Volumetric noise

[TiMc]

Hi,

I'm having a slight issue with a volumetric shader that I'm working on and was just wondering if anyone could possibly help.

I've pretty much adapted the shader used for the heavy smoke example in the fx tools shelf but I've come across an issue when I try and change the type of noise being applied. In the original shader a turbulent noise is used but I would like to use the anti-aliased noise. However, I appear to get some errors when I swap the anti-aliased noise in. I've included two images which should help to demonstrate the problem.

As you can see there's an issue with what appears to be the bounding box of the metaballs when the two intersect. Has anyone got any idea why this occurs? I've tried with other noise patterns such as the high-low noise and the same thing occurs.

Any help would be greatly appreciated.

Thanks

Edited May 15, 2009 by Tim C

[mangi]

Hi there,

well it's kind of hard to see whats going on with your hip file.

I guess If you had upload some one could look into to it.

Anyway , I did 2 metaball +voulume to try an get this issue you are getting , but had no luck, works fine in the way I made it.

like I said not to clear how you prepared this, with out a hipnc.

cheers

mangi

[Wolfwood]

Looks like its being clipped. When using the metaimport / forpoints() the noise is only really well defined where the metaball's density != 0. In this case it looks like your noise is being clipped away since it falls outside this region.

[mangi]

Hi there,

well it's kind of hard to see whats going on with your hip file.

I guess If you had upload some one could look into to it.

Anyway , I did 2 metaball +voulume to try an get this issue you are getting , but had no luck, works fine in the way I made it.

like I said not to clear how you prepared this, with out a hipnc.

cheers

mangi

Hi there, I made a quick time , 2 metaballs , is there any clipping here, can you see some thnig strange going on?

thanks mangi

One second , gona make another quicktime, without the noise animation , That way it can see the ani without noise over time

here it is n thanks for any comments

Ps I am doing these things just for the sake of things cheers

cloud.mov

cloudnn.mov

Edited May 16, 2009 by mangi

[TiMc]

Hello guys,

Thanks for the responses.

I've just recreated the situation using the smoke:heavy shader and attached the hipnc file.

It's the exact same shader as in the smoke:heavy example. If you bake out the metaballs and render them using the mantra1 rop there is no problem.

However, if you go inside the shader /obj/geo1/shopnet1/fx_vol_fog, then go inside the mball_loop node, then into dens_noise (these are both highlighted in yellow netboxes) you will see where the noise is applied (again highlighted in yellow).

The original shader uses the turbnoise1 node which should be connected when you open the file. If however you swap in the aanoise1 node and rerender, you can clearly see the clipping of the noise.

If anyone could shed some light on how to overcome this it would be greatly appreciated.

Thanks again.

Tim

volumetricNoise.hipnc