5 Replies Latest reply on Apr 1, 2011 4:47 AM by dan_hin

    odd artifacts in 32bit comps

    dan_hin Level 1

      Hi all (mainly Todd),

       

      I'm experiencing some odd artifacts when using luma mattes in AE CS5.

       

      If I use a 32bit matte with a 32bit fill, there are some odd "black" artifacts that occur round the fringe of the matte. The AE info panel reports these as having an RGB value of NaN - I've attached an image to demonstrate this:

       

      32bit matte issues.png

      I'm using .exr files from R11 of C4D if this makes any difference..

       

       

       

      Cheers

      Dan

        • 1. Re: odd artifacts in 32bit comps
          Mylenium Most Valuable Participant

          Yes, C4D does not correctly render 32bit Alpha and messes up when embedding it in 32bit formats. Render the Alpha as a separate sequence and use matting techniques. NaN is for "not a number", meaning an invalid value format.

           

          Mylenium

          • 2. Re: odd artifacts in 32bit comps
            Todd_Kopriva Level 8

            Mylenium certainly knows Cinema 4D better than I do.

             

            Lutz, are you saying that this is a bug in Cinema 4D?

             

            Dan, have you seen this issue with mattes generated from other software, or just Cinema 4D?

            • 3. Re: odd artifacts in 32bit comps
              Mylenium Most Valuable Participant

              Thanks for the flowers, but I've only recently started to use that sucker again after years of staying away as best as I could (though even then I helped out some friends occasionally) I'm reasonably sure it is an issue in C4D and they are aware of it. I seem to recall that it was "fixed" in one version, but then broke again when they started reworking the render engine in recent versions. I think they're still treating Alpha as 16bit and that seems to conflict with some settings for antialiasing and sampling. Also using some of their render effects like Vector Motion Blur has been known to show this behavior. It's not occurring per se, but seems to be tied to specific combinations of things. Might wanna advise your peopel to chit-chat at NAB about it (and snatch a test license perhaps for investigating?).

               

              Mylenium

              • 4. Re: odd artifacts in 32bit comps
                Todd_Kopriva Level 8

                I think that the best thing for us to do, then, is to put this in our bug database and then use our usual process for handing off bugs to other software companies. In other words, I'll take it from here.

                • 5. Re: odd artifacts in 32bit comps
                  dan_hin Level 1

                  Thanks Mylenium and Todd for confirming what I already suspected - C4D is buggy as hell, especially  in versions <R12.

                   

                  Can you clarify if you've discovered this behaviour as it applies to 32bit object buffers? There's no "alpha" in the scene; the footage is luma matted with the greyscale object buffer from C4D.

                   

                  Thanks again,

                  Dan