[Geit]

Originally Posted by msleeper If there would be a way to add this permanently into a map, it would be incredibly useful.

I made this a while ago: http://forums.tf2maps.net/showthread.php?t=15060 - But it didn't work to my liking at the time so I didn't release it here, Once I work out the format of visibilityBitfield I'll fix it up and release it. - Till then the code/database it uses for making permanent annotations is probably the best way to do it.