Time-lapse clouds viewed at satellite level..?

[soopagenius]

Ken Perlin, he of the eponymous noise function, has a nifty little demo you might be interested in. Before you run the applet, be sure to click the "Texture on" button -- it's lame without it:

http://mrl.nyu.edu/~perlin/experiments/vpuff/

It's a bit of a cheat -- just a series of 2d images composited together -- but the illusion of a true volumetric approach is convincing.

As for how to implement this, one way is to do it as a Renderman shader, particularly if you use another function to perturb the domain to get the swirly effects you seek.

Good luck,

Kevin Atkinson

[withnail]

Hi, thanks for that.

Looks pretty interesting, -I'm just not sure how I'd be able to use that technique. We don't have Renderman here, and I've no experience with that software in the first place. The shot needs an answer in the next two days! Whatever I come up with will have to be Maya based...

I think I'm going to have to go down the procedural texture route, simply because of the sheer amount of detail I need to show.

Don't know quite how I'm going to do it though!

[BigSky]

I'd suggest this,

Make a fluid3d and replace with the cloudbank preset.
Turn the velocity and the density and velocity to dynamic grid. You will need to set the shading gradients to dynamic as well.
Use the paint contents tool to draw in your desired shape, presumably a vortex or something. Use the noise texture to make some changes over time for your cloud base texture, things like texture time, frequency, threshold, etc.
If you set you texture type to grid, then you can use maya fields as well, so a vortex with a max distance in a sphere volume will set the centre spinning, etc. So long as you keep your samples regulated, and can stay away from self shading...this will be an effective solution for you. :)

[withnail]

Thanks BigSky,

I think I see where you're coming from, trying to form the familiar circular form of a hurricane seen from space, but I'm actually after something different in this case.

I did have to create a hurricane earlier in the project, which I did by using a nasa image as a displacement and bump map on simple geometry, then twisting the center using the soft modification tool.

The monsoon is a long, thick bank of clouds, creeping up the side of a mountain range, bubbling up from nothing and becoming more dense, before dissipating away over the mountain tops. All this has to happen in a shot wide enough to see the whole mountain range (and the earth's horizon) from space, but because it's hi-def you can also see lots of minute detail within the cloud bank...!

I had to get a test sorted for tomorrow, so I've had to use plan A which was just pushing a procedural through a nasa shot of an actual monsoon, and then slightly deforming the geometry. Not perfect but it gets the point across.

Thanks for the help anyway! :thumbsup:

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