Martin Aigner Laureano González-Vega Bert Jüttler Maria Lucia Sampoli Computing Isophotes on Free-Form Surfaces Based on Support Function Approximation. 1-18 2009 IMA Conference on the Mathematics of Surfaces http://dx.doi.org/10.1007/978-3-642-03596-8_1 conf/ima-ms/2009 db/conf/ima-ms/ima-ms2009.html#AignerGJS09