6 Replies Latest reply on Jan 9, 2009 5:54 AM by (CCarroll)

    Compositing buffers from multipass render of 3D project

    Level 1
      Does anyone have a "Cheat Sheet" or advice regarding the stacking order and transfer modes to use for compositing all the different buffers when doing multipass rendering from a 3D software package (Lightwave 9.5 in my case...)?
      What I'm looking for is the best way to achieve the exact same look as you get from the full render to use as a baseline or starting point.
      I can get close, but not quite the same. Would love some advice from someone who does this on a regular basis!

      I use After Effects CS3 if that has any bearing on your response...

      Thanks!
        • 1. Re: Compositing buffers from multipass render of 3D project
          (Steve_Patterson) Level 1
          Are you rendering with "Fader Alpha" (or whatever LW calls it) enabled? I believe it's the equivalent of what's more commonly understood as a "straight alpha" channel. What kind of passes are you rendering? HDR?
          • 2. Re: Compositing buffers from multipass render of 3D project
            Level 1
            I just need some advice on the stacking order and the best transfer modes to use in AE.
            Using most of these buffers:
            RAWrgb
            diff-shade
            ref
            spec-shade
            depth
            lum
            mostly whatever buffers I can render out all in a single pass.

            additionally I may be working with:
            ambient occlusion, Keylight, Fill light and additional shadow passes
            but I believe all that has to be in separate render passes to come out correctly...
            I only expect After Effects advice on this forum, but if you have some LW advice that can help here too, I'm all ears :)
            • 3. Re: Compositing buffers from multipass render of 3D project
              Mylenium Most Valuable Participant
              Check there NewTek pages. There's an older tutorial lingering somewhere explaining the process for a layered PSD saved with the layered PSD saver. I believe it's this file: ftp://ftp.newtek.com/multimedia/movies/w3dw/PSD.mov. If you check Flay.com, you're sure to find even more tutes.

              Mylenium
              • 4. Re: Compositing buffers from multipass render of 3D project
                Level 1
                Yep.
                I have been searching there as well and found the tutorial you mentioned, and lots of other info as well...but I get the feeling that most Lightwavers either do everything in one pass or render the buffers and hand it off to the next guy in the pipeline, so very few of them have actual hands on knowledge of the actual compositing end (beyond dealing with depth maps and alpha channels and such...)
                (I don't mean that as a bad thing, there are some extremely talented folks on that forum and the have helped me a lot!)

                The most detailed tuts I have found on the process, they all seem to be using Fusion instead of After Effects. Admittedly I don't know anything about Fusion (other than I can't afford it!), but I don't believe it works the same way. I believe it has a nodal system rather than layers, and doesn't seem to use transfer modes (at least the way I understand them...)

                I did find a book on the subject, so hopefully that will give me the info I need. In the meantime, if there are any AE gurus out there deal with this sort of workflow, I sure would appreciate a little help!

                Thanks for passing the link my way Mylenium!
                I don't post here very often, but I do search for help here from time to time and you seem to really help a lot of folks here, including me
                :)
                • 5. Re: Compositing buffers from multipass render of 3D project
                  Mylenium Most Valuable Participant
                  Well, I don't use the buffer savers, either. Since LW doesn't correctly normalize the values, it's quite tricky and I find that setting up extra passes with separate scenes works better (when needed). There is some custom buffer saver tools by Dennis Pontonnier for the node system, though, so that may provide a way to use this feature more in the future...

                  Mylenium
                  • 6. Re: Compositing buffers from multipass render of 3D project
                    Level 1
                    I'm hearing about those a good bit too. I'll have to check them out.

                    Thanks