Focus: testing and clouds

 I'm still putting a lot of time into testing True-Terrain 5. I have always loved modelling landscapes. Three dimensional places, in games and CGI art have been a constant fascination since the time of VistaPro, a procedural generator on the Amiga, in the 1990s.


Yesterday, I spent rather a lot of time looking at clouds. The VDB type. True-VFX's True-Sky can give VDB clouds a fringe in some situations. I was looking at the cause. Richard at True-VFX thought that the issue could be solved by changing the default space for a VDB from object to world. This turned out not to be the cause for my examples.

The dreaded sky fringe clouds - a reaction to True-Sky's atmospherics?

Conventional wisdom (and BD Design's tutorial on YouTube) state that the following parameters will balance nice looks against slow processing/rendering:




On the rendering panel, under Light Paths > Max Bounces:

Volume sets the maximum number of light bounces for scattering. The higher the number, the more light is scattered through the cloud, making it less dark.

Volume 0

Volume 128

Max Steps is the maximum number of steps in a render before the process gives up, kills the light ray and moves on. Increase the number to protect against excessively long rendering times.

Maximum Step Size 2

Maximum Step Size 128

Space sets whether a volume has the same density and detail regardless of its size (object) or adjusts these parameters based on the world (world). When set to world, increasing the size of a volume will result it its density and detail increasing. When set to an object, increasing the size of the volume will not impact density or detail.

The Step Size is a property of the actual volume rather than the render engine. It sets the distance between volume samples. Smaller makes for more fine-grain volumes. The default of 0 tells Blender to use the voxel size. I'm told that there's no point going below a step size of 1 for VDBs, you won't get any more data out.

Going with the high detail (Step Size 0), you see the voxel "steps", rather like the volume is a giant Minecraft construction.

Step Size 0

Step Size 24

    Pushing the step size to 40, the detail is washed away, and renders are a bit faster, but steps are gone.

Step Size 40

References:


A great tutorial on note setup for great Clouds (with some mention of render settings):