Is Do-Set-Cam-Trigg-Dist a 3D distance?

Is this distance calculated in 3D or based on horizontal distance only? I have a project that is surveying vertical walls in a quarry. The flight plans are set up to have the copter fly up, move over, then fly down, moving down the wall face. This makes it easier to keep the pilot near the copter.

horizontal distance only, you would need to change that in the sourceā€¦