hi Sequana,
For me just using offset 0,5 did the trick - it was few months ago and I don't remember details - if you still have problems I can look for files in my archiv to see exact parameters I set.
In meantime I'm sending you what RE:Vision Effects Support sent me (nothing special but may help):
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My question:Does it support Velocity channels created with CoronaRenderer - as you can see here [example how to make it work with Fusion -
] or I can attach any example file if you want and send me your email. The velocity channel is way different and I completely can't get it work with RSMB Vector as it was with Vray.
Their answer:Probably, but we have no experience with this. I see that they put the motion vectors into the velocity x and velocity y channels of an EXR file. You'll see in the Fusion tutorial that they convert this to red and green channels (which is also what RSMB needs). However, you will need to do more than that, because we expect our motion vectors to be transformed to red and green channels in a way that is not just copying dx and dy to red and green channels (you can read about our motion vector format at this link:
http://revisionfx.com/faq/motion_vector/ )
Basically, in a floating point image handed to us with dx in the red channel and dy in the green channel, we make the motion vectors using this math:
Vector x for RSMB = (red *2.0 –1)*MaxDIsplace;
Vector y for RSMB = (green* 2.0 –1)* MaxDisplace;
So you'll want to make your motion vector images:
Red = ((CoronaRenderVectorX)/MaxDisplace + 1)*0.5;
Green = ((CoronaRenderVectorY/MaxDisplace + 1)*0.5;
Where MaxDisplace is the value used to scale the motion vectors as described in the FAQ link I listed above. If you are using floating point images and a floating point project in AE, then you can set Max Displace to 1.0.
So in this case where you use MaxDisplace to 1.0 (using floating point EXR and floating point AE project), then in the Corona Renderer velocity settings, I believe you should set
Multiplier to 1.0
Offset to 0.5
Then you'll need to import the EXR sequence in After Effects. Make sure to right-click on the footage in the project bin, select "Intepret Footage.." and under the color management tab select "Preserve RGB."
Then drop your vector footage into a comp. Apply the effect Effects->3D->extractor and select the X velocity to go to the red channel, and the Y velocity to go to the green channel (and copy the alpha channel)
Then put this vector comp (it needs to be pre-comped!) and your color elements (which may be in the same EXR footage) into a comp together and apply RSMB Vectors. Set RSMB Vector's MaxDisplace set to 1.0. Depending on how Corona renders, you may need to flip the Y vector by setting RSMB Vector's Vector Scale Y setting to –1.
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I hope it helps.
Regards
PEgaz
