Isovist Problem

Hi, i'm trying to use IsoVist, but am having a couple of problems, which I wonder if anyone can help with. 

1. The point which I want to use as my plane intersects with one of the obstacles.  I.e. it is either on a vertices, or on a curve, that defines the obstacle.  This does not seem to work.  Is there any way to do an isovist from such a location?

2. I would actually like to run multiple isovist calculations, from multiple point, inheriting both the plane locations and radius information from the results of a previous calculation.  Is there a way to ensure that, when I import a list of 3 vertices and 3 lengths into the plane and radius inputs, this information will be correctly mapped (i.e. length 1 correspond to point 1) as opposed to running multiple equations from each point?

Any help most appreciated.

Best,

Liam