Volumes + Mist Rendering Artifact

Hi All,

This is my first post on the forums, but I’ve been playing around with blender for years. I’ve recently picked up 2.58, and discovered, to my joy, it finally has true volumes!

I spent a few days working on a scene with clouds, and I added mist so they didn’t end so abruptly, and started rendering a flying-through-clouds scene. It seems, though, that the way the Z-Buffer is calculated for the volume is using the bounding-object, and not the mist itself (see picture). so there’s a stripe of mist in the top portion of the screen.

Does anyone know a way around this? I’ve played around in the compositor for a while trying to create some sort of mist-like work around, with little success.


Consider the fact that the volumetrics is based on raytracing and mist is a simple scanline-based effect that’s been in Blender since it was open sourced. Scanline effects have traditionally not worked well with features that use raytracing.

Since mist works technically like a volume it would seem to me you should try creating a volume material that covers the whole scene and given an extremely low density, it will take longer to render, but should work better because you’re not trying to use an old scanline effect that may have never been enhanced to work with raytracing.

The clouds in that scene is a volume material (in version 2.58) with 0 density, multiplier 9, and some layered perlin noise textures to affect the density. I turned on “raytrace” for the Transparency method on the volume. (See image below)

I’ve tried covering the whole world with a volume, the issue I run into there is with shadows – it just casts one massive shadow through the whole scene. Also, it does some weird Z issues again with the clouds, just different. I don’t think blender likes volumes-in-volumes. (Other picture below – volume red for visibility).

Good idea, though… just didn’t work. Any more ideas?