In: Proceedings of the 20th International Conference on 3D Web Technology. ACM International Conference on 3D Web Technology (Web3D-15), 20th International Conference on 3D Web Technology, July 17-21, Heraklion, Crete, Greece, Pages 209-217, Web3D '15, ISBN 978-1-4503-3647-5, ACM, New York, NY, USA, 2015.