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#1 2016-10-11 03:02:44

shawn_kearney
Member

Volume Noise Coordinates Details?

Hi, I am wondering what exactly the voxel shader's noise coordinates are exactly. I'd like to get advected noise onto Houdini volumes. I assumed that it was the Rest field, but that didn't seem to do much.

How can I go about calculating this data into my VDBs?

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#2 2016-10-11 09:38:35

hulud
Guerilla dev, the guy to hug

Re: Volume Noise Coordinates Details?

Hi Shawn,

The voxel coordinates reproduce the Maya Fluid coordinate noise : the simulation starts with a vector3 coordinate grid filled with a simple 0->1 gradient values on each axis. This grid is advected during the simulation. During the shading, you can use the object/world position as coordinate for the noise or, use those advected coordinates, which deform the noise function with according to the simulation. The effect is good to get details but it's not as good as a real simulation.

This is for the theory, now in practice in Houdini, I'm sure you can get such coordinates grids (probably more crazy ones) but I could not tell how to do. Anybody ?

Cyril


Cyril 'Hulud' Corvazier
Guerilla developer
http://www.mercs-eng.com

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#3 2016-10-11 18:48:55

shawn_kearney
Member

Re: Volume Noise Coordinates Details?

I was kind of wondering if it was something like that, but I didn't want to go about it blindly. Yes, I can get to the voxel coordinates in a Volume VOP. So if I fit the voxel object space to a 0 to 1 range and output these values it to a vect3 field and names it "coordinates" this should work, correct?

I might have tried this, but it wasn't a normalized range and may have been signed values...

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#4 2016-10-12 10:13:32

hulud
Guerilla dev, the guy to hug

Re: Volume Noise Coordinates Details?

Yes correct, feel free to send me a sample if you want me to check.


Cyril 'Hulud' Corvazier
Guerilla developer
http://www.mercs-eng.com

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#5 2016-10-12 17:33:37

shawn_kearney
Member

Re: Volume Noise Coordinates Details?

Cool. I have to get on to other assignments right now, but I'll try at this again in a week or two.

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