El color en las piedras y los mosaicos de Rávena: nuevas imágenes de los monumentos antiguos a través de la fotogrametría no convencional de última generación. The colour of stones and mosaics in Ravenna: new images of ancient monuments using the latest generation of unconventional photogrammetry

This paper focuses on texture accuracy for a reliable simulation of construction materials present in some important historic monuments on the World Heritage List, dating back to Late Antiquity in Ravenna (Italy). A series of novel strategies will be explained in order to take advantage of automatic texturing solutions of 3D digital models created by Structure from Motion (SfM) applications. These monuments will be used as case studies to illustrate a shadow removal technique on Lambertian surfaces (stone, mortar, bricks, etc.) from apparent colour texture and a rapid approach for optic simulation of mosaic decoration. The latter consists of splitting a single apparent colour texture into a set of images whose purpose is to supply render engines more suitable shaders for representing coloured mosaic tiles in an optically reliable way.