View Full Version : Motion Vectors in Maya 8.5

06 June 2007, 08:01 PM
How can we take out a motion vector pass in Maya 8.5 ? .

06 June 2007, 01:26 AM
You can render out motion vectors in maya several ways.

With the maya renderer, you can use 2d motion blur and check the "keep motion vectors" checkbox which will store the motion vectors in the .iff file. You can later apply them to your images with the blur2d.exe This is useful because you can render motion blur on complex scenes with only a lambert applied to speed up the rendering.

In mental ray you can use the lm2dmv ( shader to output a 8-bit or 16-bit color image with the motion vectors stored in the color channels. This can be used with the reelsmart motion blur plugin for AE or Smoothkit. I'm sure there are ways to use the vector info with shake, fusion or whatever compositing app you use. You need to set the motion blur to "Full" and set the shutter open and close to 0.5 so the blur is not applied to the image itself.

I have read that you can use the 32-bit Motion framebuffer in Mentay ray to render the vectors to color channels without the use of an additional shader, but I have not tried this.

06 June 2007, 07:22 AM
u can use turtle it has a integrated motion vector shader man

06 June 2007, 07:36 AM
Here is other shader and tutorial for post process 2d motion blur in Nuke:
"2D motion blur with p_motion_to_rgb" - tutorial section

I suppose it's not possible to get motion vectors in appropriate fromat without some shader. Because mental ray compute motion vectors in internal format, that usually is not usable for compositing software and we need convert vectors to appropriate fromat.

06 June 2007, 08:07 AM

Your shaders are awesome. Any chance of seeing a version for Maya 8.5 on Mac osx soon ?



06 June 2007, 01:55 PM
to use the framebuffer

in the camera AE > Mental Ray > Out Put pass
create > then choose the pass of your choice
you will have to do batch render , you wont be able to do interactively

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