I've been noticing some artifacts when creating a surface with the ParticleFluidSurface node, and finally just did a simple test to isolate them. There seems to be some weirdness in the implicit field that it's generating, where you can often end up with stray polygons where two particles are just outside their respective areas of influence.

In this screen shot, the top surface is from the PFS node, the bottom just two metaballs Copy SOP'd to the same points and ConvertMeta'd. I don't see why that strange mass in them middle is there in the PFS example. I'm seeing the same symptom in the results of fluid sims.

Any ideas? I'm including the test file as well. This is with 9.0.768, BTW.

Thanks

This is a known issue which is being worked on.

Aside from having a higher density mesh on your surface/more particles… there's not really anything you can do.

You could manually delete those polygons on given frames as well.

Allegro
This is a known issue which is being worked on.

Aside from having a higher density mesh on your surface/more particles… there's not really anything you can do.

You could manually delete those polygons on given frames as well.

Any update on this? This test file has the same artifacts in 9.5. I was looking at Robert Magee's liquid metal tutorial from 3DWorld again, and these artifacts from the particleFluidSurface node make things a bit messy. It's a shame because otherwise the surface looks really good in a blobby/ goopy metal sort of way.

I was able to clean up your first example by changing the Surface parameters. In particular “stepsizex” and “radius scale” and “surface distance”

probbins
I was able to clean up your first example by changing the Surface parameters. In particular “stepsizex” and “radius scale” and “surface distance”

Yeah, I've been able to get rid of most of the artifacts by tweaking the parameters; I guess my point is you shouldn't have to, IMHO. There's really no way that two points spaced one unit apart should give rise to that weird surface in the middle in that test file. And if you fix the artifacts with parameters for one frame, they show up at another position or in another part of the animation. And then you're changing parameters not based on the appearance,tightness, etc. of the surface, but whether or not they cause artifacts. If I want the “liquid man” model in question to be big and gloopy looking, I'm kind of out of luck without artifacts. Things like increasing particle count, changing stepsize, and whatnot can dramatically change the overall look of the surface.

/rant

In this case I was able to use Connectivity/Partition, Measure, ForEach and AttribPromote to remove groups of connected primitives below an arbitrary overall surface area, which generally worked fine, because there's really only one big connected surface you care about. If there were lots of little drops that probably wouldn't work. Also, some of the artifacts are not disconnected from the overall surface, but in this case they weren't too objectionable.

Anyway, while I agree that you can work around the artifacts, I would still rather not have to.

Edit: Oof, this whole post comes off way more rant-y than I meant. So, I should add, Houdini's always the bees' knees and I've gotten a ton out of your tutorials, Peter, thanks.

I had the same problem and found you could reduce this to some degree by scaling up your system, running the surfacer, and then scaling down again.