View Full Version : MR vectors and F_MotionBlur

07 July 2010, 08:41 PM
Hello all!

I'm trying to figure out a way to use motion vectors rendered out of Mental Ray to drive the FurnaceCore MotionBlur node... Does anyone have any experience with this kind of workflow?


07 July 2010, 05:03 PM
You will probably want to use the standard Nuke Vector Blur, not the furnace node for this. mental ray Motion Vecotors are in a different format to the ones expected by Furnace.

What format mental ray vectors are you exporting ? ie Toxik2dNormalised from Maya or ?

07 July 2010, 05:22 PM
Here's my thought process...

I've gotten decidedly mediocre results from the vectorblur node, possibly through some misunderstanding in how to use it.

On the other hand, I get lovely results using Kronos / F_MotionBlur, but an unacceptable number of artifacts from the optical flow vector calculations.

So, I need to either figure out how to get better results from VectorBlur, or find a way to provide more accurate vectors to the Furnace plugin.

I'm currently rendering out Toxik2D (non-normalized), but my workflow is entirely flexible

07 July 2010, 10:05 AM
this workflow i find that its getting a very good result ...

this image was composited in Nuke...

first .. in maya .. i made motion vector pass with
((puppet shader - motion to RGB shader)) ... it will give
you a perfect effect...

then inside nuke make this tree

plug the MV pass as (input 1) in shuffleCopy thin "forward channel" as U, V channels
and plug the default color stream in (input 2) as (RGBA)

and in the vector blur node ... just select the channel "forward" because in the
shuffle we plugged the motion vector pass as forward ((U, V))..
and begin playing in values to choose the right values to the Mblur

:thumbsup: i hope this could help you

07 July 2010, 10:46 PM
Thanks for that!

I'll definitely give it a shot. A lot of the puppet shaders look useful, I'm surprised I've never heard of them before.

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07 July 2010, 10:46 PM
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