Methods for compressing and decompressing data representing a digital three-dimensional object and information-recording medium for recording information containing said data

A method comprising causing a computer system to carry out compression of data representative of a three-dimensional object, said data comprising a mesh that is formed by a plurality of planar polygons that are contiguous with each other and a texture atlas that lists textures of all polygons in said mesh, each polygon comprising vertices that are joined by edges that delimit a face of said polygon and a texture that covers said face, wherein causing said computer system to carry out compression of said data comprises causing said computer to acquire said data and causing said computer to carry out the act of simplifying said mesh, wherein simplifying said mesh comprises deleting vertices from said mesh, thereby deleting polygons and creating, in place of said deleted polygons, new polygons that have faces that are broader than those of said polygons that have been deleted, wherein deleting said vertices from said mesh comprises identifying, as a function of a predetermined criterion, vertices to be deleted from said mesh, before deleting said identified vertices, identifying, in said mesh, first and second adjacent polygons that have different textures and that also have first and second shared vertices that are joined by a shared edge, providing a third vertex that occupies the same position in space as said first shared vertex in said second polygon, providing a fourth vertex that occupies the same position in space as said second shared vertex, creating a first edge between said first vertex and said third vertex, creating a second edge between said second vertex and said fourth vertex, creating an intermediate polygon that is interposed between said first and second polygons, deleting said identified vertices and edges that join said identified vertices to other vertices of said mesh, thereby deleting polygons comprising said identified vertices and said edges, creating new edges to join vertices that have not been deleted, thereby creating new polygons, and based at least in part on textures of said deleted polygons, creating new textures for said new polygons, wherein two polygons are adjacent if said polygons have a first shared vertex and a second shared vertex that are joined together by a shared edge, wherein said first edge has zero length, and wherein said second edge and said first edge have the same length, and wherein said intermediate polygon has a surface area of zero.