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Cycles smoke adaptive domain problem
Closed, ArchivedPublic

Description

Windows 8 geforce gtx 770

Blender Version
Broken: blender-2.73-5ea243b-win64
(any version with smoke/cycles enabled)

When the adaptive domain from a smoke simulation changes sizes the smoke renders differently from frame to frame when using cycles and the cpu (eg flickering, shifting) , this was a problem with the blender internal render as well but there was a work around by duplicating the domain, this does not seem to work with cycles.

Exact steps for others to reproduce the error
render out a smoke simulation in which the adaptive domain is changing sizes locations slightly

Details

Type
Bug

Event Timeline

Patrick A (patmaniko) set Type to Bug.
Patrick A (patmaniko) created this task.
Patrick A (patmaniko) raised the priority of this task from to Needs Triage by Developer.

Please attach a .blend file to reproduce the problem, as mentioned on the bug submission page, thanks.

I don't know this domain duplication trick, how does that work? It we can figure out how that's different from just rendering without duplication then that might give the proper solution for both Blender Internal and Cycles.

Sergey Sharybin (sergey) triaged this task as Needs Information from User priority.

The workaround was after the simulation was baked you would duplicate the domain and then in the texture section of that new domain you would reference the old domain object that actually contains the simulated smoke, so the domain would no longer be changing size but would contain the correct voxel information.

This video does a better job of explaining it/showing it
http://www.youtube.com/watch?v=B_0gb5cJ0DE&t=30m11s

along with this thread
http://www.elysiun.com/forum/showthread.php?284800-Smoke-flickering


Hopefully I attached the file correctly, the problem occurs most apparently between frames 108,109,110

Thanks for the quick response btw you guys are awesome!

Yep can confirm this... But if I understand correctly this is a known issue with adaptive domains (@Miika Hamalainen (miikah), is it?). In this case we wouldn't consider it as a bug, rather than a todo.

Julian Eisel (Severin) raised the priority of this task from Needs Information from User to Normal.Jan 1 2015, 9:10 PM

I haven't used Cycles volume rendering, but at least with Blender Internal the issue was related to the "light cache" and changing object size.

When domain size changes so does the volume used as boundary for the light cache. Therefore when we observe light cache resolution from scene perspective (per scene length unit) it's constantly changing. This causes certain details in the volume shading appear differently and flicker.

As @Patrick A (patmaniko) mentioned, a workaround was to render smoke using a static sized volume only using the voxel data and mapping coordinates from the original domain. No idea if or how this works with Cycles.

Okay, but at least this is a known issue with adaptive domains, so this shouldn't be considered as a bug. I'll close the report for this reason. Sorry, but we have to follow the rules strictly to keep our bug tracker organized

Nevertheless, thanks for the report @Patrick A (patmaniko) :)

Julian Eisel (Severin) closed this task as Invalid.Jan 1 2015, 9:48 PM
Julian Eisel (Severin) claimed this task.

I wouldn't close this task yet, Cycles does not have a light cache so that can't be the problem. It has to be something else, and it would be good to understand what that is before making any decisions.

Alright, wasn't aware of that

Eeeh, indeed this report was closed too fast, I'll have a look next days,

does anyone have any suggestion for a work around?

@Patrick A (patmaniko), i'm not really sure about workaround and i can't really see flicker across frames 108-111 using your blowninup.blend. What are the steps needed to see the flicker based on this file? It might also help testing latest buildbot build.. And if you still will have flickers it worth uploading two-three frames with flicker, so we'll know what to look for.

Also, i'm using backed simulation, which is always a good idea anyway. Worth trying that from your side as well and see if it has any affect on flicker.

Thomas Dinges (dingto) closed this task as Archived.

@Patrick A (patmaniko)'s account is deactivated, so closing this task until we get the infos sergey asked for.

heres a file/video for the flicker problem

viewport render (looks ok?)

https://www.dropbox.com/s/hg81dkuprswa53n/smokelowviewportflicker.avi?dl=0

cycles render

https://www.dropbox.com/s/br6mxbpqz5qegnh/smokelowflicker.avi?dl=0

file

To anyone who is still reading this I figured out a solution , lower the volume sampling size below .64 (i use .16) the flickering should go away