3D Video Fragments

Data Representation

The basic primitive of our framework is the 3D video fragment which is a point sample that can be dynamically generated, deleted and updated. As opposed to mesh based representations, 3D video fragments provide a one-to-one mapping between points and associated color and normal attributes avoiding interpolation and alignment artifacts. In particular the lack of local connectivity makes 3D video fragments much more efficient for updating, coarse-to-fine sampling, progressive streaming, and compression. Another benefit of retaining an underlying point based representation is graphics rendering.

We found the term 3D video fragment as three-dimensional analog for the 2D video fragment. The fragment in the classic computer graphics literature is defined as a display pixel - thus a 2D video fragment - with attached attributes such as depth or alpha value. Consequently, a 3D video fragment is a three-dimensional point sample with attached attributes (e.g. a position, a surface normal, a color) which is generated from a 2D video pixel or fragment.

The framework is generic in the sense that it works with any real-time 3D reconstruction method which extracts depth from images. Thus it is quite complementary to model or scene reconstruction methods using volumetric (e.g. space carving, voxel coloring), polygonal (e.g. polygonal visual hulls) or image-based (e.g. image-based visual hulls) approaches. Therefore, the framework can be used as a nice abstraction of the free-viewpoint video representation and its streaming from 3D reconstruction.

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© SW, 2004
Last Update: 05.01.2004