Abstract: Non-adjacent rows (i) in the visibility matrix (Msr) that have a large number of common elements are automatically detected (E7) and any such detected rows are permutated to put the lines detected as having a large number of common elements into sequence to form a modified visibility matrix (M?sr), and digital image coding is applied (E8) to the Boolean elements of the modified visibility matrix (M?sr).

Abstract: A method is provided for decoding a data stream representing an object with at least three dimensions, associated with a basic mesh including of an assembly of facets defined by an assembly of vertices and ridges, and with wavelet coefficients corresponding to the local modifications of the basic mesh, indexed each by a vertex of the basic mesh. For at least some wavelet coefficients of the data stream, the method includes the following steps: determining an orientation of an edge bearing the vertex indexing the wavelet coefficients, called an orientation of the wavelet coefficient; and determining, based on the orientation, information for locating in the basic mesh at least one child of the wavelet coefficient, distinct locating rules being associated with each orientation, so as to extract a data stream of at least some of the wavelet coefficients, associated each with locating information.

Abstract: In a geographical information system, a spatial environment is represented according to representation data with reference to geographical areas. The geographical information system comprises a server and a terminal connected via a communication network. The server stores the representation data according to the geographical areas. A selection of a plurality of geographical areas is made at the level of the terminal, as a function of a criterion relating to a load level of the terminal. A request is sent from the terminal to the server indicating the selected plurality of geographical areas. The terminal receives the representation data according to a continuous transmission protocol.

Abstract: A method of supervising the activity of a user in a virtual world comprising the steps of: (1) detecting at least one item of collision information between an observation line associated with the user and at least one first virtual object within the virtual world; and (2) determining at least one item of interaction information between the user and the first object on the basis of the collision information.

Abstract: The present invention sets out to combine a calculation of visibility from a viewpoint, with the selection of a level of detail for each of the nodes in a tree representing the geometry of the objects in a scene, so as increase the level of geometric detail of the visible objects and to reduce this level for all the obscured objects.

Abstract: A method is provided for decoding a data stream representing an object with at least three dimensions, associated with a basic mesh including of an assembly of facets defined by an assembly of vertices and ridges, and with wavelet coefficients corresponding to the local modifications of the basic mesh, indexed each by a vertex of the basic mesh. For at least some wavelet coefficients of the data stream, the method includes the following steps: determining an orientation of a ridge bearing the vertex indexing the wavelet coefficients, called an orientation of the wavelet coefficient; and determining, based on the orientation, information for locating in the basic mesh at least one child of the wavelet coefficient, distinct locating rules being associated with each orientation, so as to extract a data stream of at least some of the wavelet coefficients, associated each with a locating information.

Abstract: Non-adjacent rows (i) in the visibility matrix (Msr) that have a large number of common elements are automatically detected (E7) and any such detected rows are permutated to put the lines detected as having a large number of common elements into sequence to form a modified visibility matrix (M?sr), and digital image coding is applied (E8) to the Boolean elements of the modified visibility matrix (M?sr).

Abstract: The invention relates to a guiding process comprising the stages of: generating (106) an itinerary between starting and finishing points; generating guiding instructions including: the establishing (107) of several outstanding points close to a part of the itinerary taken from a database (2); the calculating (107) of an index representative of the visibility of outstanding points established from said part of the itinerary; the selecting (107) of at least one outstanding point according to the index of visibility; the generating (108) of guiding instructions associated with a selected outstanding point.