Abstract: An improvement for the real-time computer generation of visual scenes based on an algorithm that reduces the processing of elevation data to simple repetitive accumulations and a compare operation to generate occult data using grid elevation data bases is disclosed. The improvement reduces the size of the on-line, high speed, random access, data base memory required in image generation from grid data bases and reduces image generation time. The grid data base is divided into an array of data blocks. The data blocks are sequentially transferred to on-line ping-pong buffer memories (14), and each data block is processed through to final display by a view ray processor (16). The order of block selection is such that the sweep data remains continuous. When a sweep leaves a block, exit processing parameters are stored in a sweep horizon memory (18) as sweep parameters.

Abstract: An improvement for the real-time computer generation of visual scenes based on an algorithm that reduces the processing of elevation data to simple repetitive accumulations and a compare operation to generate occult data using grid elevation data bases is disclosed. The improvement adds three dimensional texture to close approach scenes to provide visual cues to the observer. The texture data is derived from the grid elevation data base itself and includes delta elevation and delta color values. The delta elevation values are added to the interpolated elevations computed by the image generator and the delta color values modulate the interpolated colors computed by the image generator. Since the texture data base is derived from the grid data base itself, the texture data base is already on-line thereby simplifying the memory and computational requirements of the computer image generator.

Abstract: A technique for the real-time computer generation of visual scenes of rolling terrain and sea waves is based on a view ray approach wherein an azimuth sweep is defined and an image profile is generated by incrementing range steps from the view point but employs a data base which is an on-line math model consisting of a summation of cosine functions rather than a grid data base. Math models are generated separately for both land and sea elevation posts for the scene to be generated. A horizontal field of view is defined as a predetermined number of increments between sweeps perpendicular to a boresight from a view point, and a vertical field of view is defined as a predetermined number of increments between view rays perpendicular to the boresight from the view point. The change in range is incremented along the boresight from the view point, and for each range increment, the view ray is stepped down by an increment corresponding to an incremental change in the tangent of the view angle.

Abstract: An algorithm for the real-time computer generation of visual scenes reduces the processing of elevation data to simple repetitive accumulations and a compare opertion to generate occult data using grid elevation data bases. The approach, when implemented as a software or firmware program, significantly speeds up scene generation time, and when implemented in hardware, significantly reduces the amount of hardware required. Accumulator (16) or counter (38) accumulates increments in tangent of the view angle, while accumulator (18) or counter (40) accumulates increments in range. Depending on the outcome of the compare operation of comparator (32), the accumulated tangent of the view angle or the accumulated range is used to compute in subtractor (26) the elevation of the view ray at each range increment of a sweep. This computed elevation is compared in comparator (32) with the corresponding elevation data for that point in the grid data base.

Abstract: Apparatus for processing data whereby a digital control signal is generated for effecting the presentation of a selected portion of a map image on a raster display. The data includes stored data words describing characteristics of line segments utilizable to construct the image. The line segments include line vectors representative of elongated features of the image and boundary vectors identifying boundaries between image areas of different brightness. Processing of the data is accomplished by means of two control loops. The first control loop performs selected macrosteps including arithmetic manipulations, on the data words to effect generation of the digital control signal. The second control loop effects selection of the macrosteps to be performed by the first loop and routes the data words within the generator in response to the instant data being processed by the generator.

Abstract: From stored environmental digital data giving coordinates of terrain features such as ridges and valleys and their associated brightness and color there is selected data on features lying in a vertical plane extending from a center which is the ground position of an elevated viewpoint. By data-processing means, the terrain elevation profile and the color profile for the vertical plane are generated. These profiles are then converted to a radar intensity profile by incrementing a ground sweep or to a perspective color profile by incrementing the view angle sweep. The process is repeated for each next adjacent sector until the entire desired azimuth range is covered. Presentation means is swept vertically, reproducing stored terrain profile patterns, with successive vertical sweeps lying side by side. Using equal angle increments for successive azimuth angles gives perspective representation for a spherical display.