hey guys,

Has anyone figured out a way to clean up the pixelated edges around a cloud when you look really closely at it? mine end up very pixelated and blurry. Im currently rendering out at 720p HD resolution using 3x3 Pixel Samples with a transparent sample of 4. let me know if you want my .hip file.

heres my most recent render, can anyone lend me a hand?

http://imgur.com/pgiVuqe [imgur.com]

Maybe try tweaking Volume Quality?

http://www.sidefx.com/docs/houdini12.5/props/mantra#vm_volumequality [sidefx.com]
http://www.sidefx.com/docs/houdini12.5/render/volumes [sidefx.com]

Those are actual voxel boundries. Try gauss and 1.5:
http://www.sidefx.com/docs/houdini12.5/props/mantra#vm_volumefilter [sidefx.com]

The volumes are quite low resolution for the given scene. In practice it is advised to have very high resolution cloud volumes saved to disk. Load them in and then decrease resolution as you populate frustum volumes set to the camera.

You can populate multiple clouds in to the tapered frustum volumes. Sensibly divide in to multiple frustum volumes: hero, foreground, mid ground, background, wispy upper layer, etc.

As for handling lower res volume clouds, yes Volume Filter set to Gaussian and 1.5 will reduce/eliminate the aliasing of the clouds at the cost of reduced detail but then you never had that detail in there to begin with. The box filter is the default as it works well with very high resolution volumes and is very fast to compute. Faster than Gaussian.

The Volume filter is used to convert the volume primitive in to micro-voxels for rendering. The size of the micro-voxels is determined by the Shading Quality and Shading Quality Multiplier. But if the input voxels in the volume are too large, then you will just get sharper aliasing of the volume. Applying a blur filter such as Gaussian when Mantra constructs the micro-voxels is the only way forward.

One other approach mentioned at the top is to re-sample your volumes higher in SOPs and then render out. Still a softening effect is had but you can get rid of the aliasing artefacts.

If you wish, you can populate a net new frustum volume set to your render camera and then merge in your volumes in to this higher resolution frustum volume. That way you can preview your volumes prior to rendering, or not.

See the example file attached.

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To be honest, there is no excuse not to take your machine to the limit then back off a bit to avoid going in to swap. That means on Windows, kill all other apps, grab a coffee or two and watch the performance monitor to push the machine as hard as you can as you create the volumes, cache to disk then render.

It's time vfx td's/artists push for higher disk quotas per shot! LOL.

Web browsing is for the weak. Read a book. Fill up your memory to the max! No excuses these days to have under-sampled volumes, especially with VDB's.


Good Luck.

jeff
It's time vfx td's/artists push for higher disk quotas per shot! LOL.

Haha this made me laugh, thank you Jeff. And thanks for the hip! It looks quite interesting, I am going to do some clouds for an upcoming project so I'm sure it will be helpful.