Juan Cao Yitian Zhao Ran Song 0001 Yingchun Zhang Local and global point sampling for structured point cloud simplification. 1843-1847 2012 FSKD https://doi.org/10.1109/FSKD.2012.6234227 conf/fskd/2012 db/conf/fskd/fskd2012.html#CaoZSZ12