MESHGRID-a compact, multiscalable and animation-friendly surface representation

  • Authors:
  • I. A. Salomie;A. Munteanu;A. Gavrilescu;G. Lafruit;P. Schelkens;R. Deklerck;J. Cornelis

  • Affiliations:
  • Dept. of Electron. & Inf. Process., Vrije Univ. Brussel, Brussels, Belgium;-;-;-;-;-;-

  • Venue:
  • IEEE Transactions on Circuits and Systems for Video Technology
  • Year:
  • 2004

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Abstract

MESHGRID is a novel, compact, multiscalable and animation-friendly surface representation method, which has been introduced in MPEG-4 . The MESHGRID representation attaches a description of the "global connectivity" between the vertices on the object's surface (i.e., the 3-D connectivity wireframe) to a regular 3-D grid of points (i.e., the reference grid). MESHGRID efficiently encodes the 3-D connectivity wireframe by using a new type of 3-D extension of Freeman chain-code. MESHGRID does not explicitly store the polygons of the surface, since the 3-D connectivity wireframe has particular connectivity properties allowing for the unambiguous derivation of the triangulation. The reference grid is a smooth vector field defined on a regular discrete 3-D space. This grid is efficiently compressed by using an embedded 3-D wavelet-based multiresolution intra-band coding algorithm. MESHGRID can be efficiently exploited for QoS since it allows for three types of scalability in both view-dependent and view-independent scenarios, including: 1) resolution scalability, i.e., the adaptation of the number of transmitted vertices; 2) shape precision, i.e., the adaptive reconstruction of the reference grid positions; and 3) vertex position scalability, i.e., the change of the precision of known vertex positions with respect to the reference grid. Furthermore, in addition to the classical vertex-based animation, MESHGRID also supports specific animation capabilities, such as: 1) rippling effects by changing the position of the vertices relative to corresponding reference grid points and 2) reshaping on a hierarchical basis of the regular reference grid and its attached vertices.