These "RWTH Aachen"-models are optimized for a small number of polygons, low CPU usage and minimal storage space.
I combined a lot of the models to give a better overview.
About the RWTH:
RWTH Aachen University is a large university located in Aachen, Germany. "RWTH" is the abbreviation of Rheinisch-Westfälische Technische Hochschule which translates into "Rhenish-Westphalian Technical University". However, officially, "RWTH" remains untranslated. The university is part of the Deutsche Forschungsgemeinschaft, a society of Germany's leading research universities. http://www.rwth-aachen.de/go/id/hi/