VISUS, University of Stuttgart, Allmandring 19, Stuttgart, Germany. julian.heinrich@visus.uni-stuttgart.de|VISUS, University of Stuttgart, Allmandring 19, Stuttgart, Germany. julian.heinrich@visus.uni-stuttgart.de|VISUS, University of Stuttgart, Allmandring 19, Stuttgart, Germany. julian.heinrich@visus.uni-stuttgart.de|VISUS, University of Stuttgart, Allmandring 19, Stuttgart, Germany. julian.heinrich@visus.uni-stuttgart.de|VISUS, University of Stuttgart, Allmandring 19, Stuttgart, Germany. julian.heinrich@visus.uni-stuttgart.de|VISUS, University of Stuttgart, Allmandring 19, Stuttgart, Germany. julian.heinrich@visus.uni-stuttgart.de