Deformed motion with TemporalDegrain() HQ>0

[fvisagie]

When I use TemporalDegrain() I sometimes get deformed motion. It almost looks like a 3D rotation effect - some foreground objects move faster than some background objects.

For example, using

a = last
a.TemporalDegrain()

on http://www.mediafire.com/file/0lym5r657vplaa7/Wide-angle_lens_blurring_sample.wmv, there's deformed motion between frames 22 and 23. In other places too, but that's a good example.

Reducing degrain or SAD1/2 (by a lot) helps a little, but in either case denoising effectiveness is reduced obviously. The only thing that prevents almost all deformation is setting HQ=0, but that also reduces denoising.

Is TemporalDegrain() suitable for clips of widely varying sharpness like this one? If so, what are the recommended settings to use with HQ>0 but without deformation?

Is there another MC temporal denoiser that's more suited to this kind of footage perhaps?

Many thanks,
Francois

[poisondeathray]

Any type of temporal filtering can have this sort of artifact if the motion vectors are not calculated correctly . The motion in the original in this sequence is a slight stutter and I think it's confusing the temporal degrain motion vectors

MCTD didn't have an issue on this sample . It's basically a mega function with dozens of included filters, and many parameters to adjust (but there are presets to simply things)
http://avisynth.org/mediawiki/MCTemporalDenoise

[fvisagie]

Any type of temporal filtering can have this sort of artifact if the motion vectors are not calculated correctly.

You're right, of course . When I emulate what TemporalDegrain does up to the first MAnalyse() but follow that with MShow(), and then repeat that with prefiltering disabled, it's clear that many motion vectors of this clip go missing during prefiltering.

One can force TemporalDegrain() to skip prefiltering with

TemporalDegrain (input, denoise=input, HQ=0 )

but it wasn't quite made to work that way and especially its limiting doesn't work as intended anymore. I'm considering using modified parts of TemporalDegrain() in my script.

Thanks for trying this out with MCTemporalDenoise(), I'll definitely check it out.