Showing papers by "Sabry F. El-Hakim published in 2008"

Turning images into 3-D models

Abstract: In this article developments and performance analysis of image matching for detailed surface reconstruction of heritage objects is discussed. Three dimensional image-based modeling of heritages is a very interesting topic with many possible applications. In this article we propose a multistage image-based modeling approach that requires only a limited amount of human interactivity and is capable of capturing the fine geometric details with similar accuracy as close-range active range sensors. It can also cope with wide baselines using several advancements over standard stereo matching techniques. Our approach is sequential, starting from a sparse basic segmented model created with a small number of interactively measured points. This model, specifically the equation of each surface, is then used as a guide to automatically add the fine details. The following three techniques are used, each where best suited, to retrieve the details: 1) for regularly shaped patches such as planes, cylinders, or quadrics, we apply a fast relative stereo matching technique. 2) For more complex or irregular segments with unknown shape, we use a global multi-image geometrically constrained technique. 3) For segments unsuited for stereo matching, we employ depth from shading (DFS). The goal is not the development of a fully automated procedure for 3D object reconstruction from image data or a sparse stereo approach, but we aim at the digital reconstruction of detailed and accurate surfaces from calibrated and oriented images for practical daily documentation and digital conservation of wide variety of heritage objects.

Digital reconstruction and 4D presentation through time

Abstract: Virtual time travel transforming the existing remains of a heritage site to its original condition has value for education and cultural understanding. However, digitally reconstructing objects which no longer exist is a challenge. Interaction and navigation within virtual 4D worlds (adding time to 3D worlds) is also problematic due to imprecise understanding of the time dimension. In this project we developed an approach to 3D modeling of sites that have undergone changes over the years. The method creates independent models from different types of data, such as frescoes, paintings, drawings, old photos, historic documents, and digitized remains. The models are assembled and integrated for a 4D interactive presentation. Several research issues have been addressed: (1) Modeling from frescoes and drawings with incorrect perspective, (2) modeling from paintings and old photos including fine geometric details from shading (3) coloring models from old photos and drawings to match existing elements, (4) creation of models by seamless and accurate integration of data obtained from independent sources, and (5) the creation of intuitive interactive presentations that link the models with other multimedia components and information related to the history of the site. We will describe contributions to these issues, including our own advanced model viewer [Dem ], and apply them to modeling heritage sites such as Venice which appeared in paintings by Canaletto, Bernardo Bellotto, and Francesco Guardi, and many 19th century photos. Canalettos paintings have been used to measure the subsidence of Venice [Camuffo and Sturaro 2003].