Forums Technical Discussion Volume VOP & noise

Volume VOP & noise

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circusmonkey
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Hi Brains trust

In this example file I have a volume made from a curve. Currently noise is applied to the whole volume along the curve. This got me to thinking

1) is there a way to control density down the curve via a attribute ie a ramp reading Cd

2 Is there a way to add noise to just part of a sdf volume using a volume gradient. from say 0 at the boundary to 0.5 and have only that area affected by noise.

Any advice greatly appreciated

Rob

Attachments:
volume_curve_noise.hip (146.6 KB)

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Enivob
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One way might be to place a carve before you convert your curve into a volume.
Activate Second U and you will have two sliders that can dial in any portion along the path.
The Carve can also Keep Inside or Outside so you could setup a merge of two volumes, one with noise and one without whose area is derived from the Inside and Outside portion of the carve.
Then you could animate the U and V as needed to make the noise travel or appear anywhere along the curve.

Attachments:
Untitled-1.jpg (128.6 KB)
volume_curve_noise_140.hipnc (143.2 KB)

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circusmonkey
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Thats an interesting idea, I was hoping to more carve into the volume using some vops for the learning experience.

Rob
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Doudini
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Not sure if this is what you are looking after,
Make your own Volume Raster HDA, use 2 vdb one for density and one for color. We can use wrangle to map fe. stroke perssure or Cd for density. When we take this to the Volume VOP we will have the Cd parameter in there. Use a Bind Node to read it out and plug it into amp of your noise.

attached is the hip file with 2 example. 1 just using a basic density from the Cd. Second will Raster with the Cd value and therefor we can use it in Volume VOP.use

Attachments:
mbPainter_ExampleNoise.hipnc (179.6 KB)
vdbNoiseGradient.png (144.7 KB)

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JordanWalsh
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You could also have a noiseAmp attribute on the points or your line then use a point cloud open + point cloud filter to read in the attribute then wire that into the amplitude of your noise
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MrReedSmith
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You could just make a grad attrib on the curve which will give you a 0(white) to 1(red) value and based on the grad you could limit the noise and then just use grad to make density, hopefully that helps, I have a also attached a screenshot of my scene, maybe that'll make it a little more clear

Attachments:
Volume_By_Grad.JPG (118.2 KB)

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circusmonkey
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Thanks for example I am going to have a go with this

Rob
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circusmonkey
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Great examples …. will post up a few results

Rob
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