Smoke Details

[Naeem]

Hi all,

I am working on a shot where the camera has to go through a huge wall of smoke. I was looking for some tips on how to get a good amount of detail in the smoke while keeping the cache size and render times reasonable. My smoke container is 30x20x15 and with a division size of 0.05 I am not really getting enough detail - I tried going as low as 0.03 but then the cache size is getting out of hand. I have disabled all the unnecessary fields on the DOP Import to keep my cache size to a minimum. See attached screenshots to see how the smoke looks just as the camera is about to go through it.

For the render I am using PBR with Blackman volume filter with filter width set to 1.25 and Shading Quality Multiplier set to 2, Pixel Samples set to 8x8, Volume Quality at 0.25, Volume Shadow Quality at 0.5 and Transparent Samples at 16. Anything else I can do to improve the render?

Edited September 16, 2013 by Naeem

[slamfunk]

Hey dude,

you've tried adding noise in the shader? Or creating a turbulance field for you sim to pass through?

Edited September 16, 2013 by slamfunk

[Guest tar]

I am working on a shot where the camera has to go through a huge wall of smoke. I was looking for some tips on how to get a good amount of detail in the smoke while keeping the cache size and render times reasonable.

How large are the cache sizes and how long the render times? Detail takes both!

A few things to try; smoke clusters shelf tool, manually changing the resize_container size to the frustum you can see, using an Uprez container cropped for the part you are flying through and mix it in compositing with a low res.

[Naeem]

Hey Billy - not using noise in the shader but I do have a turb field. Marty, the cache size is approx 1-2gb per frame and render times when the camera is close is about 25-40 mins per frame.

[Guest tar]

can you upload your scene setup? The mantra setting also seems quite high, maybe your lighting could be optimised

[Naeem]

Here you go.

od_Smoke_Details.hip

[Guest tar]

Thanks - I will try to go through it later, in the mean time would a LOD box setup work where you would fly through it - see attached pic

[Naeem]

Thanks - I will try to go through it later, in the mean time would a LOD box setup work where you would fly through it - see attached pic

Not sure since I've not used something like that before - I could use the frustrum to optimize the render and I am trying to find a right balance for the value of Volume Quality on the Mantra ROP as well since I think that will help quite a bit. But the important thing I am trying to figure out is improving the level of detail in the sim while keeping the cache size to around 1-1.5gb per frame.

[Guest tar]

you can also render compressed files to keep the file size smaller. ie. .bgeo.gz

[Naeem]

Yes I could, but I guess that takes a lot longer to load the files.

[Guest tar]

Not sure since I've not used something like that before - I could use the frustrum to optimize the render and I am trying to find a right balance for the value of Volume Quality on the Mantra ROP as well since I think that will help quite a bit. But the important thing I am trying to figure out is improving the level of detail in the sim while keeping the cache size to around 1-1.5gb per frame.

How are you going to use the frustrum to optimise the render? mantra does that automatically.

The slow part of the simulation is the amount of extra voxels being processed and written to disk, then read back in. That's where you want the optimisiation.

[Naeem]

Sorry I meant to cache the sim - I believe there is way to use the camera frustrum to optimize the caching process. I am running some render tests to optimize my render times right now and I think they are pretty OK - now as long as the level of detail in the smoke is proper I should be fine.

[JaydenDP]

Convert the sim to VDB before writing it out is a good way to optimize cache size. I get up to half the size doing that.

[ikarus]

If the smoke isn't fast moving you should probably utilize the noise parameters in the pyro shader along with the rest fields.

[Guest tar]

If the smoke isn't fast moving you should probably utilize the noise parameters in the pyro shader along with the rest fields.

Always wondered about the noise. Can it look any good/any examples out there? My tests always looked lacking.

[Naeem]

@ikarus I did try the noise on the shader and it didn't help much - maybe I should give it another go. @JaydenDP - Thanks. I am using VDB as well to optimize the size cache and I am saving about 30%.

[Naeem]

Here is a new render with much higher details - compared to the old one. Things I did - increased the disturbance to add smaller details, lowered the division size a bit more (0.05 v 0.03), used VDB to keep the cache size in check (about 20 - 30% lower file size). I might try adding some noise to this to see if it helps but I am pretty satisfied with how it is now.

Edited September 19, 2013 by Naeem