Just a quick update this time. I thought I should mention that I have found some unexplained visual errors in parts of my map due to the use of my skip program (from the below update). What happens is that certain polygons disappear when you stand in a particular place in the map, facing a particular direction. Almost like an error in the visdata except that it happens without the help of vis.

So if you are going to use it on a map you plan to release, make sure you are pretty thorough in checking it before you put it out the door. I'll let you know if I come up with a fix...