General Electric Cgr S.a.

Octree Corporation

Olivier Lis

Guy Prevost

Michel Delcroix

Daniel Milon

Bruce Edwards

Donald Meagher

Process for representing views of an object

The problems of selection of objects having complex shapes and usually apprehended by a plurality of facets are solved by making use of curved surfaces, the equation of which is of the second degree. In a test calculation for checking whether a node of an octree decomposition does or does not belong to the surface thus defined, the terms of the second degree are replaced by a constant. It is shown that this approximation permits rapid determination of the complex shapes without having to perform the calculations corresponding to the second degree. The method also permits easy determination of the normal to the object for calculation of shadowing when it is employed for display.

Method for displaying a portion of the body

The 3D display device of the invention is based on an octree structure of data pertaining to an object to be displayed. This structure is memorized in a memory associated with a cache memory sending blocks of data on a bus to which a geometrical processor and an image-generating circuit are connected. The geometrical processor generates the visible part of another octree corresponding to a target universe which may be positioned in any way in relation to the object universe (a cube enclosing all the data to be represented).

Method for the 3D display of octree-encoded objects and device for the

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Versailles, France

Olivier Lis