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RSMB for stereo

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jin choung
RSMB for stereo
on Jan 28, 2010 at 8:48:42 pm

hi,

my studio is currently using RSMB motion blur to generate motion blur on our cg elements for a feature.

the results are truly beautiful and remarkably fast and i can't say enough good things about your product.

but the problem we're having is a novel one and i would imagine pretty new - our movie is in stereo and therefore we're applying RSMB to left and right eye images.

problem is that frequently, there are slight discrepancies between the blur solution in one eye and the blur solution in the other.

this causes an unpleasant buzzing sensation when watching it in stereo and it is a visual artifact we would like to avoid.

have you guys run into this issue before and is there an established workflow in dealing with it?

----------------------------------------

we've been trying to brainstorm ideas and it seems like maybe the best solution is to instead of relying on RSMB to generate the motion vectors, we should generate them out of maya - the assumption here is that maya would not be using optical flow to guess where a pixel went but it knows exactly which pixel went where. is this correct? i've been trying to find information about how motion vector files are generated in 3d apps and the answers i've found suggest that ever pixel is turned into a quad and that entity is tracked for several frames to generate a vector.

another thought we had was to export out the vectors GENERATED by RSMB and try to do a "COLOR CORRECTION" pass to match the vector files. but currently we can see no method of exporting out the generated vectors FROM RSMB.

is there a way? i see that twixtor allows you to generate such vector files but i see no such function in rsmb.

thanks much and if you guys have any thoughts, i'd love to hear them!

jin


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Pierre Jasmin
Re: RSMB for stereo
on Jan 28, 2010 at 10:44:52 pm


For How to Extract Motion Vectors out of Maya (assuming your sources are CG):

http://www.revisionfx.com/support/faqs/motion_vector_FAQs/motion_vectors/#M...

Tell me how that goes and send me some sample stereo files if you want at techsupport at revisionfx dot com

Pierre
RE:Vision Effects



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jin choung
Re: RSMB for stereo
on Jan 28, 2010 at 10:47:29 pm

hi pierre!

thanks so much for the response.

actually, the issue is not getting motion vectors out of maya.

we know how to do that.

the issue is that we DID NOT use maya motion vectors.

so we're using RSMB to generate the motion blur by doing its pixel analysis magic.

what we would like to know is if there is a way to get RSMB to OUTPUT the vector file it generates INTERNALLY so that we can try to do a left eye right eye COLOR CORRECTION on those vectors....

and then, we would feed that BACK into the RSMB motion vector input.

does that make sense?

jin


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Pierre Jasmin
Re: RSMB for stereo
on Jan 28, 2010 at 11:02:07 pm


You need to use Twixtor PRO to generate Motion Vectors.
These Motion Vectors can be piped in RSMB Vectors.
You just have to make sure Max Displace is the same.

Assuming it's parallel view axis you can try:

1) just offseting the MV of one view to the other (a straight translate of the MV image - then some pixels would be missing on one side if you have no padding)

http://revisionfx.com/support/faqs/motion_vector_FAQs/motion_vector_math/


2) If you are in app that supports RE:Map Displace you can try to warp the MV to the other frame using a Motion Vectors Create (in Twixtor) oflow between views

Of course both of these techniques will probably fall apart if there is a lot of parallax between views


There is probably a more convoluted workflow I could come up with but I would need some sample frames


Pierre




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jin choung
Re: RSMB for stereo
on Jan 28, 2010 at 11:09:20 pm

thank you again, pierre.

we will look into twixtor and see if that workflow will fit into our schedule.

yes, we are using parallel cameras (no toe in) and our left eye is almost done being rendered completely.

i think that if we render out motion vectors out of maya, we may solve our problem because i think then the motion vectors will have been arrived at without guessing (i.e. without pixel analysis)... i THINK.

but we want to avoid having to re-render anything in maya.

ok. thank you so much and i might be back with test footage....

:)

jin


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