Abstract: A digital information storage and read-out system in which digital elevation and cultural terrain data is read from a magnetic tape in compressed form into an intermediate memory which operates as a speed buffer memory. The data in the intermediate memory is read out to a reconstruction processor in which the compressed data is reconstructed and applied to a scene memory. A navigation computer determines the instantaneous position of a vehicle with respect to the terrain and controls the reading of data into the scene memory in blocks with the vehicle position occupying a center of scene location. In order to provide a heading up display of the terrain, the data in the scene memory is raed out at an angle to its north-up storage orientation and interlaced scanning of pixel data in the scene memory improves resolution and enhances line display.

Abstract: A digital information storage and read-out system in which digital elevation and cultural terrain data is read from a magnetic tape in compressed form into an intermediate memory which operates as a speed buffer memory. The data in the intermediate memory is read out to a reconstruction processor in which the compressed data is reconstructed and applied to a scene memory. A nagivation computer determines the instantaneous position of a vehicle with respect to the terrain and controls the reading of data into the scene memory in blocks with the vehicle position occupying a center of scene location. In order to provide a heading up display of the terrain, the data in the scene memory is read out at an angle to its north-up storage orientation and interlaced scanning of pixel data in the scene memory improves resolution and enhances line display.

Abstract: A scheme for compressing and reconstructing multi-color high resolution navigation image data, such as aeronautical chart images provides an effective bit rate of one bit per pixel. Data representative of the image of a color aeronautical chart is sampled for a plurality of aerial grid points of the image (corresponding to pixels of the displays) each sample being digitized to provide an original color-representative matrix of data points, each resolved to some number of digital bits per basic color, per sample point. The color data is transformed into data representative of luminance (Y) and in-phase and guadrature chrominance (I, Q) components thereof. The Y, I, Q values are compressed using a clustering process that produces, for an aeronautical chart, sixteen clusters of combinations of colors and shades in the Y, I, Q domain.

Abstract: A signal processing mechanism for interpolating elevation data values between successive data points of a terrain map from which a simulated radar return image may be produced employs a signal processing operator in accordance with which input data signals representative of the elevations at successive data points on the terrain map are processed, to derive a continuous interpolated (terrain map) functional characteristic. Interpolated elevation data values at one or more points between successive ones of the original data points are calculated by employing elevation values for successive data points adjacent to those data points between which the one or more additional points of interest are located.

Abstract: A method and digital system for the compression and reconstruction of culal data for use with display systems, such as a system for producing a real time moving map display of terrain, provides a modified footprint/common boundary technique for data compression in which the footprint extends forward of the last point generated along a line in the direction of the line to that point. The particular scheme for compressed data reconstruction employs the storage of footprint data in such a manner that change in line direction information is automatically provided along with the necessary delta data information so that the direction of the line can be constantly updated as each point is generated. The compression of area cultural features involves a double compression of data based on a common boundary approach and the inner compression techniques of the modified footprint technique.

Abstract: In a dead reckoning navigation system a correlation scheme that operates in the frequency domain (using a discrete cosine transform (DCT) function) is implemented separately from the navigation system to determine a two-dimensional position error estimate. In this separate processing system measured terrain data is correlated (in the frequency domain) with reference elevation stored in map format (as by way of a digital map generator (DMG)). The results of this correlation are then employed to enhance the independently operated dead reckoning navigation system so that an accurate determination of geographic position may be obtained.

Abstract: A method and digital system for the compression and reconstruction of cultural data for use with display systems, such as a system for producing a real time moving map display of terrain, provides a modified footprint/common boundary technique for data compression in which the footprint extends forward of the last point generated along a line in the direction of the line to that point. The particular scheme for compressed data reconstruction employs the storage of footprint data in such a manner that change in line direction information is automatically provided along with the necessary delta data information so that the direction of the line can be constantly updated as each point is generated. The compression of area cultural features involves a double compression of data based on a common boundary approach and the linear compression techniques of the modified footprint technique.