Francisco Morán Burgos

Automatic video to point cloud registration in a structure-from-motion framework

In Structure-from-Motion (SfM) applications, the capability of integrating new visual information into existing 3D models is an important need. In particular, video streams could bring significant advantages, since they provide dense and redundant information, even if normally only relative to a limited portion of the scene. In this work we propose a fast technique to reliably integrate local but dense information from videos into existing global but sparse 3D models. We show how to extract from the video data local 3D information that can be easily processed allowing incremental growing, refinement, and update of the existing 3D models. The proposed technique has been tested against two state-of-the-art SfM algorithms, showing significant improvements in terms of computational time and final point cloud density.

MPEG 3D Graphics Representation

The Tri-Dimensional Graphics (3DG) information coding tools of MPEG-4 are mostly contained in MPEG-4 Part 16, “Animation Framework eXtension (AFX)”, and focus on three important requirements for 3DG applications: compression, streamability and scalability. There are tools for the efficient representation and coding of both individual 3D objects and whole interactive scenes composed by several objects. Usually, the shape, appearance and animation of a 3D object are treated separately, so we devote different sections to each of those subjects, and we also devote another section to scene graph coding, in which we describe how to integrate MPEG-4’s 3DG compression tools with other (non MPEG-4-compliant) XML-based scene graph definitions. A final section on application examples gives hints on the flexibility provided by the 3DG toolset of MPEG-4.

Multi-resolution texture coding for multi-resolution 3D meshes

We present an innovative system to encode and transmit textured multi-resolution 3D meshes in a progressive way, with no need to send several texture images, one for each mesh LOD (Level Of Detail). All texture LODs are created from the finest one (associated to the finest mesh), but can be reconstructed progressively from the coarsest thanks to refinement images calculated in the encoding process, and transmitted only if needed. This allows us to adjust the LOD/quality of both 3D mesh and texture according to the rendering power of the device that will display them, and to the network capacity. Additionally, we achieve big savings in data transmission by avoiding altogether texture coordinates, which are generated automatically thanks to an unwrapping system agreed upon by both encoder and decoder