Free-form Acquisition of Shape and Appearance

This report focuses on the acquisition of shape and appearance of real objects under static illumination without the need for an elaborate calibration process or an expensive setup. Emphasis is placed on ease of use and obtaining visually pleasing results. Using recent advances in matting techniques, an opacity hull of the object is computed from an un-calibrated sequence of photographs. User interaction is limited to drawing trimaps for a small subset of the recorded photographs. These trimaps indicate which parts of the photographs represent the object, background or unknown. From these trimaps the mattes of the photographs can be extracted, and subsequently a coarse intermediate opacity hull can be computed. The opacity hull is iteratively refined by computing a trimap, and thus a matte, for the remaining photographs using the already computed mattes and the coarse intermediate opacity hull. We illustrate our method on a wide range of objects, ranging from ordinary objects and human heads to large outdoor statues.