reflective items inside transparent items not reflecting

[tedprice]

Hi there,

I'm sorry for what probably seems like a noob question but I've been pulling my hair out over it. If have a glass dome covering a chrome object, the chrome object no longer reflects the environment. I've increased the max depth for refractions and reflections to 10 on my glass material and max reflections to 10 on the chrome material. I've left the vray global options alone, though I tried overriding the global max depth in the globals/materials section to no avail.

I've attached a shot illustrating the problem. Also worth noting is that a simple glass cube darkens the environment behind it. Not sure what to do about that either.

I've also attached the maya file.

Thanks for any advice!

Ted

P.S. I'm using Vray 2.40 and Maya 2014 service pack 2.

[sharktacos]

For the refractive materials do you have "affect shadows" checked with the channels set to "all"? That might fix it.

[tedprice]

Thanks Sharktacos, I do have affect shadows checked with channels set to all.

[sharktacos]

If GI is on, do you have refractive caustics checked?

[tedprice]

I didn't but checking it now doesn't make a difference.

[vlado]

In the Environment section, the Refraction environment is black - set it to the same texture as the other slots and it will be fine.

Best regards,
Vlado

[tedprice]

Thanks Vlado. That definitely works but it's not exactly what I need (at least I don't think it is). It's probably best to explain better why I'm asking.

I've got a car I'm rendering with the intention of comping on a different background. The GI, reflection and refraction use the same HDR image (okay the GI image is smaller and blurred). The background doesn't have a texture. It's just black.

And it looks arguably decent. Except that the refraction map shows up when you're looking through the car windows. I can't easily use the alpha to comp it out because the alpha for the windows isn't completely black (the glass has some color.) And I can't use a multimatte for the windows because I'll lose the interior of the car as well.

I was actually using the same map in the reflection and refraction slots when I ran into the mental brick wall of figuring out to eliminate the background from my refractions. So I got rid of the refraction map and used black instead. It solved my problem for the windows. But then all I saw for my headlights (glass covering chrome) was the reflection.

The test I have above with the glass half domes was my attempt at reproducing the problem without having to send the whole car file .

I'm not a comping expert by any means so I may be missing the right way to take your suggestion and make it work in AE or Nuke. I've attached some shots to hopefully illustrate what I mean.

Ted

[Dariusz Makowski (Dadal)]

make a black plane behind windows, make it only visible to refraction and set it to blac. Disable visibility to camera. Also disable any recieve shadows,light,cast shad,refl,etc etc. Dont make it too big u dont want to affect headlights.

U should render interior separably btw.

[tedprice]

Thanks Dadal. That works. Sort of. In the shape node for the plane I'm unchecking everything except "visible in refractions". I've created a standard Vray material with a black diffuse.

Unless I'm missing something I now have to do an additional render pass for the alpha without the black plane included because the black plane is picked up by the alpha. Plus I get a lot less light in the interior which seems to be creating more noise (and yes, I should probably render the interior separately). I've attached the alpha and new refract pass.

I feel like there must be an easier way to do this that gives better results.

Is this how people normally deal with windows when they render out cars that have to be comped?

Ted

[vlado]

I guess people just use a textured dome light set to "invisible" - it does not appear in refractions and the background, but it still affects the lighting and reflections.

Best regards,
Vlado

[tedprice]

Doh. That worked great Vlado. Thank you!

Ted

[vlado]

No problem

Best regards,
Vlado