Abstract: In a computer image generation system, the number of vertices which define each of a plurality of terrain-defining polygons is augmented in real time for providing finer detail and for effecting substantially continuous smooth level of detail (LOD) transition. Augmented vertices may have components that are statistically derived, in which case it is not necessary to store and/or predefine them. Alternatively, some vertex components may have predetermined values derived from mapping data or from other deterministic sources and may be stored in compact form. Processing polygons, typically triangles defined by selected ones of the sum of the augmented vertices and the original vertices, may be used for displaying the finer detail. Statistically derived finer detail is especially suited for providing non-specific detail to features such as terrain, while deterministic data allows highly accurate representations of specific `real world` locations.

Abstract: A method for distortion correction of computer-generated textured images maps vertices and texture coefficients from viewer space to projector space, so that environmental objects are pre-distorted upon the projection raster in order to appear in their proper form and perspective when the raster is projected onto a curved surface in viewer space, and viewed therefrom. Distortion correction is carried out by utilizing a piecewise-linear approximation for smoothly, continuously and closely approximating the required pre-curvature. The viewing space raster is subdivided into a number of triangles, within each of which a linear approximation is applied to the image mapping: the raster faces are first subdivided along the lines of a rectangular grid and the face fragments falling within each rectangle are then subdivided along the grid diagonal. This produces face fragments which are small enough so that a linear approximation provides an accurate transformation of each fragment.

Abstract: In a real-time computer-image generation system, processing resources for manipulating polygons that define objects are generally limited. This results in a trade-off with respect to the amount of detail to be displayed in an object versus the number and type of objects to be displayed. The value of a predetermined viewing criterion is used to determine when an object can be represented by a single polygon. The single polygon is rotatable about a predetermined number of axes for maintaining a predetermined relationship with respect to a view point. Since processing resources are saved by using a single polygon, additional objects and/or more detail may be included in a display.

Abstract: In a computer image generation system, the choice of a path for a vehicle model over a landscape is not restricted. Objects and features in an image to be displayed are defined by polygons. Plumb vectors, having a predetermined relationship with the vehicle model, are used to obtain samples of the terrain at the intersection between the vectors and polygons defining the ground in the vicinity of the vehicle model. The vectors may sample in advance of the vehicle model in the direction of motion or under the vehicle model. The polygons may be encoded with characteristics of the terrain they define so that appropriate noise cues can be generated from information extracted at the intersection of the plumb vectors and polygons. Predetermined ones of the sample points are interpolated for inferring the contour and slope of the terrain before interaction between the vehicle model and interpolated terrain is determined.