CGTalk - Render Pass End Result (Versus Default Pass)

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Ariel

04-10-2003, 04:53 AM

I do mostly modeling and texturing, although I am very familiar with rendering, but passes are a new thing, now that i started using XSI, so please forgive me if this is an old topic.

It seems that when I render passes in XSI (difuse+spec+shadows) I get a totally different image than if I just render everything in one pass. I want my composited layers to be EXACTLY like the default pass, and then I can tweak details like shadow blur and highlight color and intensity, etc.

For example, in my render the shadows have a color that blend seamlessly with the geometry, but when I composit the shadow pass over the difuse pass, the shadows are pitch black and trying to match them to the geometry seems impossible. Another thing is that highlights, when rendered in layers don't look as strong as they do in the default pass.

I know these are things that can be fixed at the compositing stage, but is there a way to get a closer look before I move into the compositing?

I am using Final Gathering in the Difuse pass. Does this affect at all what I should do in my other passes?

wmendez

04-12-2003, 02:53 AM

This is when Partitions and Overrides comes into play, Partitions are part of your render passes which contain your objects and lights. Overrides can be used to control the specular , Diffuse, etc passes.

General use would be to create a new partition in the pass in question then move the object into it and modify the specific parameter with an override.

Hope I did not lose you, Atyss or Jaco can step in to add more.
you can also take a look at the Rendering and Compositing manual for detailed explanation and examples.

Ariel

04-12-2003, 04:47 AM

From what I've been doing already I kinda understand the overrides concept. My trouble is that I have this model, rendered in Final Gather with an Area Light Shadow all in the default pass. I like how it looks in this pass, so then I try to separate it in 3 passes (diffuse, with the HDRI-FG lighting, a highlight pass and a shadow pass). After I have the 3 passes I open up FX or even Photoshop/Afet Effects to test the compositing on a single frame, and What I get is COMPLETELY different from what I had when everything was rendered in just one pass.

For example, the shadows are black, instead of the color they have in that pass, the highlights are weaker and I find it very hard to achieve the look I already had in that singel pass. There must be a way to extract EXACTLY the shadows and highlights that I had in my one pass render.

wmendez

04-14-2003, 01:53 PM

Ariel,

I see what you mean now, I just did a test and got the same results. The image on the on the left is the default pass and the compd rendered passes are on the right (without any color correction). Shadows and some of the colors are indeed slightly off. FYI In my Ambient /Diffuse pass I used an overried to get rid of the shadows.

http://members.rogers.com/lmendez/FXtree.jpg

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