Abstract: A method and apparatus in a preferred embodiment for generating anti-aliased layered fog which is textured manipulated as if in a geocentric virtual environment to thereby show horizon depression at high altitudes. Hardware is provided such that layer model data and texture model data is combined to generate fogged pixel color.

Abstract: A method and an apparatus for improved pixel shading. The method of the present invention is based upon the notion of allowing multiple polygons to contribute to the net transmittance effect of a single pixel. This is accomplished by providing a new multi-sample data structure which can store visual attributes for each polygon, sorting all the transparent polygons in a front-to-back arrangement, processing the transparent polygon records and then the opaque polygon records by accumulating the net effect of the transmittance of all polygons being sampled in a pixel, and applying the color attributes to the net effect of transmittance, thereby decoupling color from the calculations for determining transmittance.

Abstract: An adaptive pixel multisampler generates pixel data for display by using sub-pixel areas to more broadly define the space of a pixel. A sub-pixel area is defined as having a "hole" within it that is occupied by a portion of each of the adjacent sub-pixel areas. This means that while the sub-pixel areas interlock, they do not overlap which would be wasteful of memory space. Accordingly, a pixel is newly defined as extending over a larger area than a standard contiguous pixel definition of the prior art allows. The larger pixel thus provides a wider sampler area which is then used as a means for generating a higher quality anti-aliased image on the display.

Abstract: Images for non-planar display systems are generated using polygon definitions that are pre-distorted using panel shear transforms. Initially, panel shear transforms are generated based on the configuration and orientation of a screen, a projector and a viewer. Polygons defined in model space are mapped to a two-dimensional space and then transformed to a panel space using the panel shear transforms. This transformation technique enables the use of standard two-dimensional rendering processes to scan-convert the polygons.

Abstract: An adaptive pixel multisampler generates pixel data for display using an interlocking sub-pixel sampling pattern and a frame buffer organized as a per-polygon, per-pixel heap. The interlocking sampling pattern provides the advantages of a multi-pixel shaped filter without pixel-to-pixel cross communication and without additional sub-pixels. The per-polygon, per-pixel heap allocates frame buffer memory so that each pixel will have one set of data stored in the frame buffer for every polygon that influences that pixel. This memory allocation scheme can significantly reduce frame buffer memory requirements. The polygon data is blended to properly handle processing of transparent polygons and polygon edges without the degradation of image quality found in conventional computer graphics systems.

Abstract: An image texturing system utilizes theme cells to generate terrain image data area-by-area for a dynamic terrain display. The system is effective in flight simulation apparatus, as for training pilots. A memory stores theme maps representing areas of specific terrains, e.g. terrains lying below a flight path. The theme maps are indexed on a square grid pattern and include a feature identification code (FIC) for each grid point to indicate terrain, e.g. forest, water, etc. A selection device controlled by an image generator selects a current theme map and dissects it cell-by-cell as defined by grid points to provide corner-referenced representations for each theme cell. A terrain storage device stores a library of terrain treatment pattern arrays that are derived, for example, from photo data of forest, ocean, or the like.

Abstract: Improved computer graphics system texture interpolation is provided using texture rules and planar texture interpolation. A texture rule is defined which characterizes texture variation within an area defined by a set of texels. The texture rule is used to select a texture plane which approximates the texture mapped to a pixel. This texture plane is used to generate a texture value for the pixel. In one embodiment, the texture rule identifies a triangle pair defined by four texels. One of these triangles is selected based on the position of the pixel relative to the texels. The pixel is then mapped to the plane defined by the selected triangle and the texture value for the pixel is calculated by interpolating the texture value at the location in the plane to which the pixel was mapped.

Abstract: A computer graphics system is defined using supersampling of multi-level pixel characteristic data. The system provides a detailed anti-aliased display of the texture on surfaces defined at oblique angles within the model space while providing simple real time controls to control the amount of extra processing required for the supersampling. A sampling path is defined within a projected pixel footprint on a textured surface defined in model space. These sample points are mapped to levels of detail and locations within a texture MIP map. The level of detail and supersampling locations are calculated for each pixel that the polygon influences. The sampled texture data is blended forming a single texture value for that pixel. This texture value is blended with other characteristics of the pixel to form the pixel data that is displayed on a display unit.

Abstract: To create a dynamic textured display, images of textured height fields (elevation samples arrayed on a rectangular coordinate grid, as to represent a terrain) are rendered, the system performing an initial pass that re-samples the height-field data into a radial form and a subsequent pass using the radial data to create textured, shaded picture elements (pixels) for an instantaneous field of view. Thus, texturing, shading, blending and scan conversion complete the pixel processing to drive a display unit. The system is particularly applicable to the generation of dynamic perspective images of terrain. The process provides pixel-limited textural resolution in the final image with effective antialiasing of internal and horizontal silhouette edges.

Abstract: A pendulum-actuated drawing instrument having at least two pendulums mechanically coupled with a scribing device by means of interconnected arms extending parallel to and above a support. The arms are universally pivottably connected and attached to the pendulums by means of nonextensible resilient rods.