Abstract: An image processing method is disclosed for generating 3-D graphical model data representing the appearance of a number of points in a 3-D region from two or more 2-D images of the region, the method comprising the steps of a) calculating, for each point, at least one variance value representing the variation, between different ones of the 2-D images in the region of the position on the 2-D images at which the point would appear if it were visible in the images; b) calculating, for each point and using a predetermined rule, a merit value from the variance values, the merit value representing the probability that, if the point lay on a visible surface in the 3-D region, the calculated variance values would be obtained; and c) assigning appearance data to each point in accordance with the merit values and the appearances of the positions on the 2-D images where the point would appear if it were visible thereon. The model is to be rendered to produce images for graphics applications.

Abstract: A method of generating a two-dimensional (2-D) image of a transform of a three-dimensional (3-D) solid object involves sub-dividing a 3-D box defining viewing space into sub-boxes, generating test-cells in object space by performing an inverse transform on the sub-boxes and determining which of the test-cells intersect the object. Thus, the need to transform the object itself is avoided. A particular application of the method is the generation of 2-D perspective images of a 3-D solid object. A graphics processing system including means for performing the method is defined.

Abstract: A method of generating a spatial representation of a 3-D solid object, which includes component shapes, which can be defined by transforming constructive solid geometry primitives includes the steps of, setting up a structure, to define the object in terms of the primitives and transforms setting up a definition of a 3-D box in a world space and then sub-dividing the box into sub-boxes, generating test-cells in object space by performing on the sub-boxes the inverse of each transformation to be performed on the primitives to create the object and determining which of the test-cells intersect the object. Thus, the need to transform the object primitives is avoided. A particular application of the method is the generation of 2-D images of a 3-D solid object.

Abstract: A method for identifying a bounded area of a graphic display. The method uses the division of the display screen into nine areas then the central square is the correlation window. This window can be small, two or three pel width, or large if the application is seeking to identify a larger area. The point indicated by the operator is in the center of the correlation window. An object (bounded area) which intersects this square will register a bit. It can be seen that a bounded area will intersect the correlation window if either: (a) any part of the boundary actually passes through the window, or (b) any arbitrary point within the window is inside the area.

Abstract: A digital data display system in which the display device includes a plurality of random access stores into which character cell definitions are loaded from a remote central processing unit. A character cell may be a 9.times.16 picture element matrix and each is defined in the CPU according to the requirements of a display request received from a users application program. The system control services include a graphics manager and graphics routines which construct a character buffer and character cell definition table according to the picture to be displayed. A character cell definition that is required more than once in a picture is only included once in the definition table, the character buffer having the required number of pointers to the one definition. When the character buffer and character definition table have been constructed, they are transmitted to the display device using a data communication system. The system can be used for color or monochrome displays.

Abstract: A compression technique for a character graphics system in which character cell definition bit strings are transmitted from a central processing unit to a display unit. Each cell is divided into a number of slices and each slice into digits. A test is made on whether to compress on a comparison with an all zero slice, the previous slice or the previous slice but one, depending upon the number of digit mismatches that occur when the comparison occurs. Slices are then compressed by comparing each digit with the corresponding digit in the comparison slice and generating a single 0 bit if the digit matches and including a 1 bit and the whole digit if a mismatch occurs. The compression in the central processing unit and the decompression in the display unit is implemented in microcoded routines.