Abstract: In an image browser for browsing a deck of hyperspectral images, the images of the deck are divided into square blocks each containing 25 pixels. The images are browsed by selecting foci of attention in selected images in sequence. Each time a focus of attention is selected, the image block containing that focus of attention is read out and displayed. Then if no new focus of attention has been selected by moving the focus of attention in the selected image or by changing the selected image, the image blocks surrounding the focus of attention in the selected image are read out and displayed in a spiral pattern until a new focus of attention is selected whereupon the process of read out and display starts again from the new focus of attention.

Abstract: In a system for segmenting a pixel based image, pixels containing image boundaries are identified. The image boundaries are then fattened by repeatedly adding fattening rows of pixels to the pixels containing boundaries to separate the remaining pixels into separate segments. The separate segments are then grown back to their original size before the boundaries were fattened. This operation has the effect of linking the boundaries together to separate the image into segments and to extend incomplete boundaries into complete boundaries around segments in the image.

Abstract: In a phase unwrapping and correction system, phase wrapped data is unwrapped with an unwrapping algorithm to obtain unwrapped image data. The unwrapped image data is further processed to correct the unwrapped image data by dividing the image represented by the unwrapped image data into regions defining boundaries corresponding to inconsistencies in the image data. The regions are then corrected by comparing them with one another and adjusting the multiples of 2.pi. assigned to each region to minimize discontinuities between the regions.

Abstract: In a method for generating a model of terrain, images of the terrain are generated at different angles. Matching points in the images are identified and from these matching points, the coefficients of a registration mapping equation are determined. A height term of the registration matching equation is corrected for scaling and shear into an elevation term in the coordinates of one of the images. The elevation is rotated into the coordinates of the ground plane of the terrain to provide a digital elevation model of the terrain. Interpolation is carried out through the digital elevation model to provide a three-dimensional model of the terrain. In a system for measuring the accuracy of a registration mapping equation, first and second images are generated from a digital elevation model. The registration mapping equation being tested is applied to the images to generate an estimated digital matching function which is compared with the actual registration matching function for the two images.

Abstract: A method and system for placing annotations of various sizes on a display without overlapping the annotations is described. Each annotation is represented by its rectangular bounding box along with an identifying line or arrow that joins the rectangle with the display object that is to be annotated. These rectangles and lines are stored in a list. When an additional annotation is to be placed on the display, it is tested at various positions to determine if there is overlap with the annotations that are already on the display. The tested positions are chosen by varying the length of the identifying line and the angle it forms with the horizontal. When a position is found that yields no overlap, the annotation is placed on the display and added to the list of positioned annotations. This approach is very fast due to the simplicity of the overlap tests, which consist of simple geometric operations.

Abstract: In a simulated synthetic aperture radar SAR, a terrain elevation model is provided. A phase component of the simulated SAR data is computed by determining a distance between incremental terrain points and a simulated SAR platform modulo the wavelength. The amplitude component is computed in the following manner. The terrain elevation model is rotated about a vertical axis to present terrain strips extending perpendicular to the assumed direction of travel of the SAR platform. Points distributed along the terrain strips are projected into an illumination plane perpendicular to the assumed SAR signal and into an image plane perpendicular to the illumination plane.

Abstract: In a method of recovering data representing terrain height from a synthetic aperture radar system the phase data is unwrapped by a Gauss-Seidel relaxation technique applied to a least squares differential equation in a multigrid algorithm. In the multigrid algorithm the problem represented by the least squares equation is transferred to successively coarser grids to more quickly remove the low frequency components of error. The resulting interim solutions determined on the coarser grids are then transferred successively back to the finer grids to converge on the finest grid of the grid array.

Abstract: A method and system for generating an anti-aliased image of a three dimensional surface is described. A point of view of the display screen is specified by an azimuth angle and an elevation angle with respect to the three-dimensional surface. The surface is defined as a two-dimensional array of height values. The projection of a point of the surface to the display plane is performed by applying a rotation based on the azimuth and elevation angles, followed by a parallel projection to the display plane so that, the columns of the surface project to the columns of the display screen. The points of the surface are projected in pairs, starting with the nearest points within a column and proceeding to the farthest points of the column. The grey-level shading (or color) values are accumulated in a one-dimensional array of floating-point variables that store the intensities of the pixels of a column of the display screen.

Abstract: Interactive graphical attitude maneuver planning computer system for planning satellite attitude maneuvers allows a user to immediately see where star trackers are pointing when the attitude and orbital position of a satellite are varied on the computer system. The computer system includes a graphics display on which the celestial sphere, centered at the satellite rather than the Earth, is projected. The horizontal axis of the display measures the Right Ascension angle, while the vertical axis measures the Declination angle. The display shows, in addition to stars, the region of the sky occluded by the Earth and interference regions around the moon, sun and planets, in which the star trackers should not point, and the fields of view of the star trackers. The attitude of the satellite is adjusted by means of graphical slider bars which vary the roll, pitch and yaw angle rotations.