Ok ok, it's all my fault, i now can export with no artefacts on n-gones, i was just doing things the wrong way. Sorry to have make you lose time on this, but at least it made me understand...

For modo, yes i can select the inverted polys in modo, but i have to select them "from behind", wich means turning around and inside the mesh again and again. But anyway this issue was solved by closing the mesh in MoI, so no more need to spent time on this either.

So, many thanks for your help, it all came from me and my poor technical skills, but you had me progressing. :)

Back to work now, buildings, buildings, houses, buildings...

Hi Gep, no problem, I'm glad you've got things working now!

But you may want to ask on the Luxology forum about some setting to make all polygons show up in the editor window instead of having back-facing ones being hidden in the display. There is likely some setting you can switch to make that happen and then you would no longer need to spin around to select those polygons, that would then make things easier.

- Michael

This option will help to solve your selection problem.