I'm experimenting with the Render Pass script I have.

In what mode are these passes supposed to be composited? I have tried Normal, Add, Multiply, Lightness, etc, but can't get any combination of these to look at all like the image when I render it with one pass.

I have tried keeping it simple with a 3 light setup (I'm still using Poser 6), without a separate pass for Shadows or Occlusion, but my compositing attempts look terrible.

Thanks for any enlightenment.

If you're trying to get the combination of images to look like a one-pass one, then why not just do a one pass render?

You need to explain what you're attempting to achieve.

There's no set rule about how to use the passes. The whole point is that you manipulate them to get the look you want. That may take some experimentation and is definitely something you do on a case by case basis. If the look you want is achievable in one pass, then there is no point in compositing. Compositing is for when the look you want is not achievable via a single render.

You probably want to know how to combine diffuse and specular first, same as Poser is doing in single pass.

Linear Dodge. This is an incredibly unhelpful name for "add".

A shadow or AO layer would be combined via Multiply.

Thanks for your replies.

I'm not trying to exactly match what I can get in one pass. I'm trying to better understand how the lights affect each other, and to learn what effect small changes might make.

I figure if I can render separate passes, and then composite them into something that looks more or less like the one-pass render, then I can more easily and quickly experiment with the render layers instead of re-rendering with the lights.   A little more of this light, a little less of that shadow... that kind of thing.

This is the kind of thing I was looking for:

You probably want to know how to combine diffuse and specular first, same as Poser is doing in single pass.

Linear Dodge. This is an incredibly unhelpful name for "add".

A shadow or AO layer would be combined via Multiply.

Thanks folks!