I’m running into a situation where the decimation node just passes the geometry through unchanged.
the attachment limits are really low
Hi Willem,
Thank you for submitting this issue. I will try to recreate this case and check the node’s behavior!
When I’ll get more information, will message you.
Hi again Willem,
I tried on different setups a mesh with a similar number of vertices, but the node computed as intended. Can you please, provide a mesh, for me to recreate the problem exactly?
If needed we can sign NDA, provide a private link to a common drive or so.
Hi Leonid!
I’ve setup a repro and I learned that it works correctly when keep uvs is off, and doesn’t do anything when it’s on. At least for the mesh that I’ve tested on.
You can download the repro here: https://www.dropbox.com/t/UvqkCsXOn93izf70 (192 Mb, this link expires on the 30th of November)
I’ve just realised it might be the same bug I reported here: https://www.russian3dscanner.com/forum/index.php?topic=835.0, with the only difference being it does not hang indefinitely, but eventually returns control to the user.
The progress bar in the bottom left still says decimating though nothing is happening.
Anyway, I have since decimated these meshes using MeshLab, so if you’re short on time, the brush node crash I’ve just posted is affecting us way more, and is a hard crash so should be easier to pinpoint 
Hi Willem!
We checked all the math with your model in the decimation node pipeline.
When Keep UVs enabled node Decimate is prohibited to remove UV edge if it touches only one polygon. This allows us to avoid changing the boundaries of UV after decimation.
It seems that every UV polygon in your scan share no vertex with other UV polygons. So every edge technically touches only one polygon. Decimate basically cannot remove any edge and returns input mesh unchanged.
You can stitch your UV polygons in 3rdparty software. After that Decimate should be able to remove edges properly. Or you can just uncheck Keep UVs if you don’t need them.