I'm tinkering with vellum and have a weird issue–when I use a plain grid as the cloth object and run it through a remesh, random points are/act as if they are pinned (they are given a @mass of 0), even though there is nothing set as pinned in the vellum constraint node.

I've emptied the cache, restarted, even tried a new grid with slightly a different initial subdivision count, and the result is the same–various points stay in space, pinned (although with differing initial geo point counts, the points that don't move are different).

A grid without remesh works fine. A planar patch actually works fine. I've tried various other objects, all run through remesh nodes (and without), and they all work fine. I could even assign those points a new mass through a wrangle, and that worked fine, but it seems like for something as basic as a remeshed grid, this shouldn't be happening.

What am I doing wrong here? Or is this just why god and SideFX made planar patches?

An addendum/solution from my od|force posting–the problem was solved by changing the cloth setup vellum constraints from “calculate varying” mass to “unchanged”. When plopping down just a vellum constraints node, unchanged is the default, but when using the “vellum configure cloth,” the default is calculate varying. That did the trick.

well, technically it's not solved since then you don't get varying mass which may be important

the real problem is that remeshing seems to sometimes create 0 area triangles at the borders, which may cause 0 mass points down the line when using varying mass (which is computed from area)

so to avoid the issue without having to sacrifice varying mass, you can append Measure SOP (after remesh) to measure area per poly and then Blast SOP to delete 0 area polys (@area=0), which you will visually not notice cause they are 0 area anyway

Even better, as it's a solution instead of a workaround. Worked like a charm–thanks!

Came here for the exact problem and tamte solved it instantly. Amazing!

or you could use the v1.0 of the remesh Sop instead if the 2.0

Hmm interesting. Thanks for the different method carthick. Good to know.

or submit bug if it's still happening, because last thing I remember this was supposed to be fixed in 18.5.612

Houdini 18.5.612 Fixed a bug in Remesh 2.0 which caused degenerate triangles around boundaries and hardended edges. Thu. June 17, 2021