Hi guys,
I need your help! I want to create a planetary view with moving clouds, to be more precise, of a spinning hurricane/typhoon. The problem, it needs to react to the lighting and the animation should loop.
But first of all, this is what I am talking about:
This one does not loop, so it is easier, but I would like to achieve something like this.
I tried several methods now, but nothing looked good.
From just taking a photo of a hurricane and generating a normal map … nope.
Trying to fake a height map and testing POM… nope.
Creating a hurricane VDB and rendering the necessary textures, like height an try it again … nope.
Trying to use 6-way-lighting … nope.
Trying to implement raymarching … nope.
So … yeah. I am out of luck. How would you tackle such a problem? Maybe I was on the right path, but only what I did was not good enough.
Need you help!
Thanks and have a nice day 
Hey!
At such scale, I think POM is really overkill. Look at actual space views of hurricanes, you don’t actually see much depth change!
I’d just make a simple hurricane texture, then draw a flowmap, which is basically a texture containing direction vectors that will be used to add motion to your hurricane texture. Here’s a video showcasing exactly what it does and explaining how to draw flowmaps inside Blender. This is a common technique that you can see used in lots of games for things such as moving clouds on skyboxes or flowing water.
You’ll also need to write a flowmap shader, but you should be able to find tutorials on how to make just that for whatever engine you’re using.
As for the lighting, if you look at your reference you can see that the hurricane is just overlaid on the planet texture, which means it is lit in the same way as the planet. At such scale I think this should work fine for most lighting conditions (again, look at actual space footage!), but if you think that wouldn’t work for you, maybe try putting the hurricane on a second sphere slightly bigger than the planet, and add some subsurface scattering on it? I think that using the hurricane texture’s alpha channel as an SSS mask would work well enough. You could also generate a normal map from that hurricane texture and distort it with the flowmap too, but I don’t think you’d really see much difference.
