I've just been playing about with the ISO surface and ISO offset nodes. I've read the help file on these two, but I don't really understand it.

What's an ‘implicit’ surface and how are these nodes best used?

If you build a volume, from a box in this example, the area inside the box is subdivided into voxels. Each voxels contains values that are different throughout the voxel. Some areas of a voxel will have positive values and some areas will have negative values. The implicit surface is the 0 (zero) boundary, where the values drop to zero.

Thanks for the explanation.

I still don't exactly know what I'm looking at, but I assume looking at the examples these nodes are for building voxel grids and volume based objects then?

I suppose being used to Lightwave Hypervoxels its hard for me to grasp. If your familiar with Hypervoxels, you will know that they create puffy volumes for thick volumteric smoke.

Would I be needing to use one or both of these to achieve a similar effect?

I'm not disparaging Lightwave, I started on it when it only ran on Amigas, but you can get rid of the Hyper part of hypervoxels. That's just advertising “hype”.
Their voxels behave exactly the same way, that lightwave doesn't let you see the zero boundary is too bad.
It's like polygons, the interface may change between apps. but the math is the same.

So, the attached image is a more complex example. Each box is a voxel, and the green geometry represents the zero boundary. The space between the green geometry in each voxels contains the values that make up the “fluffy” stuff, once the volume is built. The values within the fluffy stuff will range “randomly” between -1 and 1. If your fluffy stuff is moving it needs a direction, that would be 0.

Thanks - looks pretty interesting!

Look like in that example you have randomised the zero boundary with a noise function or something?

I don't really understand the maths behind volume geometry, so terms like ‘zero boundary’ is a bit lost on me really ops: Perhaps if I find something on that it will help me to know what's going on further.

Cheers!

Hi

I have a grid with implicit function values in every vertex in separate file. How can I make Houdini to use them instead that function, which is parametr?

I understand, that it's not easy and it's not a few minutes deal, but may be you can advice something.

Thank you.

On a side note, you can also use ISO Surface SOP as a visualization tools for any implicit equations in math class which most of us slept through.

You know, I sometimes wondered if anyone is going to write a graphing calculator SOP someday.