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To get started, let's open the Maya scene, motion_blur.ma. 
(Where are the tutorial files?) 

 

Open the scene, motion_blur.ma, in Maya. For this tutorial we have around 2,000 teapots flying through the air. Note that this was accomplished using Maya's Particle Instancing feature, which RenderMan For Maya supports. Now 2,000 teapots is more teapots than anyone really needs, but it will serve well as a little stress test for RenderMan's motion blur.

 

First render the Maya scene without motion blur. Make sure your renderer is set to RenderMan and run your particles up to frame 35 or so, then render. 

Render-> Render Current Frame

You should get an image like the one below:

 

Flying teapots

(Rendering time: 12 seconds)

 

 

Motion blur would be a nice effect to add to these high-velocity teapots. We can add motion blur by opening the Render Globals and selecting the Features tab. Enable motion blur by clicking the appropriate check box (next to Motion Blur). Now Render the Maya scene: 

Render-> Render Current Frame

You should get an image like the one below:

 

Motion blur enabled

(Rendering time: 19 seconds)

  

An important motion blur control is Shutter Angle. Shutter Angle controls how blurry the motion blur is going to be. The default value is "80". A value of "360" means that the shutter will be open the entire frame, creating very blurry motion blur. A value of "1" means that the shutter will be open 1/360 of the frame, and there will be little noticeable blur at all. 

 

For our image, we could use a little more blurring. Increase the Shutter Angle to "180" and render again. 

Render-> Render Current Frame

You should get an image like the one below:

 

Motion blur with a shutter angle of "180"

(Rendering time: 36 seconds)

 

 

Pixel Samples is the most important setting when rendering motion blur, especially the extreme motion blur in this example. In the images above the motion blur is rather “grainy”, which is undesirable. By increasing the Pixel Samples we create smoother motion blur. We can do this by opening the Render Globals and selecting the Quality tab. The Pixel Samples setting defaults to 3x3. Increase the Pixel Samples to 8x8 (which will cause RenderMan to sample each pixel many more times). Now render the scene again: 

Render-> Render Current Frame

You should get an image with much smoother blur:

 

Motion blur with Pixel Samples of "8"

(Rendering time: 46 seconds)

 

RenderMan handles motion blur well, especially for large scenes with lots of fast-moving objects. By increasing the Pixel Samples, higher quality blur can be created, but, to avoid excessive render cycles, Pixel Samples should only be increased as much as is required.  

For more information about configuring motion blur see the Features tab of the Render Globals.
Read more about Pixel Samples in the Quality tab of the Render Globals.

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