View Full Version : background shader not reflect real texture

07 July 2011, 05:30 PM

I've a problem with background shader.
My scene is really simple..
- sphere at center of the world (with a fully reflecting blinn shader)
- IBL with an HDRI
- base plane with background shader what I see is all OK without the reflection of the base plane that is all black.


How can I fix it?

thanks to everyone that can help me..

[ehm.. apologize my english.. I know that somewhere I have made some horrible grammatical mistakes]

07 July 2011, 08:26 AM
I'm not sure I understand you correctly, but I'm guessing you only want the reflection of the ball in your floor plane, and not the environment map, right?

is it a "use background" shader? in that case, do you have specular color set to white and reflectivity set to 1? you also need to make sure raytracing is turned on in your render settings.

07 July 2011, 12:52 PM
another useful thing that I don't know.. wow.

But, what I mean with my previous message is:

When I render my image I have something like that

As you can see, the base plane with Background shader is reflected completely black.
What I want is only shadow in reflections.. it is possible or I need to mask almost everything and composite in Photoshop?

07 July 2011, 01:14 PM
aah. I see what you mean.
Actually, when you're rendering with mental ray, you shouldn't use the "use background" shader. it's very old and doesn't have the funktionality you need for this kind of stuff.

I suggest you use the mip_matteshadow shader instead, and connect your IBL also to the background slot of that shader.

You also need a exposure lens shader on your camera that will gamma correct your output image to 2.2 gamma. just connect a mia_exposure_simple to the lens shader slot in the mental ray rollout on your camera shape node.

07 July 2011, 04:04 PM
Oh.. I didn't know anything about this shaders.

ahm.. witch attribute I need to connect from IBL to matteshadow.background?

Thanks for your help ^_^

07 July 2011, 05:03 PM
IBL and Dinosaurs have the same age.
Look at this explain tutorial

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07 July 2011, 05:03 PM
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