Visibility map creation takes a long time

The CAU example street canyon takes a very long time to determine the visibility map.

The following scenarios were tested and can be recreated with the attached ini file (paths might have to be adapted).

skp + wrong coordinates -> long runtime
dae (streetCanyon3.dae) + wrong coordinates -> quick
skp + correct coordinates -> long runtime
dae (streetCanyon3.dae) + correct coordinates -> quick
dae trianguliert (streetCanyon2.dae) + wrong coordinates -> exceptionally long runtime