Gradual motion blur?

#1

Hello everyone,

I’ve been working on this UH60 chopper landing shot, here’s my most recent comp:

http://www.vimeo.com/3510657

I’m happy with it, excluding the keyframes on the landing hit, still needs tweaked.

But I’m not too impressed with the motion blur on the spinning rotors. When viewed in reality, the rotor blades on a chopper are more translucent near the edges and moreso opaque near the center. I can’t quite figure out how to tweak the blur settings in XSI to replicate this effect.

Are there any known tweaks in the render settings that will allow the blur to come in more gradual?

Currently I have Sampling Contrast set to .200 across the board, and transform, deformation, and shutter are all set to 1 with delay set to 0. Default blur settings.

Any thoughts?

-Bobby

#2

Nice. Just add a gradient shader on each arm or a texture that goes from white to black, then unplug from material and plug that in transparency. Also, it seems you have to increase the “motion steps>transform” in the blur or else the blur looks “linear”.

#3

Thanks for the tips. Using a gradiant as a transparency shader makes perfect sense.

I’m having trouble implementing it, however. Perhaps I’m doing something completely wrong. I’ve selected the polygons for an individual rotor, went to model/material/blinn, then I opened up the render tree, clicked on nodes/mixers/gradient, set the gradient from white to black, then dragged the arrow into the transparency connector of the Blinn.

At render however, nothing is showing changed, just the flat texture color from adding the blinn. Any ideas?

#4

Actually it doesn’t at all. The rotor in real life is opaque so it must be in CG.
I have looked a lot picture of helicopter and they are all opaque. Motion blur make looks like transparent. Tranparency will vary with the angular speed of your rotors

#5

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