|
Résumé :
|
Given a set of photographs of real objects or a scene, estimate the closest Three-dimensional geometry that specifically explains those photographs. In Computer Vision literature, this problem is known as Image-based Modelling or Multi-view Stereo (MVS) reconstruction. It is considered a hot research topic due to the huge technological advances of digital cameras, where these last became a cheap and reliable high resolution sensors. In fact, its application range from 3D mapping and navigations in robotics to video games and film making industry. Only recently however has this technique matured enough to be used in a natural uncontrolled environment. Meanwhile, Virtual Reality (VR) is witnessing a huge revolution due to the advances in display, sensing, and computing technology. In fact, the VR head mounted displays are mass produced, and a wide variety of people have access to this technology, consequently, experiences like virtual society, virtual travelling and tele-presence flourish. This class of applications however depends significantly on the visual fidelity of its contents. For instance, some applications capture a panoramic view of the remote environment, others build the virtual world inspired by real-life locations using classical modelling techniques, hence any false representation can render the experience inadequate due to the absence of immersion. Photogrammetry (also known as Multiview Stereo) on the other hand seems to be a natural answer to this problem. Nevertheless, achieving a high degree of visual fidelity becomes a challenge because these algorithms suffer from multiple major failure modes. This dissertation addresses the two major problem in multi-view stereo reconstruction related to virtual reality applications. First, we are focused on the interactivity. Such aspect puts the real-time as a high priority constraint. Thus, the reconstruction methods must be able to estimate the 3D shape of a static or dynamic object accurately in a matter of milliseconds. In fact, research proved that it is possible to use multiple cameras attached to cluster of networked computer, and model the 3D geometry of any rigid or static body in real-time. However, such setup is cost effective. Hence, we study the possibility of building a simpler system that run on a single machine, and we present a GPU accelerated image-based modelling system, the algorithm estimate and render on the fly all visible parts of a visual hull from a novel viewpoint without noticeable artifact. We carefully adapted our algorithm implementation to the recent off-the-shelf hardware. In the second part, we investigate the accuracy of the offline reconstructed objects. We aim for highly immersive virtual reality experiences. Therefore, it is a necessity for MVS to preform on large cluster of images such as community photo collection. These datasets not only they are large but also contain numerous settings in which photogrammetry fails. We propose a robust shading aware multi-view stereo method based on meta-heuristic optimization namely the Particle Swarm Optimization (PSO) to faithfully reconstruct textureless areas without any explicit regularization. Furthermore, to handle the various shading and stereo mismatch problems caused by a non-Lambertian surfaces, we present our robust matching/energy function which is a combination of two similarity measurements. Finally, qualitative and quantitative experiments are performed for multiple benchmarks, proving the effectiveness of our approach.
|
