Digital Terrain Model from Drone Data

Digital Terrain Models (DTMs) represent an important geospatial dataset used in surveying, engineering, construction, agriculture, land development, flood modeling, and other topographic studies. Unmanned aircraft systems offer a highly effective and time-saving method of creating highly accurate DTMs based on aerial images, including details related to elevation and surface characteristics.

1. Collect Aerial Data With Drones

It starts with well-planned drone mapping utilizing high-resolution cameras and accurate GNSS positioning. The use of RTK or PPK drones increases the accuracy of acquired images and helps to minimize the need for numerous ground control points. The flight height, image overlap, GSD, and terrain characteristics should be taken into consideration during mission planning.

2. Process Acquired Images With Photogrammetry Software

Captured aerial images are uploaded into the photogrammetry software and then aligned. After that, camera positions are calculated, and the surveyed location is reconstructed in 3D. Photogrammetric processing allows creating dense point clouds consisting of millions of elevation and surface points.

3. Creation of High Resolution Digital Surface Model (DSM)

A Digital Surface Model (DSM) is created using the processed point cloud, which represents the elevation of the Earth’s surface including all the objects found on its surface such as buildings, trees, vehicles, and others. The DSM becomes the basis of terrain modeling.

4. Classification of Point Clouds

Classification of point clouds means distinguishing between ground and non-ground points. Vegetation, buildings, structures, and other surface objects are classified using automated classification or manually or with a combination of both techniques. Proper classification is important for obtaining an accurate DTM.

5. Creating Digital Terrain Model

Once ground points are separated, interpolation is performed to generate the continuous bare earth terrain. It becomes possible to remove vegetation, buildings, and other surface objects in order to obtain an accurate DTM.

6. Export and Optimize Final DTM 

The final DTM can be exported in standard geospatial data formats including GeoTIFF and implemented in applications like GIS, CAD, engineering, surveying, and remote sensing. The resolution, coordinate reference system, metadata, and file size can be optimized based on project needs.