Abstract: Image processing for extracting terrain features from an image formed of an array of pixels is disclosed. In a particular embodiment, each pixel in a neighborhood is averaged in a direction which is most homogeneous thereby preserving and smoothing edges of the image. Edge detection in orthogonal directions is applied for defining the magnitude and direction of edges at each pixel. After edges are defined each pixel is compared with pixels in a neighborhood for determining the probability that the pixel is on an edge and the angle at which such edge is disposed. Probable edges are reinforced and non-probable or non-edges are eliminated. Reinforced edges are thinned to a minimum of one pixel without eliminating its connectivity with any adjacent pixel on the edge. Components consisting of pixels of a similar kind which are connected are identified and uniquely labeled. At least two properties of each connected component are calculated including area and spread.

Abstract: A method and apparatus for topographic feature extraction by masking a video signal representation of an optical image using a two-dimension Walsh function is disclosed. The optical energy of an image is converted into a video signal. A Walsh function signal in accordance with a two-dimension Walsh is generated. The video signal is multiplied with the Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of the image. The method and apparatus can further include providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographic features. A selected topographical feature can be detected by comparing the Walsh transform coefficients signal with the selected topographical feature signals. The Walsh transform coefficients signal is unique to the selected topographical feature being detected.

Abstract: An image spectrum analyzer and method for cartographic feature extraction comprising an image, means for generating a Walsh function light pattern and for illuminating the image with the Walsh function light pattern to procuce a masked pattern, and means for receiving the masked pattern and for producing an electrical signal in accordance with same. A digital signal can be provided in accordance with the electrical signal, and a digital data processor under stored program control can provide a Walsh transform coefficient representative of the digital signal. More than one Walsh function light pattern can be generated by the apparatus and method of the present invention to produce more than one masked pattern, and representative Walsh coefficient. The Walsh coefficients can be used to perform cartographic feature extraction of the image.

Abstract: An automatic astroposition determination apparatus for performing measurets with improved precision and accuracy. A rectangular photosensor array is mounted in the focal plane of a theodolite and as the image of a star moves across the sensor array, a display of the image position and the time elapsed since the commencement of tracking is provided. Circuitry is provided to ensure that the leading edge of the star image on the array is tracked irrespective of how many photosensor elements the image overlies and irrespective of the direction of image transit on the array.