ATTENTION: The vectors are given in camera coordinates!
During the measurement, the curved line needs to be remarked to
targetcol.
The command works by splitting the line of sight between the
endpoints into a series of "buckets" and putting the found
voxels into these buckets. The bucketwidth should be chosen
high enough, that a significant amount of voxels fall into
each bucket (otherwise measurement can fail or deliver far too
high results due to slight jitter on the line), but low enough
to approximate the line precisely enough.
For the command to work properly, it is assumed, that the curved
line tangential vector will always be at an angle of -90°..90°
with respect to the line of sight. It is recommended that values
near 90° are to be avoided, as they reduce precision. Subdivide
the line, if needed.