Artiificially creating polygons

When you say “lower edge” are you meaning all edges that are in the lower half of the polygon?
Or all edges that face south?
Not sure if this is more just a geometry problem or if you are working with projected data of say building footprints.

Thanks for that, ​@liamfez . Yes, the lower half of the polygon. I wouldn't want just south of it as it's complex polygon. Although it is mostly linear (west to east), is does bend around in places. So, in places I’d want what is south of it, but in other places it would be what west of it, and so on. And in some tiny spots, what’s north of it (see bottom right corner). This is the poly…

So, if I ended up with something like the below, that would be a suitable result…

The other idea is to create a doughnut polygon around it. I could ten split as required.

Okay I was originally thinking of a solution for a more simple shape, but now that I see the polygon in question I am thinking a BoundingBoxReplacer followed by a Clipper may do the trick. Then you would just need to identify the correct outside polygon. I will test that and see what I can come up with.

Thanks. I’ll try it.

Sorry for the delay.

I ended up using a BoundingBoxReplacer, an Intersector, and an AreaBuilder to get the desired example outcome. I also used an OffsetCurveGenerator on the centerline of the input feature (checking orientation first) to identify which of the built polygons was the lower/southern. I am attaching a partial template file with a couple variations, including the one I was initially working on for different geometries so that you can see a couple different approaches.

This may also help with the geometry issue from your other post (Intersector and TestFilter produces result, but no geometry | Community)