Hello,

If you check the little zip file, you will see some images of volume render.
I add some displacement on the smoke material.
The anim is a camera mouvement, the cloud doesn't move but the displacement is not “stuck” on it. It follows the camera. It like the displacement is “camera projected”.

-Is it normal ?
- If it is, why is it normal ? Is it due to the fact the volume is no geometry ?
- How to avoid this behavior ?

Thanks for your help.

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Vincent

Hey there,

try dive into your smoke material and look for the noise node (probably a Turbulent Noise), append a “Rest Position” node into it's Surface Position input. I took a look at the smoke materials that's shipped with Houdini, only BillowySmoke and WispySmoke have noise parameters and they have “Rest Position” node inside of them so they definitely works.

Are you using a custom smoke material you made, if yes… “Rest Position” could be the missing link!

As you've noticed it following the camera. By default, texture and noise are in camera-space and Rest Position is used to convert it to texture-space or object-space.

If your attachment is a fluid simulation, it needs to have “Rest Field” which is created when you set up your simulation using shelf tools. You could also search the forums and help docs for more details. Good luck!

eitht.

so obvious …
Thanks eitht.

Works fine now.

OK !

My cloud shading test is now complete …
http://vimeo.com/23623888 [vimeo.com]

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Vincent