A virtual
terrain architecture and
computer program product for employing a geocentric coordinate
system, using a tessellated three-dimensional shape for representing a
celestial body, and mapping
terrain data to the tessellated three-dimensional shape is disclosed. In one embodiment, the methodology begins with a seed polyhedron such as an
ellipsoid model. The seed
ellipsoid is preferably composed of a plurality of triangle primitives. After selection of the seed
ellipsoid, the ellipsoid is subdivided using tessellation. Each
triangular element is subdivided into four sub-elements which are also triangular in shape. As the elements are further subdivided, the triangles of the ellipsoid model create a sphere that is representative of the earth or other
celestial body. Tessellation continues until a desired resolution is reached for each
triangular element. Once a sphere has been substantially formed,
terrain data is mapped to the triangular elements and the data is converted to
geocentric coordinates and stored in a
database. Each
triangular element is separately indexed according to the triangular elements name. By creating a geocentric representation, the earth's curvature and polar regions can be accurately represented. By using a tessellation process, tiling for the geocentric coordinate
system is achieved. Thus, the tiles can be paged as discrete elements.