More Cloud Confusion

[cyphyr]

Well for a start you'll need to plug in your distance shader to some sort of camera, render cam or otherwise.
Richard

[rcallicotte]

Well, it's working, though.  I have successfully isolated the cloud.

I'll try it with a camera to see if it then works logically.

[old_blaggard]

Back to the original question in the thread: I've done some experiments to confirm what I originally thought.  Hetzen is basically correct: the cloud shader is fed a bit of 3D noise from the cloud fractal.  The cloud shader give a complete image of the shape of the clouds.  The density shader only lets you see one plane - specifically, the X-Z plane with Y=0.  This is true for all shaders - when you have no displacement applied, you will always see what the shader looks like at Y=0.  You can confirm this by using a transform shader to subtract the cloud altitude from the density shader's Y position, and you will get the shader looking more similar to your actual cloud distribution.

[rcallicotte]

@ob - Title says Cloud Confusion.  This is a Cloud Confusion - the Distance Shader doesn't seem to work as prescribed.

[cyphyr]

Cheers OB, this is finally starting to make sense.

I can now use the transform shader to sensibly preview cloud formations. Brilliant !

Attached is a low octave cloud structure (just for simplicity) and screen cap.
The top window in the input seed density fractal. As you can see there is mismatch!
The window below is the final cloud output, and on the right is the density fractal transformed -2000 (the altitude of the cloud layer).

As you can see although the match is not perfect its good enough for jazz nice...

Thanks

Richard

ps gona go back and cross out my wild ideas 

[Oshyan]

Interesting discussion. You might consider this a bug in that the "shader preview" for the cloud noise seed is not showing what will actually be produced, however (and unfortunately) in a technical sense it is correct as the cloud noise seed (and any other noise function) can only ever show one point in the 2D noise plane, and the shaders that depend on it later in the chain may sample elsewhere in the shader. Since you can connect 1 shader to multiple other shaders, there would be no way for the shader to determine how to offset its preview display, thus using 0 for altitude (Y) makes sense. It's one of those counterintuitive things that actually makes sense in the long run, and is sadly very difficult to communicate clearly.

I'll have a think on whether there's any better way to handle this. Having a preview for the cloud shader itself and having that open while tweaking the density fractal would help I think.

As for the Distance Shader, as far as I know it's still working as it should. It would be best to post a separate thread about those problems though.

- Oshyan