In: 19th International Conference on Computer Graphics, Visualization and Computer Vision 2011 (WSCG 2011) Pilsen. International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG-11), January 31 - February 3, Pilsen, Czech Republic, Pages 65-72, ISBN 978-80-86943-83-1, Union Agency, 2/2011.