Object-based irregular-grid volume rendering

Claim 1

A method to be carried out by a computer system for rendering data for display, the data representing a model space, comprising the steps of: associating individual points in the model space with individual vertices of an irregular grid cell enclosed by faces, each of the points having an associated luminosity value and an associated opacity value, whereby said step of associating preferably includes a step of determining an x, y and z coordinate of the point relative to the viewing plane and whereby said step of associating preferably includes a step of expressing the luminosity in terms of a plurality of colors; ordering faces of the grid cells, whereby said step of ordering preferably includes a step of ordering the faces by depth from the viewing plane; and processing individual faces for determining, for all viewing rays that project from pixels on a viewing plane and that intersect the face being processed, an amount of light arriving at the pixel, the amount of light being a function of both the luminosity and the opacity of a grid cell that lies adjacent to the face and through which the viewing ray passes, whereby said step of processing preferably is accomplished by processing the faces in order of increasing or decreasing depth from the viewing plane.

Claim 4

A method to be carried out by a computer system for rendering data for display, the data representing a model space, comprising the steps of: associating individual points in the model space with individual vertices of an irregular grid cell enclosed by faces, each of the points having an associated luminosity value and an associated opacity value; ordering faces of the grid cells by depth from a viewing plane; and processing, in order, individual faces for determining, for all viewing rays that project from pixels on the viewing plane and that intersect the face being processed, an amount of light arriving at the pixel, the amount of light (L) being a function of both the luminosity (l) and the opacity (o) of a grid cell that lies adjacent to the face and through which the viewing ray passes, wherein L← L X (1 - o) + l.

Claim 7

A method as set forth in any one of the claims 4 to 6, wherein λ is an accumulated light at a pixel, where τ is an accumulated transparency of processed grid cells, wherein the faces are ordered from closest to furthest from the viewing plane, and wherein λ is updated in accordance with and where τ is updated in accordance with where i is an estimate brightness of a grid cell and where i is an estimated total transparency of the grid cell.

Claim 8

A method as set forth in any one of the claims 4 to 7, wherein λ is an accumulated light at a pixel, wherein the faces are ordered from furthest to closest to the viewing plane, and wherein λ is updated in accordance with where i is an estimate brightness of a grid cell and where i is an estimated total transparency of the grid cell.

Claim 9

A method as set forth in any one of the claims 4 to 8, wherein the step of associating includes the steps of: maintaining a first list having entries including a three-dimensional position, a luminosity, and an opacity of points corresponding to vertices of the grid cells; maintaining a second list having entries including an identifier for each vertex of each grid cell; and establishing a pointer between each entry in the second list and an entry of the first list for specifying the position, luminosity and opacity of each vertex.