View Full Version : can't render gray...

10 October 2009, 02:36 PM

I feel like this is pretty lame question to ask but I can't seem to find an answer so here it goes:

I'm working on a scene with bunch of concrete blocks in it. They are supposed to be pretty much gray. I made a gray concrete texture, hooked it up to mia_architecture material. Also made bunch of maps (reflection, gloss, roughness) as it is supposed to be polished concrete in a way. I use physical sun/sky and FG to lit it. The problem is that the concrete color turnes out after rendering anything but gray regardless the texture color...

I tried everything: I removed all reflections, I played with diffuse weight, I removed physical sky and used HDRI map instead - the concrete block ALWAYS comes off as light's color (lit part) or HDRI/sky color (shaded parts). I know it is supposed to take light's color but I didn't realize to this extend. The question is, how to I make it appear gray as concrete do? :)


10 October 2009, 02:45 PM
Probably the saturation from the physical sun/sky is contributing to the issues you're running into. Bring up the sky's attributes and turn the saturation down to 0.

The other part that is probably affecting it is the lens shader that is applied to the camera when you create physical sun/sky. If you go to the utilities tab in the hypershade you should see a mia_exposure node. Double-click on that and adjust the gamma value as you see fit. Bringing it down to 1 will give you something closer to what a "default" render will look like. The setting of 2.2 will raise your mid values up quite a bit and can cause some areas to become washed out.

10 October 2009, 07:36 AM
Thanks a lot. After playing a lot with the lens, gamma, saturation of sun and sky I did manage to turn the color bleeding by fair amount but still it's not even close to be as gray as I believe it should be. I think it's basically FG causing color bleeding.

Is there any way of bringing down saturation of FG rays?

There is that nice solution for bounced photons where you can just plug Photon Shader in to the material that causes too much color bleed (I actually never tried it in Maya, know it from XSI) and bring it's saturation down. Is there something similar for FG?

Thanks again!

10 October 2009, 11:36 AM
Well, the sun is going to be emiting blue light, which will bounce off what ever colored object you have in your scene, and land on the concrete. So, it'll never be totaly grey. If you have to have it grey, just do an id pass and de-saturate it in comp.

10 October 2009, 12:03 PM
whitebalance your camera.

10 October 2009, 03:11 PM
Yeah, it all makes perfect sense and I know it should appear as it does but still was just wondering if it was possible to desaturate FG rays. As for solution for this particular problem I'll just go for post-production.


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10 October 2009, 03:11 PM
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