Huge slowdown when using corona distance

[v.p.vlasenko]

I have few materials. When applied to object separately speed ranging 7-14M. When mixed in multilayer material with corona distance - speed is 700k +/-

Same problem with opacity. I have a landscape model + a lot of buildings with pools. Bottom of pools below ground level - instead of cutting geometry I used corona distance to cut it during render - speed dropped twice.

Maybe that's correct behavior with opacity, but 10 times slowdown with mixing materials looks strange.

[rowmanns]

Hi,

Is this described in the scene you already sent to me? If so can you describe which materials and objects I should look at. And some reproduction steps on how to reproduce this slowdown.

Cheers,

Rowan

(Report ID=CRMAX-265)

[v.p.vlasenko]

Yes, landscape model there (island)

There are 4 materials mixed in multilayer material. Each of those materials applied separately gives a way higher rays/s. Seems like from 7 to 14 million on my PC, but mixing them in multilayer gives something around 1M.

Actually I may be wrong and that not corona distance - I didn't tried a bitmap mask, maybe something with multilayer material.

Anyway, such slowdown looks weird.   

[Jens]

Was anything discovered regarding this? I'm having the exact same issue. Corona distance maps in a corona layered material results in a perfomance drop from around 20mil rays to 5-6mil.

Did some tests (see screenshots) and it's clearly the distance maps causing these huge drops in performance.

A big sinner is also having a refractive material (I'm projecting lakes on the terrain via a water material and distance map).

Sum-up:
no bitmap white base only : 31mil rays total
no bitmap white base layered with mix of 3 standard max maps (noise, cellular and falloff): 19mill
4k bitmap as base layered with mix of 3 standard max maps: 17mill
4k bitmap as base layered with 1 white base mat and 1 distance map: 15mill
4k bitmap as base layered with 1 white base mat 1 water material and 2 distance map: 7.7mill

For each extra (non refractive) material and distance map, performance seems to drop 2mill rays.

[rowmanns]

Hi,

This is with our dev team, unfortunately I have no further update at the moment.

Would you be able to provide your testing scene also?

Thanks,

Rowan