During terrain creation, we use shapefiles to mass-fill areas such as forests, scrubland, applying various filters to the poly-shape(s) to get variation inside the shapefile.

You have to create a planar polygon inside your mapframe using the poly-shape tool. It quite often returns an error stating:

"PolygonalArea::UpdateGeometry() - Skipped shape: the polygon is not simple. (unnamed)"

After this error pops up you can no longer interact with the polygon reliably.

It sometimes corrupts the poly-shape and TB will blissfully leave your shape outline there ignoring the fact it's supposed to be a poly-shape, it will be invisible until you select it with the selection tool, this forces you to remove the poly-shape and start over again.

The level of complexity of the poly-shape Terrain-Builder allows varies drastically to produce this error. This forces us to keep our shapes as simple as possible, dividing what would be a large area into lots and lots more polygons. With lots of deletion and re-drawing of polygons whenever this error pops up. {F27907}