Aerial survey tips (with a fixed-wing UAV)
Modified on: Thu, 31 Dec, 2020 at 12:37 AM
- Do not set side overlap less than 60% and forward overlap less than 80% to get good quality results.
- Do not be afraid to capture more photos than required, more than required is better than not enough. Later on excessive images can be disabled.
- Do not set too slow shutter speed, otherwise blur can occur due to camera movement.
- Do not avoid to use GCP to improve results accuracy.
- Do not perform an aerial survey of the same area for the whole day. Lighting conditions changes during the day. You may get photos of the same territory with different lighting (for example long shadows from the same structures pointing in completely different directions and having different shapes), so Metashape might fail to find common points on the overlapping photos.
- To achieve better overlap, we can recommend cross-to-cross routes, as shown in the image below.
- Do not perform an aerial survey of forest areas lower than 300 meters above the ground. Trees move due the wind and when capturing from a low altitude Metashape may fail to find common points on photos.
- Do not perform an aerial survey of forest areas in the leafless season. Trees without leaves have a lot of thin structures (tree branches), so Metashape will be hard to find common points on photos and the trees will be poorly reconstructed.
- Do not avoid to perform two cross flights to get double overlap when performing an aerial survey of urban areas and capturing different walls of the buildings.
- Do not capture structures built of shiny and reflective materials in sunny weather.
- In case you need to reconstruct a detailed 3D model, do not use drones with only nadir cameras, use drones with a multi-camera system (nadir + oblique cameras) instead or combine single-camera flights with different oblique camera orientation. Such an approach will help to get proper model and texture reconstruction of near-vertical surfaces (e.g. building walls).
|Nadir cameras||Oblique cameras|
- Do not capture photos with only water presented on it, capture photos with land/water presented in 50/50 ratio.
- Do not avoid to perform a double or triple aerial survey of one area from different altitudes to get good results at waterbodies area reconstruction.
- Do not capture water bodies in sunny weather, otherwise reflections will affect the reconstructions.
- Do not plan a flight without a proper elevation model considered.
- Do not perform an aerial survey of mountain areas lower than 100 meters above the ground.
- Consider performing double or triple aerial surveys of the same mountain area from different altitudes to get good results of slope reconstruction.
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