View Full Version : Motion Blur

05 May 2009, 03:55 AM
Hey Everybody, I have a question for ya'll. :) I have a still scene of an elephant ramming a Corinthian column. The elephant is not moving, it is just posed in that position. There will be a camera move that is more or less in a turntable fashion. I thought it would be a really cool idea if I could get a motion blur on him (to help show he is crashing through the column). I am rendering in Mental Ray and I have never done motion blur, though I understand the basic theory. As I understand it, the object has to be moving so the renderer can see where it was at frame one and then at frame 2 and then it does whatever magic to blur it correctly. I've been looking at the 3d and 2d motion blur and vector as well as in the production shader library with the mip motion blur. Is there anyway to achieve this or fake this effect in Maya so when the camera moves around the elephant, it can see the motion blur from all angles? Thansk for any suggestions, I've been racking my brain for a few hours now, and then I realized maybe one of you will know :D.
Thanks for the help

Jonathan Beals
Modeling, Lighting, Texturing

05 May 2009, 08:58 AM
Sounds like that effect would look really cool.

If I was going to attempt it I might try the following:
Key the elephant movement over 3 frames with your pose in the middle.
Then set the animation to cycle.
Now set your turntable animation to be 3 times as long as you need.
Bake the animation on your turntable to get a keyframe on every 3rd frame, and set the tangents on the keys to step.
Now when you render, just render the pose frame and every 3rd frame after that.

The idea is that the turntable will advance and hold for three frames which sync up with the elephant motion cycle, so that the motion blur that your camera sees is just the elephant in that middle pose frame.

Good luck.
Let us know how you end up doing it.

-- David

05 May 2009, 10:26 AM
Nice idea djx; I might have to try that technique myself :-)

05 May 2009, 08:33 AM
Hey David, I was actually looking at your blog to see if you had anything about motion blur when you responded, how fantastic was that timing? Thank you so much for your input, it worked perfectly. I liked the effect, but I showed it to some friends and they didn't understand why it had motion blur, so I might have to push it towards a much more stylized look(maybe something like the flash comic), or hold if off for another project where it would be more appropriate. Either way, I will use this on something.

Thanks again, David. I love your blog btw, it has helped me out so much (Especially the Mental Ray section and the finalgather hide scripts).

Just out of curiosity, I know you are rather fluent in Mel and MR and was wondering if you had an answer to a mel question. I just posted it here:

Basically, I am having trouble creating the Physical Sun and Sky using miCreateSunSky; unless I create it through the globals, delete it and then run the script again-then it works just fine. I know you are busy, but I figured I would throw it out there for you and anyone else that might mosy onto this page. :)


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05 May 2009, 08:33 AM
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