Suraj Musuvathy Elaine Cohen Joon-Kyung Seong James N. Damon Tracing ridges on B-Spline surfaces. 55-66 2009 Symposium on Solid and Physical Modeling http://doi.acm.org/10.1145/1629255.1629263 conf/sma/2009 db/conf/sma/spm2009.html#MusuvathyCSD09