Evans & Sutherland Computer Corporation

Other

Russell A Brown

Gary S Watkins

Glen A Eckart

Alan B Hayes

Bruce K Madsen

Thomas W Jensen

Primitive data in the form of defined lines for a computer graphics display is processed as by interpolating triangles, as during scan conversion, and by treating lines as triangle edges. An offset point is selected, e.g. offset perpendicularly from the line midpoint a distance of one-half the line length to define a triangle vertex along with the line endpoints. The resulting triangle is interpolated for example as with barycentric coordinates. Accordingly, the line may be interpolated, e.g. shaded, as though it were an edge of the defined triangle. For lines, sample points are coerced to lie on the triangle edge.

System for line interpolation for computer graphics displays

Barycentric coordinates are determined using data readily available in computer graphics systems and defining polygons in world space so as to interpolate such polygons with regard to pixels selected by scan conversion. The barycentric coordinates are employed to interpolate the polygons, for example to accomplish smooth shading or texture mapping. The process of the system involves defining primitive data (e.g. polygons) in a space not subject to nonlinear distortion (e.g. world space), transforming select primitive data to a space that is subject to nonlinear distortion, calculating in the space subject to nonlinear distortion (e.g. screen space) a set of areas (e.g. pixels) within a defined primitive (e.g. polygon) using data transformed to space subject to nonlinear distortion, transforming the set of areas to the space not subject to nonlinear distortion, determining at least one differential value (rate of change) of a variable for the primitive, calculating display data that is not subject to nonlinear distortion and using the differential to provide display data. For example, at a pixel, the rate of change in coordinate value (differential) is determined and utilized in texture mapping to facilitate the selection of levels of fuzziness with regard to picture detail for the pixel. Specifically, the differentials are in the coordinates of the texture du land dv.

System for polygon interpolation using instantaneous values in a variable

Image data is composed from primitives (polygons) to attain data for displays with the removal of hidden surfaces and smooth-appearing edges. Defined polygons are tested for priority in a determined field of vision by scan conversion to specify individual picture elements (pixels). Polygon contention for pixels is resolved by determining the edge of intersection between the planes of such polygons and testing the signs of certain values in accordance with predetermined criteria. Subpixel priority is treated for similar resolution to provide improved antialiased images.

Computer graphics priority system with antialiasing

A system is disclosed for subdividing parametric patches for use in a computer graphics system to develop images. The system utilizes initial data, provided as by an interactive user, to represent control points for an initial patch from which the system rapidly computes control points for subpatches using parallel processors. The disclosed system is recursive so that each level of subdivision leads to greater refinement of an initial patch. In one embodiment, the processors in the system compute multiple control points, the grouping of processors exploiting patch symmetrical properties.

Computer graphics, parametric patch parallel subdivision processor

A system utilizing computed tomography (CT) as for surgery. A CT scanner provides data representative of or slices taken through a body member. Display apparatus reveals the slices. A reference apparatus (frame) affixed to the body, operates in conjunction with the scanner and the display apparatus. The frame includes: structure for affixation to the body, holder means for guiding the therapeutic instrument, and structure for providing reference indications. The system further includes a data processing structure and control means for transforming data between frame coordinates and slice coordinates.

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Salt Lake City, UT, United States of America

Russell A Brown