Abstract: A three-dimensional model displaying method of displaying on a display screen a three-dimensional model expressed in a computer in the field of CAD or CAM. The quadrangular patches of the upper interface of a three-dimensional model is approximated with rectangular regions along the x-axis and y-axis of a two-dimensional coordinate system on the display screen. Accordingly, it is unnecessary to perform the operation of painting quadrangles irregular in configuration, and therefore the patch painting process can be achieved at high speed and with high accuracy.

Abstract: A method for determining the illumination of an illuminator at a selected point P in an image volume to be projected on an image screen surface by a computerized image generator, operates by: decomposing the illuminator into at least one of spherical, beam and cylindrical sources; determining a direction of incidence of the light from each source at point P in the image volume; determining the extent of the source and the attenuation of illumination with distance from that source; then determining a set of color light intensities at point P in the image volume due to the light from the particular source; and translating the incidence direction and color intensities from point P to a displayable incidence direction and a displayable set of color illumination intensities at a corresponding projection location on the image screen surface.

Abstract: A method for controlling a three dimensional cursor's position on a display with a two dimensional control device by generating a translation signal to the display when the control device was moved in such a way as to indicate that the user intended a translation of the cursor and generating an elevation signal to the display when the control device was moved in such a way as to indicate that the user intended an elevation of the cursor. Analysis of the single movement alone, however, being only the first step in truly interpreting the user's intentions, the present invention also includes steps for preventing certain types of control device movements from being interpreted incorrectly.

Abstract: A method and apparatus for determining a uniform step size with respect to pre-transformation derivative bounds for tessellation of a graphic primitive wherein the step size results in triangles which meet post-transformation thresholds. To maximize the efficiency of rendering curved surfaces while ensuring that the tessellation criteria is met, a maximum scale value for the non-linear transformation between device coordinate (DC) and lighting coordinate (LC) space is determined and utilized to translate the tessellation threshold in DC space to a tessellation threshold value in LC space. Information regarding the curved surface to be rendered is transformed to the LC space from the model coordinate (MC) space. The derivative bounds of the curved surface, and the tessellation threshold value are utilized to determine the uniform step size to tessellate triangles representative of the curved surface.

Abstract: An image processing system receives different types of image data with different number of bits per pixel, stores the image data into a memory, and applies given image processing steps to the image data stored therein. A control device is included in the image processing system. The control device determines the positions of pixels to be image processed, the number of pixels of one line, and the number of lines. For each line a least common multiple (LCM) of the number of bits of the pixel (B.sub.m) and the number of bits per access of the image data used in the image processing system (B.sub.0) is calculated, and the control device executes preset image processing programs under the determined conditions.

Abstract: Methods for texture mapping graphics primitives in a graphics pipeline architecture system. The methods utilize rectangular box filters to down-sample original texture maps thereby optimizing aliasing and blurring when graphics primitives have a two-dimensional texture mapped to a three-dimensional object. The methods of texture mapping graphics primitives in a frame buffer graphics system comprise the steps of determining an original texture map of two dimensions for a surface, storing the original texture map in the frame buffer, sampling the original texture map independently using an asymmetrical filter to construct multiple versions of a texture and to address textured pixels on a display in the frame buffer graphics systems, mapping the textured pixels to areas on the frame buffer, and displaying the textured graphics primitives on the display. A technique for addressing textured pixels stored in a rectangular texture (RIP) map is also described.

Abstract: In order to permit a user to predict the density, color balance, and contrast of an image to be printed on a hardcopy printing device, an image on a video color display device is provided with a uniform surround of controllable luminance and chrominance levels, the uniform surround being large enough in proportion to the image to mimic the viewing conditions of the final hardcopy. The presentation of user controls for image manipulation is integrated on the same color display device, with controllable brightness as compared to the controlled, uniform surround, to minimize disruption of the user's visual system as pertains to the perception of density, color balance and contrast. The user controls on the display device are faded away into the controlled, uniform surround for critical judgment of the video image. The user controls are subsequently restored to their original, controlled brightness. The rate at which the user controls fade in and fade out on the display device is controlled.