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View Full Version : Tone mapping in Renderman


Wolfganng
07-20-2009, 09:42 PM
Ive recently Ive gotten into Renderman for Maya and I was wondering if anyone knew how to apply tone mapping to your output image in the render view, similar to how the photographic exposure in mental ray works. Thanks in advance.

leif3d
07-21-2009, 01:32 AM
You have to write your own lens shader.

For simple Gain and Gamma control look into the "exposure" control in the "passes" tab in your render settings.

These are the settings I use to work in a Linear workflow (besides gamma correcting swatches and textures). I then Tonemap in Fusion.

Wolfganng
07-21-2009, 02:03 PM
Thanks Leif. So to have a correct preview with a linear workflow I would gamma correct swatches and textures, and use a 2.2 gamma in that Gamma control in the exposure settings?
Also, any guidance into how to implement my own lens shader? I remember reading somewhere in the documentation that Imager Shaders could be used for applying such things. I found an implementation for a tone mapper in a technical paper, but have no idea to apply that code on RFM. Anyways, Im still learning so any help is appreciated. :)

leif3d
07-21-2009, 04:10 PM
Thanks Leif. So to have a correct preview with a linear workflow I would gamma correct swatches and textures, and use a 2.2 gamma in that Gamma control in the exposure settings?

Yep. Pretty much. You will also need to gamma correct lights. Also, the filetexture node has a Renderman attribute that has a "apply sRGB" aka gamma correction, so no gamma node is needed.
Remember, Gamma correction should only go into gray values and colors, not Black or white. (0 or 1)


Also, any guidance into how to implement my own lens shader? I remember reading somewhere in the documentation that Imager Shaders could be used for applying such things. I found an implementation for a tone mapper in a technical paper, but have no idea to apply that code on RFM. Anyways, Im still learning so any help is appreciated. :)

I'm not a programmer myself, so I have no idea how to implement something like this. This would be a good question to ask in the Pixar forums, where you'll get responses from Pixar TD's.

beaker
07-22-2009, 05:27 AM
wouldn't it be way faster to do tone mapping a 32 bit float image in a compositor or other 2d app rather then the very expensive process of rerendering a tone mapped image till you get the right look?

leif3d
07-22-2009, 06:54 AM
wouldn't it be way faster to do tone mapping a 32 bit float image in a compositor or other 2d app rather then the very expensive process of rerendering a tone mapped image till you get the right look?

Yep, completely agree.
I tonemap in Fusion, but any other compositing package will do a great job.

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