Problem with displacement maps

[Peter Litwinowicz]

This is something we’ve experienced over the years with AE’s displacement map filter. basically, it has no filtering to prevent aliasing. Note also, that AE’s corner pinning filter also has this aliasing problem.

In fact, we here at RE:Vision Effects often want to distort or displace things without this aliasing… so much so that we included a filter in our RE:Map product ($149.95) that does displacement mapping, but with all the filtering you need to prevent this aliasing. We’ve also included a corner pinning filter that also eliminates this aliasing (along with other bells and whistles). (and RE:Map has a couple of other filters which I will not go into here.. see https://www.revisionfx.com/rmap.htm ).

I see that you posted the displacement map. Can you post the AE project with the displacement map filter applied (with the comp that creates the stripes, or the image with the stripes as a JPEG file)? If you have an AE project with animation of the displacement map, or the displacement amount, even better (because you will see aliasing much more clearly in the animated result..). Once I have that , I’ll make you a sample project that uses the demo version of RE:Map to show you how much better our filter is.

Pete Litwinowicz
https://www.revisionfx.com

[Bausdtown]

Thanks.

Heres the part of the project with the displacementmap:
https://rapidshare.de/files/23567177/displace.aep.html

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[Peter Litwinowicz]

So I posted a project here: https://www.revisionfx.com/tmp/displaceAndREMap.aep.zip . You’ll need to download the RE:Map demo installer (located here: https://www.revisionfx.com/rmapdownloads.htm ).

In the Satz 10 comp, you’ll see there are 4 layers…. two of which are labeled “AE Displacement Map” and “REMap Displacement Map.” The AE Displacement Map’s visibility is turned off. Turn it on to compare our effect with AE’s.

Some things to note: Since you are using a displacement amount of 50, it is advisable to have the project be in 16bpc… you’ll get much more precise displacments whether using our RE:Map or AE’s Displacement Map filter.

Second: we do different things than AE’s filter if the displacement map and image-to-be-displaced are of different sizes. As such, I changed your displacement map to be 1920×1200 (it was originally 1920×1080) so that you could compare the results more directly.

Third: I set RE:Map Displace’s Warp mode to Inverse (the equivalent of AE’s), and set the MaxDisplace (in the Displacement Controls grouping) to 50. Then, because we do our math a bit different than AE, I set the Vector Scale X and Y to -1 so that I could get the same results.

Fourth: in order to turn on anti-aliasing, I set the Antialiasing Sampling to 3×3. This is the key to getting the better result than AE’s Displacement Map filter

Last: we don’t currently offer a wrap-around edge behavior that AE has, so we have a slightly different edge than AE.

Another thing: if you squash the image alot, you would want to set the Mip-Map method to something other than standard (you don’t need it for this project, but you might in the future).

Let me know if you have any other questions,
Pete LItwinowicz
https://www.revisionfx.com