Surface Appearance Estimation from Video Sequences Supervisor

Abstract

The realistic virtual reproduction of real world objects using Computer Graphicstechniques requires the accurate acquisition and reconstruction of both 3D geometryand surface appearance. The ability to play interactively with the reflectance,changing the view and the light(s) direction, is mandatory in most applications. Inmany cases, image synthesis should be based on real, sampled data: synthetic imagesshould comply with sampled images of the real artwork. Unfortunately, in severalapplication contexts, such as Cultural Heritage (CH), the reflectance acquisition canbe very challenging due to the type of object to acquire and the digitization conditions.Although several methods have been proposed for the acquisition of object reflectance,some intrinsic limitations still make reflectance acquisition a complex task for CH artworks:the use of specialized instruments (dome, special setup for camera and light source, etc.)that require to move the artwork from its usual location; the need of highly controlledacquisition environments, such as a dark room, which are difficult to be reproduced instandard environments (such as museums, historical buildings, outdoor locations, etc.);the difficulty to extend to objects of arbitrary shape and size; the high level of expertise requiredto assess the quality of the acquired surface appearance.This thesis proposes novel solutions for the acquisition and the estimation of thesurface appearance infixed and uncontrolled lighting conditions with several degreeof approximations (from a perceived near diffuse color to a SVBRDF), taking advantageof the main features thatdifferentiate a video sequences from an unorderedphotos collections: the temporal coherence; the data redundancy; the easy of theacquisition, which allows acquisition of many views of the object in a short time.Finally, Reflectance Transformation Imaging (RTI) is an example of widely usedtechnology for the acquisition of the surface appearance in the CHfield, even iflimited to single view Reflectance Fields of nearly at objects. In this context, thethesis addresses also two important issues in RTI usage: how to provide better andmore flexible virtual inspection capabilities with a set of operators that improve theperception of details, features and overall shape of the artwork; how to increase thepossibility to disseminate this data and to support remote visual inspection of bothscholar and ordinary public.