View Full Version : displacement artifacts?

02 February 2005, 08:29 PM
i seem to be getting artifacts from after effect's displacement. it's a pretty standard setup, i'm using a particle pass to displace footage to simulate heat distortion from a spaceship landing.

but i keep getting odd black pixels on the displaced footage layer. the only thing it could be is from the displacement plugin, turn it on they appear, turn it off, they disappear...

has anyone seen anything like this before? any thoughts or suggestions?


02 February 2005, 02:43 PM
I have had some odd hiccups with displacement as well. Out of curiosity, is the layer you are displacing the background (bottom most) layer, or is there another underneath? If you create a colored solid of bright red and put it under the layer you are displacing, do the black artifacs become red?

As I said, I've had odd problems with the dsiplaceing, and have had luck simply placing a copy of the displaced layer under it so if there are breaks of "holes", the background is at least the same and for just a few pixels, is should blend in well.

Hope that helps.

02 February 2005, 05:51 PM
great idea!

still not sure what the issue is but this is a good workaround.


02 February 2005, 07:07 PM
I dunno if this will work but is the edge behaviour on or off? i.e wrap pixels around.....stretch map to fit might help...and check what channels you're using to displace....maybe alpha instead of luminance or vice-versa. Dunno for sure but hope this helps. Take care and all the best.:thumbsup:



02 February 2005, 09:56 PM
well i couldn't 'fix' the problem so what i did was apply a luma key after the displacement, threshold of 1 and put an undistorted version of the plate underneath it. it seems to hold up so i guess that's the solution.

thanks for all the help guys,

02 February 2005, 07:32 PM
Good to hear you got it working. Usually, I don have to key out anything, because they are literally little holes in the composition. Cool work around though. :thumbsup:

Out of curiosity, what were you using for your displacement map, a .tga sequence, uncompressed .avi or .mov, or something with compression on it, and were you using balck and white or color to dsplace?

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