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Mental Ray material problems


Robin3D
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Howdy.

 

I made a scene, lit by only daylight system, all in mental ray.

I've been having some problems with some Arch & Design materials. It's just a simple material with a black image for a table. It has no reflection or whatsoever. It just keeps turning out gray when I render it. Maybe because of the sunlight coming in, but it should affect other dark/black materials, which it doesn't. When I turn the diffuse level all the way to 0, it turns out black, but you can't see the mapping.

 

Any way to fix this without having to mess with my final gather/exposure settings?

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Matt is right it has to do with gamma settings. There is a bit to learn about this but I got some great help from the MRmaterial site I think it is Jeff Patton who explains this very well.

Do you have a link to the website? I never worked with gamma settings before, so it could be the problem.

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You'll find all you need to know on this website http://www.mrmaterials.com/jeffs-blog/75-washed-out-bitmaps-with-logarithmic-exposure-control.html

 

It is worth registering it is an excellent site and load of downloads. There is also a great section on gamma attached when you download a test scene.

He's using the Logarithmic exposure control, while i'm using Photometric exposure control. Is it that important or can I keep using Photometric (without having to adjust it)?

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You'll find all you need to know on this website http://www.mrmaterials.com/jeffs-blog/75-washed-out-bitmaps-with-logarithmic-exposure-control.html

 

It is worth registering it is an excellent site and load of downloads. There is also a great section on gamma attached when you download a test scene.

 

Thank you for the kind words! ;)

 

He's using the Logarithmic exposure control, while i'm using Photometric exposure control. Is it that important or can I keep using Photometric (without having to adjust it)?

 

The gamma is a decision you need to make with Logarithmic or Photometric, the blog and our MatLab settings represent what was available at the time.

 

http://www.mrmaterials.com/jeffs-blog/86-quick-note-on-gamma-issue-dark-textures.html

 

You just need to decide which method you are going to use, we prefer setting the system settings (Gamma/LUT) to adjust images using system settings which is automatically so to speak, and only having to worry about setting the gamma override to 1.0 for floating point/32 bit images like HDRI's and EXRs for example and if you want bump map, displacement, specular maps, etc.

 

It is up to you, the landscape of CG changes with each software release, I think you will notice that Jeff likes using the 'Gamma and Gain' shader now that it is available, this doesn't necessarily change the fundamental system settings, just how you tweak things. Point being, things change so much, I would keep it simple and figure the workflow you want to use and get things working right and then go from there, changing one thing at a time so that you know what did what.

 

P.S. I just created corresponding forum threads at 3DA for each Blog of Jeff's so that people can ask questions while being able to link images and scenes that show their questions. Not trying to detract from this great forum, I am just saying that if you have a SPECIFIC question for Jeff from a Blog we will try to answer it.

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