quick motion blur - not image blur

[JeremyHowdin]

As far as I am aware the main thing that slows down a renderer is "true 3d motion blur" which is usually counter acted by a 2d image motion blur solution which works ok, most of the time for PAL resolution, but not for film as RAM usually runs out. Also it's limited to liner motion blur, thus not supporting radial motion blur.

Renderman has a 2d/3d solution for motion blur which usually doesn't add to render time and still provides an excellent result for film - this is one of it's most power features. I am unsure of the exact technique that is used.

However Renderman can't use the quick motion blur solution for everything. If there's a reflective ball in a room it will work but if that ball is reflected in the walls of the room we move into slow render times.

Can Vray support something similar to this? I think this is very important - in other words "true 3d motion blur" at no extra cost!!

[vlado]

Renderman is fast with motion blur because it doesn't do raytracing for objects that are directly visible by the camera (though it needs raytracing for things like raytraced reflections etc); it just draws the geometry on the screen using a technique similar to the Z-buffer. There are various optimizations and cheats (saving on shading and material calculations, for example) that can be applied to this method to make motion blur faster.

VRay always performs raytracing, that's why it's slower. There isn't much room for optimization in that case. There is no "true 3d motion blur at no extra cost" - any speed gains mean that you cheat somewhere (of course, cheating is not always a bad thing).

Best regards,
Vlado

[evandavies]

motion blur question

Hi Vlado,

In connection with the previous post...

I find that the 3d motion blur of VRay is very good but unfortunately its does add ALOT of render time. Can you tell me what settings might be used to lower the quality and reduce render times.

As a wish would it be possible to set some objects to use simple blur such as image while others could be set to true blur?

Cheers,
Evan

[losbellos]

maybe the objects which go straight can have max mb, the other which moves differently vrays, but I never tried, and since max mb is a kinda post effect it could be that it doesnt work out nice, give it a shot.Maybe it works in your case.