glass roof not throwing shadows...

[davehitt]

Hi everyone --

I am rendering a scene which has a kalwall-type glass pop-up atrium space. I have a truss system holding up the roof element and, when I use a standard material for the glass roof, I get lovely shadowing taking place underneat the trusses from my sun source above. However, when I try to use a Vray material (of the sort I've used for glass numerous times...) I get NO shadows whatsoever. The sun source I use seems to make no difference; I've tried an IES Sun, a Direct Light with overshoot (my usual method for simulating sun) and a big fat Vray plane light shining into the surface. Nothing works except the standard material.

I seldom use standard materials anymore, so this all has been instructive. Interestingly, the vray glass also makes the scene MUCH darker, even if it's refractivity is set all the way to white...

Any ideas?

Thanks,

dave

[Dynedain]

Make sure to check the box in the vray mat titled "Affect shadows" and that the IOR isn't 1.0. Also, make sure you light source is using VRay Shadows.

[Da_elf]

didnt anyone teach you not to throw shadows when you live in a glass house? hehehe

[davehitt]

not really fixed

Well, your idea of checking "affect shadows" did indeed give me shadows BUT, interestingly, the material is now acting like a mirrored surface. In the top of the image, instead of sky, I'm getting a complete reflection of the interior of the space. I'll attach a screenshot... There is no reflectivity specified on the material, as the attached screenshot will show...

Very puzzling...

dave

[Dynedain]

Turn your reflection value up to white (or almost white) and check on "fresnel reflections"

[Da_elf]

A: make sure glass has thickness
B: i notice you have interpolation turned on for no reason
C: turn up the reflections like they said or
D: just get egz glass and use that, it works nicely

[DZL]

looks like you have logorithmic exposure control on, as well - disable that in your environment panel...

[davehitt]

Thanks...

Thanks for all the input. The rendering was due this morning and, since it was a sketchy sort of thing that I was working up in Photoshop, I just used a Std Max material for the skylight. However, it definitely did not have a thickness value, so that might have been the problem. I'm going to revisit the scene and will take everyone's suggestions.

Thanks again,

dave

[sv]

why not keep it simple?
select the glass object - max properties, untick cast shadows.
Then the glass object won't cast shadows, but the truss system will.