Black arc appearing in glass

[rhino]

ok elfi, have fun with no alphas. The egz glass got non.

And rhino, for what do you need an IOR that is different from a plane. Why wasting Polys. My window-glass has 1 poly for 100 windows, your tec. means that you have 600 Polys for 100 windows. Would not work for me, scenes i build for clients have at least 1,5 Mio Polys.

greetz

Because real glass is a solid mass, well it's actually considered a liquid if my high school science class was correct and it has an IOR, bad computer renderings have single sided planes with tons of reflection and no refraction. joking, no seriously I remember when I would wait 3 days for an image to render just so I could have refracting glass, now it's a standard effect. If you are really worried about faces just make the one large plane into a box, I'm sure Vray can handle the extra 5 faces, splurge a little, so that's one less rpc object you can put in the scene, well would that be so bad? hell if I put enough windows in my scene I could totally do away with RPC objects, then I would be living in some sort of arch viz utopia.
Personal preference aside, there are some valid reasons for not using single sided objects, in my experience they cause havoc in a raytrace environment, this was certainly the case with FR and I have experienced similar anomalies with Vray (GI problems, artifacts, crashes) I consider it good practice to do away with bad faces/open objects. Vray is certainly robust enough to render refraction in glass, the speed tradeoff is minor, working with refraction just takes a bit of preparation and planning but is worth the extra effort for the resulting quality. It's up to you if you want to use refraction but I certainly suggest using two sided objects to avoid problems and insure max compatibility with other and future raytrace engines.

[egz]

ok elfi, have fun with no alphas. The egz glass got non.

Uhm.. yes it does.