View Full Version : Strange issues with MR and blur
March 18th, 2006, 18:03
I got some strange problems with mr. My scene is quite simple. There is a car which ride on the road, camera goes behind the car. When I use settings "production motion blur" everything is fine. When I use "production rapid motion" car looks like fly few inches above the road. This is really mistake for me. Can someone explain it? I use Maya7 and WinXP.
Check it out:
March 19th, 2006, 06:41
Thats odd. I'd like to investigate that, but in the meantime...
Since you are using FG, is rapid motion (we call it the rasterizer) saving you any time? What is your motivation for using it?
Have you read the Rasterizer Tips page?
Also, take a look at the Motion tips page, and try fast motion blur mode.
I can't stress enough to try using this mode, if you are going to want ray tracing effects. Set time contrast to 0 and try a samples max of 2. That should be approximately the same sample density as the rasterizer's Visibility samples 4 (same as it sets it when defaulted to 0), ie, 16 samples per pixel.
Sometimes you can also have success with small numbers of Time (temporal) samples, in dense sample areas. Try time contrast of 1, .5, .25, which means 1, 2, and 4 temporal samples per spatial sample.
March 19th, 2006, 13:32
hey bart, thanks for answer and links I must spend some time to read those,
Since you are using FG, is rapid motion (we call it the rasterizer) saving you any time?
in this scene it's 5minuts faster per frame then "production mb" with fg
What is your motivation for using it?
it gives smooth and nice mb renders in this scene
I've found in maya doc this:
Rapid scanline rendering does not support the following features:
* Final Gather
* Raytraced shadows and reflections with motion blur"
,and "rapid motion blur" use rapid scanline, so maybe this is it? But.... there is fg in the rendered image the problem is just this "flyin car"
I've found also one more interesting thing, I render with "preview fg tiles" and when fg tiles are visible it looks like everything is ok but at the end it doesn't --> http://www.rafal.stnet.pl/buick3.jpg
March 19th, 2006, 20:18
I do think it is a bad usage of mentalray using it in rasterizer mode
with finalgather enabled and just for motion blur. or at least it does
not make any sense to me. use it without rasterizer. and even better
save the motion vectors and apply 2D motion blur in post.
March 19th, 2006, 23:25
I always thought that the rasterizer algorithm caches/resuses shading samples and hence they are not re-calculated for every visibility sample for a moving motion blurred object.
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