Multipass Workflow in C4D

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  04 April 2013
Multipass Workflow in C4D


I am wondering how you guys are working with the multipasses in C4D because I have problems recreating the beauty pass.

I combine them like this:

Diffuse+Spec*Shadow+Ambient+GI*AO+Reflection+Refra ction.

I have problems with hair in Combination with Physical Renderer, which doesn't show up in the passes but it's a limitation discribed in the help and a problem with the Atmosphere from Physical Sky. If I multiply/add both of the atmosphere passes, it still doesn't look like the beauty.



Would like to hear some of your ideas and workflows.
  05 May 2013
Sorry for the double post but I am wondering why there is not a single reply but over 150 views.

Is there no solution to this problem or is the solution so obvious, that no one wants to reply.
I can't imagine that there are no people with serious multi pass experience with Physical Renderer and C4D.

Just wondering if I should scrap a real multipass workflow for my bachelor thesis and work with the beauty + additional masks, depth and point world passes or go with a full multi pass workflow.
  05 May 2013
Wish I could help, but really have not done much anything at all with Multipass. Hopefully someone can help you out. Good Luck.
  05 May 2013
Can you post a link to the EXR-file?
  05 May 2013
Thanks for the replies guys

After some consideration I decided to upload the EXR I used above. Maybe it is easier to help, if you have a file to play with.

Sorry for the heavy exr but it was rendered for internal tests and contains almost all availible passes. Would have kicked them out later, when I figured out a workling MP solution.
  05 May 2013
At the risk of stating the obvious, did you make sure to have your comps in 16 or 32bits and linear workflow set right (preserve RGB on maybe)?
  05 May 2013
I checked the LWF just to be sure. Seems to be fine.
  05 May 2013
there is a Nuke set up image here

mism was kind enough to post..

But i have had issues with grass as hair objects in post..

  05 May 2013
My multipass setup is only for VRay I'm afraid. Its been ages since I've used Cinema's renderer, never done any complex comp with its hair or physical renderer.
  05 May 2013
Sorry for the late reply, was busy with the project.

Unfortunately mism's thread is about vray, which I don't have at the university but it was the starting point of my efforts. I even commented in his thread about my intention to do multi pass compositing in c4d but this effort could be in vain, since I can't even recreate the beauty with the passes... and judging from the comments there aren't many people using a full multi pass workflow with cinema's renderer...
  05 May 2013
Take this with a pinch of salt as I'm an animator/rigger, not a rendering guy, but multipass/compositing always feels like a black art to me in Cinema. Even something really simple like rendering out an image with a transparent background and having that show up in Photoshop stumps me here.

Attached is what I get in Photoshop if I render a simple cube out of Mental Ray and Cinema with Alpha enabled in both cases. Why is the background in the C4D version black? If I look in the PS channels tab I can see there's an alpha channel there but why is it necessary to then use that as a mask to cut out? Is there not a simple way to just render out a transparent background like the MR version? I've tried the Alpha, and Straight Alpha options but neither seem to work for this.

If I'm just making a noob mistake I'm all ears and keen to know how to fix this. Seems it should be more straightforward though. In Mental Ray it's simple to do and it works for all passes too which makes things simple to work with in PS or AE. In Cinema I've never managed to get that working either, the passes just seem to be RGB no matter what I do, but I want RGBA ideally.

  05 May 2013
I've noticed that same thing with C4D alphas and have been wondering if that was proper behavior. I end up having to render a separate alpha and then setting a track matte in AE...
  05 May 2013
Originally Posted by gdogfunk: I end up having to render a separate alpha and then setting a track matte in AE...

Yeah, me too, which 1: means more rendering time (and more HD space for more passes of course) and 2: makes the comps in AE more complex (and therefore slower) than they need to be. Even on a pretty simple scene AE always feels pretty sluggish to me and this kind of thing makes it worse. I was sure I was doing something wrong but could never figure out how to fix it.

  05 May 2013
this is an image straight render with alpha channel in other alpha put in here just the straight render.. and it does have the transparency with it.. I think it is a PS thing..
Attached Images
File Type: jpg trns.jpg (91.5 KB, 9 views)
  05 May 2013
I guess you're right. I notice if I load both of my test images (which were saved out as PS format from C4D/Maya) into AE the background is transparent. I wonder why not in PS though.

That's just the main image though, I'm almost positive that none of the passes out of Cinema can have alpha channels embedded like the ones out of Mental Ray do if you set the frame buffer to one of the 4 channel (RGBA) options.

Maybe the amazing partnership we've heard about with Maxon and Adobe will fix basic stuff like that LOL. I'm still using AE 5.5 though and have no major incentive to upgrade, especially with the new subscription model.

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