Eric J. Griffith Michal Koutek Frits H. Post Fast normal vector compression with bounded error. 263-272 2007 conf/sgp/2007 Symposium on Geometry Processing https://doi.org/10.2312/SGP/SGP07/263-272 http://dl.acm.org/citation.cfm?id=1282026 db/conf/sgp/sgp2007.html#GriffithKP07