View Full Version : Fusion and motion vectors

03 March 2008, 02:00 AM
This is knob question
I got my motion vectors out of Maya along with the beauty pass
How can I use the motion vectors to add motion blur in fusion


04 April 2008, 09:33 PM
One way is

Since I am not sure how you generated the MV, read the manual about MB from MV though


04 April 2008, 09:01 PM
if you use fusion 5.2 you can use the vectormotionblur-tool

04 April 2008, 12:31 PM

We have a similair problem.

How does the vector motionblur tool work?

With Maya and Mentalray we use the mip_motion_vector node and get an image that has the motion info stored in the RGB channels.

But, how do we use that with the new fusion tool??


04 April 2008, 04:48 PM
Its pretty straight forward, you pipe the RG channels into your vector.x and vector.y channels inside fusion using the channel boolean tool. Or you can connect your motion vector pass directly to the FG of the vector motion blur node and use the R & G channels instead. Remember to use 16bit float or 32bit float for best results when rendering the vector pass.


04 April 2008, 05:48 PM
You can also use the motion vectors that Maya software stores into IFF images. It's more accurate than the reel smart MB workflow.

04 April 2008, 02:52 PM

it will not work correct. we dont know wy....

we render the color path, then the mip_motion_vector path with the red/green result.
at first we saw, that the objects in the mip-path are on other positions, when the motion is fast - is this normal?

then we put it into fusion.
the color path switch into the vector motion blur - input.

then we put the coloured vector path into a new loader and connect it to the boolean tool - background and foreground (but only the background intput semms to work!)
we let the colour Channels default.
we enabled the Extra Channels under Aux Channels and set "to X Vector to Red FG" and "To Y Vector to Green FG"

than we connect the channel boolean Out to vector motion blur "Vectors".
and set the blur scale to 0.03.

but the the result isnt correct - dont know wy!!
the object motion is primarily horizontal but the resulting blur makes hard edges horizintal and vertical blur, instaed of no blur!

can you help?

04 April 2008, 09:35 PM
The workflow I had was to put the render into the motion vector node and choose red and green within the motion vector node, this is with the lm2dmv MR shader.
The node defaults to vX and vY if I remember correctly, which is for a motion vector pass (iff maya software) not motion vector color pass from MR.

Maybe you can post a test scene to see if I can replicate the result?

05 May 2008, 11:53 AM
hi Life,

thanks for your words.

but now, i am absolute confused.
i understand nearly nothing.
perhaps you can help me to understand step by step?

at first experimented with mip_motion_vector.
i find it here, scroll a little bit down, under maya motion you find three example-files.
but the results are not ok in fusion - dont know why....

but you talk about "lm2dmv MR shader".
i search for it, installed it - but its not easy to understand too!
you talk about a MR shader but say later (iff maya software)!

perhaps you can send me a little scene (a flying ball) with a functional setup?

sorry, but I dont know how I can send you a scene or another file...

regards, Jörg

05 May 2008, 02:41 PM
Did you just call me Life?:hmm:


Go to this thread:

This thread is about a UI developed within Maya to combine motion vector data and beauty passes from Maya.
It will show you the steps to output motion vectors from the Maya Software renderer in very simple steps.

With this you can motion blur in post. I wouldn't mess around with the mip_motion_vector until it is (hopefully) fully supported and documented in the next version.

Good luck.

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