mapped surface just behind a solid default clear glass

[Jean-Paul Paloux_cg]

Hi,
if I place a jpg mapped surface on the same plane than a backface of a solid rectangular clear glass, this mapped surface appear pure black and the scene is long to render...

[joe_b]

mapped surface just behind a solid default clear glass

overlapping geometry is always a problem - they shouldn't be intersecting each other. Try changing your secondary ray bias to something like 0.001 and see if that helps. Or, ideally, make sure those surfaces aren't on the same plane.

[Jean-Paul Paloux_cg]

mapped surface just behind a solid default clear glass

Yep. I know but I wanted for a glass. What about an object "in" a block of glass ? Can we control the color of it very well ?

[joe_b]

mapped surface just behind a solid default clear glass

hmm..I'm not too experienced of a modeler, but I think you'd probably need to cut out a vaccuum for such an object. Like a ship in a bottle wouldn't actually be inside the glass, its just contained by the glass. Maybe a more experianced V-Ray user can give you some better tips, but from my standpoint I know that overlapping geometry is a no-no. Basically when two objects take up the same space the raytracer can't non-arbitrarily pick which object its hitting. Thus you'll get odd artifacts where it may hit one plane at one point, and then the other at another.

[Jean-Paul Paloux_cg]

mapped surface just behind a solid default clear glass

I was talking about rendering casted acrylic with an object in it.

[dalomar_cg]

mapped surface just behind a solid default clear glass

I don't know if you have seen or looked at Wouter's tutorial for rendering a liquid in a glass, but it sounds kind of like what you would like to achieve. Here's the link http://www.aversis.be/extra_tutorial...ass_liquid.htm
Its really key not to have any overlapping surfaces. Either have the mapped plane within the solid, or just slightly behind it. Test both ways an see what gives you the best result. Unless your adding some kind of fog or refraction color the color of the object within the volume should be fine.