Sunday, September 23, 2012

Lighting in Post with exr image files.

I was up til about 3am last night trying to figure out a specific render element process and I stumbled upon another process. The images below are: A beauty pass, layers in photoshop that explain how I put these images back together, and a render of each light by its self in the scene. So whats going on?

All these images are rendered as exr file formats. These file format store a lot of color data inside them.
They can exceed normal 8-bit color ranges since an exr is a 32bit floating point format. They are all added togther in Photoshop using LinearDodge(Add). Each image has a  exposure color adjustment layer attached to it. Now I can go through and adjust my lights in post separately saving a lot of rendering time. Here is the file if you want to play with it.

After realizing you can do this, it makes me think how I ever worked before. Adjusting my light over and over then rendering and waiting and waiting. It makes me want to go back and re-render all my other work.

I was talking with my friend Erich who works at DreakWorks about this process and he said this is how they do all their lighting. Not with Photoshop though ;) So I was a little happy about figuring this process out. 

-Render each light by its self as an exr.
-Put back together your image in a compositing package by ADDITIVE.
-Apply exposure to each of your light renders.

Hold Alt while your exposure adjustment layer is selected, then click your layer that has your render. This will connect it only to that specific layer. 

The noise in the shadows are due to low light samples.

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