Hi @pieterso​,

Have you already given the SolidDissolver a try? It's a new official transformer in the FME 2022 betas that could simplify the complexity of each object by dissolving common boundaries to create larger solids.

You might want to experiment with the Group By option in the SolidDissolver as well depending on what your data looks like. For example, if all your solids share a boundary it'll become one output feature, so if you want to separate them you might need to group by an object or entity ID.

That is more the other direction

I have done a few steps

Geometryfilter with surfaces

2Dforcer

Surfacefootprint

Then I get my wanted result

Thanks