast shadows and outlooks/views.

Question 4

What kinds of deliverables can you expect with drone surveying?

Accepted Answer

Orthomosaic Map (File formats: .tiff / .jpg / .png / .kml / .html)

3D Point Cloud (File formats: .las / .laz / .ply / .xyz)

Digital Surface Model (File formats: .tif / .xyz / .las / .laz)

Digital Terrain Model (File formats: .tif)
 
3D Textured Mesh (File formats: .ply / .fbx / .dxf / .obj / .pdf)

Contour Lines (File formats: .shp / .dxf / .pdf)

Question 5

How accurate is a drone survey?

Accepted Answer

At this point, it is possible to reach an absolute accuracy down to 1 cm (0.4 in) and 0.7 cm/px (0.3 in/px) GSD under optimal conditions with our high-end surveying drone and software combination.

Frequently Asked Questions

Frequently asked questions

What is meant by drone survey?

What are the benefits of drones in surveying?

What are drones used for in surveying?

What kinds of deliverables can you expect with drone surveying?

How accurate is a drone survey?

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