Preserving boundaries of the mesh with Decimate modifier - sounds like a new feature?

So in connection to my LOD research, I stumbled upon a problem. For LOD system to work on terrains (made of several meshes), meshes need to match on the seams/boundaries.

It’s not a big deal when it comes to original mesh cut up into pieces, but when I decimate it, boundaries of each piece change.

In Meshlab, there is a feature that keeps boundaries as they were, and decimate only inside area of the mesh.

Do we have anything like that with Decimate modifier? If not, is there a workaround? Thanks.

P.S. If there is nothing like that in Blender, maybe such feature could be added? :slight_smile:

The collapse option seems to preserve boundaries up untill a high decimation level.
You could always add the boundary vertices to a vertex group and use that group to excude those vertices from the decimation process (vertex group option in the collapse decimation options)

Presuming you have a messy mesh as output (triangle soup) it’s not too bad to add points on the bounderies after decimation and manually snap them…

though a @transfer UV tool would be handy to keep things tidy this way!

Vertex groups sound like a solution as long as that option works for most optimal decimation method (I forgot which one I found to be most suitable).

Manually adding vertices is not going to work simply because terrain might be split into 100 pieces or so. Unless there is an automated way of doing that :slight_smile: