Hello, I'm currently fighting with some Therion behavior. I'm not sure whether that is intentional or a bug. Sometimes it is necessary to use walls flagged "invisible", for example to close off passages where the walls are very far apart, or at complicated multi-way junctions. When generating a plan in kml output format, Therion appears to treat the "invisible" walls in the same manner as "visible" walls. When using standard GoogleEarth display you may not notice, but it becomes obvious when telling GoogleEarth not to fill the passages with color (via the properties dialog). Can the "invisible" walls be suppressed when generating kml ? Same happens when two scraps are connected to each other: at the place where the two scraps connect, i.e., at the scrap boundary, in plan - kml a wall is drawn (perpendicular) across the passage even if those passages are connected via "join". Cheers, Michael.