Vray Velocity Pass and Revision Twixtor for AE not working together?

[Robert1977]

Hi all,

does anyone know how the VrayVelocity Renderpass can be used for Time Remap inside Twixtor? I tried it with the red channel for x and the green channel for y movement, but it seems that the amount of movement is not the same when I generate the motion vectors from withing twixtor and compare them to vrayvelocity. Twixtor doesnt create a pixelmotion inbetween frame with vrayvelocity, but a frame blended one, as if it cannot interprete the color information correctly. File format is hdr.
Does Twixtor anyhow blur its movement channel?

Best regards

Robert

[king_max]

Why would you want to time remap the velocity pass in the first place? Why don't you use Twixtor on the final composite instead?

[Robert1977]

Hi king_max, thanks for your reply. I use twixtor on the final composite, but I would like to improve its twixtored output quality by feeding in motion vectors created by vray. (Twixtor Pro Vectors in), because I believe this would allow me to get rid of the artifacts that occur on details (handrails, curtains with thin lines). And now I see that the vectors don't fit really.
Sorry for the misunderstanding, probably my explanation. I don't want to time remap the velocity pass, but to retime (time remap) the final composite with twixtor with the aid of vray velocity passes.

Cheers Robert

[king_max]

I'm not really sure the Twixtor Vectors are supposed to work with the velocity pass. Why don't you ask directly on the Revisionfx forums?

[Robert1977]

Yes, I can do this in addition. Also, maybe Genarts Speedo or TheFoundry Kronos produce better results.

[tammo]

Did anyone get this to work?
I also tried to use the vray velocity pass with twixtor and the resulting frames looks wrong even if you flip the x and y directions.

It would be awesome if we could get it to work with vray.
We would only have to render half the frames of animations with slow camera moves,
like architectural walktroughs.

But without the velocity pass the quality is not good enough.

[Robert1977]

Hey, unfortunately not. I wrote to the creativecow-forums and Pierre Jasmin answered and gave me some hints. So I tried out a few things, but in the end it didn't work yet:
-VrayVelocity is movement from current frame to next frame
-Max Standard Velocity Render Element is movement from previous to current frame
-So you could probably use both in twixtor pro vectors in, since there are both vector channels (previous, next)
-Tried out 8bit PNG, 16bit TIF or 32bit HDR images as velocity channel, but didn't get a convincing result
-Used max velocity as variable in twixtor, but didn't work correctly
- Vector scale x and y is probably the max velocity in the movement divided by the width or height of the velocity images?
-You have to keep in mind gamma correction, rgb color space etc for the velocity images, but I didn't find a real solution.
-A movement of 0.5 is no movement, but weirdly the created motion images have a saved value of 0.4998 or 0.5002 by 3DSMax or Vray.
-Maybe Chaosgroup can give some tipps? As far as I know most use the velocity channel for motion blur, but as you, tammo, i would like to use it for artifact free inbetween frames
-My purpose was to create 50frames out of 25frames for Bluray HD Ready format 1280 x 720 frames by 50 frames progressive per second. Side effect is that quick movements in 3d get really smooth without shutter effect. But never really tried motion blur, sometimes not wanted in architectural visualisation.

Cheers

Robert