Title:Automatic method for calculation of 3D chain-codes on contours of holes in three dimensional surfaces of free-form objects [Método Automático para el Cálculo de Códigos de Cadena 3D sobre Contornos de Huecos en Superficies Tridimensionales de Objetos de Forma Libre] / STSIVA 2012 - 17th Symposium of Image, Signal Processing, and Artificial Vision