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Activity Forums Adobe After Effects 3d+shadows+motion blur = moire pattern

  • 3d+shadows+motion blur = moire pattern

    Posted by Ian Tomey on May 27, 2009 at 9:50 am

    Hi everybody

    I’m having a problem with… something. most of the time my comp is fine but i’m having problems on certain frames generating moire patterns. see examples Here

    the layers are 3d, have motion blur and cast/accept shadows turned on. as you can see i’ve played with the shadow map size to no avail. also trying changing shutter angle and number of sub samples. the only thing that makes the render smoothly is by turning motion blur off – which i don’t want to do. (and yeah shadows are needed as there is other stuff in the scene i’ve turned off)

    *edit* started soloing the layers and that has isolated the problem. the segments are all on the same plane (i.e. z is the same). I’ve seen this before when things have overlapped on the same plane, but these aren’t overlapping.

    open gl is off, comp is HDV 1080 25. I’ve tried turning multiprocessing off to no avail.

    any ideas, because I am out of them!

    Ian

    Brian Charles replied 16 years, 11 months ago 4 Members · 7 Replies
  • 7 Replies
  • Bill Kelly

    May 27, 2009 at 11:25 am

    Two different things I can think of to try, no guarantee either will work though.

    1. If your project is 8 bit, try switching it to 16 bit.

    2. Transcode your footage to something other that HDV and reimport it.

  • Joe Laude

    May 27, 2009 at 12:26 pm

    Just out of curiosity, are you looking at your comp at Full resolution or Half? I noticed on a composition a few months back that when I had video that had a pulldown that I had removed, it would still show interlacing artifacts if I RAM previewed at anything lower than Full resolution, though that wouldn’t explain vertical interlacing lines.

    If it is being caused by your 3D layers being coplanar, you might try offsetting the layers by something tiny like 0.01. The offset would be negligible, but they wouldn’t be coplanar anymore, and it might solve your problem.

  • Ian Tomey

    May 27, 2009 at 12:28 pm

    Thanks, I’ve tried 8/16/32 forgot to mention that

    I’m not sure what you meant by transcoding the footage – they are just shape layers. and even reducing the resolution by 50% actually makes the problem worse.

    I’m wondering if its a shape layer issue as they seem to be treated like a solid with a mask applied – perhaps the 3d engine is calculating the full size of the “solid” and getting confused. Like I said i’ve had the same kind of trouble with overlapping footage on the same z plane before.

    hopefully later on today i’ll try something with nested comps instead of shape layers – i cant just precompose everything because all the attributes go in the child comp and it throws everything off.

    Ian

  • Ian Tomey

    May 27, 2009 at 12:33 pm

    Those samples are at full resolution, at 50% its even worse!

    yep i tried nudging the z’s and it did work, the only trouble is due to the angle that they are in and the angle of the light shadow, they then looked out of line with each other (4 outer slices in that image)

    i’m going to try with nested comps with the shape layers in – i did one as a test and it worked out fine, though was impossible to precomp them all properly. it only allowed me to put everthing in the child comp, (because the layer “has no source”?) not the parent, which broke all the parenting and would require the whole thing being redone.

  • Bill Kelly

    May 27, 2009 at 1:23 pm

    By transcoding I mean changing your footage to a different codec than HDV. AE and HDV don’t get along really well. Export your HDV footage as Apple Pro Res if you’re on a Mac with Final Cut Pro, or try the Animation codec if you’re on Windows.

  • Bill Kelly

    May 27, 2009 at 1:34 pm

    Whoops never mind, I just reread and saw you said everything is shape layers. My bad 🙁

  • Brian Charles

    May 27, 2009 at 2:06 pm

    Could the pattern be due to the number of samples per frame setting for motion blur? Increasing or decreasing the number of samples may help or adjusting the shutter angle.

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