Hellmuth Stachel, born 1942, got his PhD and habilitation in geometry in Graz. 1978 full professor at the Mining University Leoben, 1980-2011 full professor of geometry at the Vienna University of Technology. Coauthor of several books on mathematics and computational geometry and of more than 120 articles on geometry. Georg Glaeser, born 1955, got his PhD and habilitation in geometry at the Vienna University of Technology. Since 1998 full professor of geometry at the University of Applied Arts Vienna. Author and coauthor of more than a dozen books on geometry, mathematics, computational geometry, computer graphics, and photography. Boris Odehnal, born 1973, got his PhD and habilitation in geometry at the Vienna University of Technology. 2011-2012 professor at the Dresden University of Technology, since 2012 lecturer of geometry at the University of Applied Arts Vienna. Author of several dozens of publications on geometry.