Arno, Firstly - thankyou so much for developing this very useful tool. Last year I lost some source files in a Harddisk crash, which need changing and tweaking .. this is now possibe with the bgl libraries available. Thankyou so much! Now, to the question posed re Groundpolys I have done some preliminary testing, which seems ok ... but would value your thoughts .... Is there any reason why the x-file produced by ModelconverterX from an FSX model could not be used through MakeMDL2002 for Groundpoly creation. If this is possible, it would be a far easier way to extract x-files, for those of us that don't have the full FS2002 gamepack anymore. Also (feature request) ... is it possible to have ModelConverter add a "NoCrash" tag to model geometry, as a simple switch?