No artifacts, all goes perfectly, and no more breaking your nerves. So, here is some tips what you need to do to easily create Stencil Shadow for RS. All what you need (except 3D Canvas) is the SketchUp Pro 7, and his *.3ds importer and exporter. You can use it completely free of charge through 8 hours. I think, this would be enough for what you need.
So, export your 3D model from 3D Canvas as *.3ds file. The best way is that making the shadow model in parts. Take one part. Delete all lines that you see except the edges. If there open shapes, there must be closed. See the pictures under.
Highlight the entire model and with the purge option, (Window => Model info => Statistics => Purge Unused) purge all possible components and materials.
Now, you must export that as *.3ds file. Settings must be exactly as shown below.
Now, import *.3ds file into 3D Canvas and continue with rules which define Stencil shadow. About this, the best to read Kevin & Richard tutorial.
Note: You may not have a face with 3 edges! Then you'll get that part of shadow which extends to infinite. Best to add a little edge as shown. Now, they have 4 edges and it does not affect much the shape of the shadows, but solve the problem that I mentioned.
This cab is really complex but this way that I have described the shadow is without artifacts:
P.S. First of you who came to the positive results on the basis of this that I wrote, shall to write tutorial on clearer English. My English is bad.
Regards
Vlado
