Structure Scan User Guide
- Nathan Howe
The Structure Scan is a mission type available during mission planning of WISPRGroundControl, as of version 0.9.0. The purpose of the scan is to circle a selected region of the map where a structure resides in the center, with the drone taking pictures as it orbits. The drone will do this multiple times - starting at the top layer and after each completed lap descending to a lower altitude, changing the gimbal pitch, and repeating until it’s finished.
The number of layers a scan will have is dependent on the dimensions of the scan being planned. Things such as structure height and the minimum altitude the drone is able fly will effect the exact number of layers and specific gimbal pitch that is used. This data is used to create 3D models of structures.
As you can see in the image above, the building is centered in the green region to indicate the location of the structure. The white outer ring is the distance from the structure the drone will fly. This plan has an estimated structure height of 45ft, while the drone is only allowed to fly as low as 120ft to avoid trees in the path. WISPRGroundControl has calculated that for these specifications, the drone will fly a total of four laps, with the highest altitude being 187ft.
On shorter structures like this one, the drone may fly most of the laps at the lowest altitude and compensate for the difference between the minimum alt and structure height with adjustments to the gimbal pitch. On taller structures you can expect to see the drone notably higher for its top layer, a greater number of layers and a higher variety in altitudes of the layers. The gimbal pitch is set dynamically based on the calculations made by WGC.
It’s important to note that the minimum distance required from the structure will depend on the structure height entered, and WISPRGroundControl will notify you if your scan distance is too small. This is because the drone must maintain a certain distance proportional to the structure it scans in order to keep the time between photos under 2 seconds. 2 seconds is the length of the trigger speed on the Sony A7R Series payload, which is our primary conductor of photogrammetry and structure scan missions.
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