Motion blur (5)

[moss]

Hi,

We all know that 3d motion blur can only blur in a straight line. How do I blur curved motions such as objects rotating fast? Thanks.

Astro

[fredc]

Not sure if I am understanding your question, but I know this produces blurred motion for rations.

1. Select object for blur.
2. Select Info/Selection/RenderSetup and set motion blur to "Exact."
3. Render with Mentalray with motion blur turned on.

Hope this helps,
Urp

[blank-]

hi
just a suggestion. the mental ray motion blur is tooooooo slow and if u have many objects in the scene then its a killer. why dont u try using the external motion blur utility. type mb in the si prompt window to get the various options. u will first have to render out your scene then blur the images from mb using the information from the same scene. hope this is helpful but it is definitely faster.

redman

[atyss]

The problem with motion blur is that it doesn't blur at all if the object is not moving. If it only rotates without travelling in space, no blur.

Once I had to achieve this effect. I ended up creating a matte for the ojbect and blurring it in post (using the matte as a mask) with 2D motion blur. It wasn't as good as a true motion blur, but for the project it was acceptable.

Hope this helps
Salutations - Cheers
Bernard Lebel

[blank-]

hi

i think the mb utility achieves this effect.

[moss]

Everybody try this: Take a long cylinder, rotate it 360 degrees in 5 frames. Set shutter speed to 1. You'll see that the blur does not curve with it. It will take the current frame and the next frame and draw a straight line between them for the blur. This is the case in all 3D packages. Anyway, I just had to make a propeller so I just used texture mapping. Thanks.

Astro

[juan-sanchez]

I was thinking about suggesting using blured texture, but as you weren't very descriptive thought it was too simple a solution

-You could also go for a nice touch of 'temporal aliasing' as it's a fast rotating wheel, I personally love the old 'Bonanza' cartwheel effect !

[moss]

I used a texture map with an alpha made by rendering a single motion blurred frame of the propeller. It works perfect.

Astro