Hi,In some cases, datasets with building footprints have some shapes which have reversed normals, so that after an initial extrude, the extrusion points down (into the ground).This can be prevented by checking the normal right on the shape, then reversing if needed :Lot -->
case convert(y, scope, world, pos, 0,1,0) - convert(y, scope,
world, pos, 0,0,0) < 0 :
reverseNormals
LotNormalUp
else:
LotNormalUp