Hi,

I'm trying to create a planetary atmosphere VDB that has some density and colour gradient from the earth surface to the outer atmos that I can control in another DCC with Redshift. Anyone have any guide steps / advice on how to achieve this?

I started with a sphere and vdb from polygons obviously but trying to set up at least a colour ramp or something in there that I can use in my volume shading - export the vdb Cd value if that's possible?

Attached a diagram, any advice would be appreciated.

find Jon Parker on GitHub
jpVolumeLayers

Thanks.

I’ll take a look at that and see how I can adapt it. Hopefully I can export things and it’s not wholly dependent on rendering in Houdini.

You can definitely do this with VDBs, but I’d separate density from colour rather than baking everything into one field. Start with a sphere → VDB From Polygons to create your fog volume, then generate a radial gradient using the distance from the sphere center (Volume VOP / Volume Wrangle works well). Use that gradient to drive density falloff from surface → outer atmosphere. For colour, either create a separate volume field (Cd or custom vector field) and export it with the VDB, or keep colour entirely in Redshift and remap based on volume position/density for more flexibility in the other DCC. Usually density + temperature/gradient masks exported gives cleaner control than embedding final colour directly into the VDB.

Since you said your goal is to get this VDB into another application for rendering, I'll give you a heads up on two problems you might run into, just so you are aware.

1- The color gradients that you see in planet atmospheres come from the light angle. So if you bake the colors into your VDB, you are essentially baking the lighting. Generally, it's better to use a shader to create the colors, like the Jon Parker one mentioned above, or the built-in Karma Atmosphere LOP, which gives you more than just a sky. If you pull back far enough, you'll see that it's a full spherical planet atmosphere.

2- VDB resolution. The Earth's atmosphere is very thin. It's hard to get enough resolution using square voxels to represent a thin spherical shell. This is another reason that doing color & density in your shader is important. Depending on your shot, you might get away with it, but if your camera is going to be close to the atmosphere and your not going for a stylized look, you'll probably start to see the voxels if you bake color and density into a VDB. The solution to both of these problems is to make sure your target rendering application has a good atmosphere shader.