When using the rtarea area command, the total exposed
area is not calculated correctly. This is because the
obscurance checking happens at the region level and
depending on how the model was made, you might have
regions obscuring themselves. Brl-cad should
calculate the exposed area only once even if a
shotline intersects a region (ie. a fuel line) more
than once.
I believe this issue was fixed in 7.14.6 while adding in support for calculating center of area. Please reopen this request if you still experience a problem with how rtarea handles region overlaps.