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Rendering points with mblur


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Hi.

I have one problem while rendering points with mblur - time.

5 mln. points without mblur takes 13 sec (8x8 samples, raytrace)

the same points with v == [30,0,0] takes 25 sec

the same points with v set to curlnoise in vops (even barely visible) take 5+ min.

Why direction of the velocity affects so badly rendering time, even more then actual speed? Could someone explain in depth ( i mean a bit of theory)

And how to improve rendering times with chaotic point velocity?

Thanks in advance

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We've just gone through this a lot actually and have uncovered a couple of bugs in mantra when dealing with large amounts of overlapping points. The biggest one being an n2 loop in the code when there's lots of overlap. This may not help you right away since it's been fixed for 12.5 only, but there are a few things you can try now.

1. Try to reduce the pscale of the points in the high density areas to reduce the amount of overlap. This has some limited success in my tests.

2. Reduce the kd-tree memory factor to 0.1. This can sometimes make a significant difference, sometimes not so much ;).

3. Change the geometry measuring in the Dicing tab to Raster Space Measuring. In my early tests this made a bit of a difference, but I haven't gone back to test if it is really that significant.

4. If none of those work then you can try switch your Ray Tracing Acceleration to Bounding Volume Heirarchy.. that also helps in some cases.

Unfortunately I've discovered that not all of these will work in all situations, but it's helpful to know which settings you can play with to make the most difference. Hopefully when 12.5 rolls around things will be a lot better.

M

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Thanks!

Unfortunately nothing helped. But will use these options in different scenarios. The best result using mblur is with micropoly renderer - up to 3 minutes for frame with 8x8 samples and mblur - anyway too slow especially comparing with micropoly/raytrace+ no mblur - 0:13 - 0:17 sec.

I hope 12.5 will improve rendering times significantly.

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