Different settings for different render layers?

Hello. I’m a bit new to blender and was wondering how to do a few things with render layers and the node editor. Is it possible to have different settings for attributes per render layer? For instance, if I want to have raytraced ambient occlusion on one layer and approximate indirect lighting on another layer and composite them together in the node editor, will I be able to set different gather modes for different layers? I’ve also used Maya, and there is an option in Maya to set layer overrides for pretty much everything and I was wondering if Blender has something similar. Thanks.

If I were doing something like that, I would immediately and voluntarily plan to do this using separate Blender runs … generating individual “MultiLayer”-format output files from each one. (You can set up the master blend-file, then start linking to it from others.)

My main motivation is that, once I have done one thing successfully (especially if that’s a time-consuming “thing”), I don’t have to re-do it. I can check that one off my to-do list and focus exclusively on the next time-consuming thing. Once all of the inputs are finished, I move on to the next step of compositing them together … and so on.

Also, I would delay those time-consuming operations until the last minute. Especially if you’re doing an animation, I’d do “preview renders” (with the 3D window button) until I had everything just the way I wanted it, and only then begin to replace the files one-by-one with their “actual” equivalents … rendering only and exactly those frames that I have determined that I need.

I’m having a bit of a hard time understanding what you said being new to blender and all so I apologize if I got this wrong. From what I understand, you’re suggesting that I have different blend files for the different set ups that use a master file, render out the passes or layers that I need and then compositing them together, yes? If so I’ve considered this option, but I wanted to see how much I could simplify the compositing process. Ideally, I want to have all the passes assembled and all the effects in place before rendering out the image sequences and do only minor color corrections on the rendered images afterward. Being able to have different settings for different layers in a single file would be really helpful in doing that since I seemingly can’t use both approximate and raytrace gather methods for different effects in a single render or have different attenuation values for AO and indirect lighting, so I just wanted to ask if it’s possible to assign different settings in separate render layers.

Actually, I am following a tutorial at the moment in BlenderGuru.com, if you want to check it out, you can see the effect it has. It is the “underground railroad” tutorial, and its actually the second section, not the first. You will have to fast forward through it to see what he does with it, but it has some pretty cool effects. I am a total beginner with compositing honestly, this is my second time even using it, but you can do some awesome effects once you figure it out.

do this using separate Blender runs
You don’t really need separate Blender runs. That is what scenes are for. Each scene can have a different world (which is the container for the AO/Indirect Lighting settings). You can cross link objects/meshes into different scenes. So it is possible to have the same object appear in many scenes, in a single BLEND file and each scene can have its own AO or Indirect lighting settings.

You would then use compositing nodes to pick and choose what scenes and Render Layers you want to combine into a final image.