flickering in cloud sim

[japetus]

I don't have access to post in the Phoenix Problems section for some reason, so I'm posting my question here. Feel free to move:

I did the Phoenix cloud preset (which is great!) but when I render out my sequence on our farm I get some dark blocky splotches. I have an object with lights traveling through the clouds. I'm rendering with brute force GI. The worst part is when the object starts coming through the clouds. I've turned down render steps to 20 and shadow steps to 25. The sim area is rather large, at 882x772 feet with a cell size of 7. I'm also slowing the sim down to .01 since I just need some slow moving clouds. I could probably even hold on a frame too. I'm gettng good sim results, just this darn flickering! I've attached a gif showing the problem...

[Svetlin.Nikolov]

Hey,

You can try turning off the Phoenix Light Cache in the Smoke Color options or just reducing the cache speedup.

Cheers!

[Svetlin.Nikolov]

Ah, also please send a mail to support@chaosgroup.com and they will correct your forum access.

[japetus]

Thanks, I think a number of things were wrong, I was using the vray sun, and sky, but switched to just using a normal vray light and hdr, and that seemd to solve that shadow problem. I also played with the lightcache setting you described which also slightly improved noise with in the cloud, but at the expense of render time. I think the big killer right now is I'm using displacement to get some more detail in my cloud, which is looking good, but I think it is causing further artifacting and makes it render still slower...is there any way to speed up displacement rendering in phoenix?

[japetus]

I'm doing more experimenting and might switch to use a texture in my smoke opacity slot instead of the displacement...seems to be not a bad result

[Svetlin.Nikolov]

Ah yes - the smoke displacement is terribly slow and we haven't gotten the chance to spend time optimizing it since it's not often used.

If you do keep a version of the scene with artifacts, would it be possible to send it over to Support so we can try to improve it?