Global Mapper v25.0

Can you explain LIDAR scan angle range?

I'm trying to filter LIDAR data based on scan angle so that I only get points that are directly below (nadir) the scanner. Global Mapper suggests that a number between -180 and 180 is required, but I'm having a hard to time understanding what this means.

Is the 0° scan angle straight down, or straight up, or something else? Thanks.


  • By the way, my lidar processing software thinks 0 is straight up and offers values from 0 to 360... So I'm not sure if this is based on a proprietary standard or if scan angle is based on some file format standard?


  • A late answer, but I just stumbled on this.

    For aerial scans, nadir is straight down, 90 is horizontal to the right of the aircraft and -90 is to the left.

    I suspect that your software measures all angles to the right, so 270 in your system would be -90.