Hi,

I'm looking at the scan angle metadata from my lastest flight. Values range from -36 to 112. I understand that the scan angle is usually the combination of the angle of the laser plus the angle of the drone, at least for lidars that are fixed to the bottom of the drone. Hence, you can get scan angles outside the FOV spec. However, the L2 is mounted on a gimbal, which should keep the lidar pretty close to nadir. Presumably, the IMU's are mounted in the lidar body. Can anyone tell me then why the scan angle falls outside the [-40,40] range that would be expected?

Additionally, is there any way to convert these scan angles to laser-only angles, perhaps with the IMU data?

I wonder how you manage to get 112


With Terrascan you must be able to achieve what you need.
However, you can also do it manualy with SBET.OUT file and SMRMSG.OUT located in the Terra folder.

LV_Forestry Posted at 8-22 22:02
I wonder how you manage to get 112

Thank you. I've been investigating the SBET data and it can definitely help.

I understand that in the original las specification the scan angle rank was defined to be relative to the surface normal but since the lidar is always at nadir I also don't understand how these values are arrived it. Since I don't know that I'm not sure what method I can use to correct the scan angles. I may not have to correct them, if they are truly surface normals, but then, like you, I don't understand how we got 112. There was some wind. Perhaps the gimbal was not able to reposition the lidar unit fast enough?

I used a gps_time mask to extract flight lines and the scan angle rank is in (-36,35), which is fine. The lidar unit must be bumping around as the drone turns. Thanks for the heads up about SBET.