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Compression of 3D models in context of the MPEG-4 standard

Renk R., Jędrzejek C.

Image Processing & Communications

2002

Vol. 8, no 1

21-31

In this paper we analyze the current standardization situation for 3D geometry coding. In particular we concentrate on the topological surgery compression which is a basis for the MPEG-4 version 2 standard. In the method 3D surfaces represented by a triangular meshes are cut to form two trees: a spanning tree of vertices and a spanning tree of triangles. We show that for certain meshes with small number of vertices one can represent the mesh only by a triangle tree with some gain in compression. We have not demonstrated that such cut can be done for a general mesh nor that if this happens there is gain in compression, compared to the 2 trees representation.

Compact 3D model generation based on 2D views of human faces : application to face recognition

Karpouzis K., Votsis G., Tsapatsoulis N., Kollias S.

Machine Graphics and Vision

1998

Vol. 7, No. 1/2

75-85

A face recognition and synthetic-natural hybrid coding tool involving frontal and profile views is presented in this paper. The tool utilizes the above mentioned 2D images-upon which certian protuberant points are automatically detectrd- and adapts a generic 3D head model (polygon mesh) according to the predetermined information gained by the availble views. This mesh provides shape information which -combined with texture information- is important for the rebustness of a recognition system. the main advantage of the proposed approach is its ability to overcom constraints raised from arbitrary variations in scale, rotation and orientation, which are dominant deterioration factors in the identyfication task. Besides the face recognition aspect, applications which involve geometry transmistion, such as teleconferencing, can take advantage of the proposed algorithm's ability to parametrically describe a complex organic model, such as a human head. During the texture map creation process, issues related to the luminance differences and rotation varians between the avaible views, are successfully dealt with. Regarding the adaptation of the polygon topology of the 3D model, we apply a set of localized transformations, in order to preserve the continuity of the human head surface. Besides this, the problem of the minimum organic model representation required is addressed. The aspect under which this issue is verged upon, is thad of the solution of a trade-off problem between low computational complexity and high approximation quality.