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agitat3d

Working with Levelsets

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Hi to you all :D

I have created a SDF Volume and am looking to manipulate the levelset data in order to erode the object. I cant seem to veiw any of this data so obviously modifying it is a problem. Any advice would be a big help as this is all new to me!? :)

Big thanks in advanced!

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Your friends are the IsoOffset SOP, the VolumeMix SOP and the Isosurface SOP.

Just to do what you're talking about the IsoOffset can do in a single step - it'll make a levelset and mesh it in one SOP, and it exposes a parameter to erode/dilate it right there.

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Your friends are the IsoOffset SOP, the VolumeMix SOP and the Isosurface SOP.

Just to do what you're talking about the IsoOffset can do in a single step - it'll make a levelset and mesh it in one SOP, and it exposes a parameter to erode/dilate it right there.

Hi Ya and thanks for your replies,

Well I had been playing with the erode and dilate params, however I found that it erodes the surface in a uniform way. I was looking to have patches of the object erode non uniformly about an arbitrary number concentric points on the surface. The erosion would eat ALONG and INTO the surface so I was looking to have some kind of access to data representing the volume. I could then manipulate the data in a flexible and efficient way to remove, translate etc parts of the volume.

I have been looking at an article by sony imagework on how they eroded the sandman and wanted to utilize houdini to do a similar thing. (See attached article, section 3). I know sony developed a hell of a lot of tools to asist them in the production however I would like to see how far I can push an off the shelf copy of houdini with existing operators.

Many thanks. :D

Ferreira_Levelsets_2007.pdf

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I think you can hack a few of the things by adding and subtracting, max'ing and min'ing values in SDFs in the VolumeMix SOP- but I think what you might be missing are functions to filter the Volumes (blur, etc) and a function to Reinitialize SDFs in order to fix them up after a bit of hacking. Unfortunately the neat SDF tools are trapped in DOPs right now; perhaps one day they'll make those neat functions available in SOPs.

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I think you can hack a few of the things by adding and subtracting, max'ing and min'ing values in SDFs in the VolumeMix SOP- but I think what you might be missing are functions to filter the Volumes (blur, etc) and a function to Reinitialize SDFs in order to fix them up after a bit of hacking. Unfortunately the neat SDF tools are trapped in DOPs right now; perhaps one day they'll make those neat functions available in SOPs.

Hi Jason,

Thanks for your response. Yeah I had noticed that DOPs done some really koul stuff with SDF! Well thanks for he advice and ive managed to get some half decent stuff working with volumeMix. My plans are to maybe generate some curves over the surface and spawn particles over them using the vol mix to subtract their volume from the initial geo. I just need a way to generate some decent noise and irregularity. Well, we'll see what happens.

Thanks again

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