Abstract: Image data is composed from primitives (polygons) to attain data for displays with the removal of hidden surfaces and smooth-appearing edges. Defined polygons are tested for priority in a determined field of vision by scan conversion to specify individual picture elements (pixels). Polygon contention for pixels is resolved by determining the edge of intersection between the planes of such polygons and testing the signs of certain values in accordance with predetermined criteria. Subpixel priority is treated for similar resolution to provide improved antialiased images.

Abstract: A line-filtering antialiasing apparatus for a computer graphics display, with a set of parallel pixel processors functioning independently in a line drawing system and with plotting apparatus assigning individual pixels to the processors so as to track to the line. An optimum number of sixteen processors filter proximity data based on the vertical distance from a pixel center to the line center for shading pixels to gray-scale intensity in an area of influence four pixels wide. Line terminations are extended and shaded at the termination area. Pixel values for individual lines are summed to develop a total display image.

Abstract: Methods and apparatus for rendering a spacial contour texture map onto a generally planar polygon for display on the screen of a video monitor in a computer graphic system includes a memory for storing spacial distance measures between the individual texels of the contour texture map and a boundary on the contour texture map as well as an indentifier flag to define whether the texel is on one side of the boundary or the other. The contour texture map is applied to a modeled polygon by computing the intersection of each direction vector extending from an eyepoint through the center of a selected pixel to the contour texture map in a map space coordinate system. The projected size of a pixel on the contour texture map is also computed. The distance between the intersection point of each direction vector and the boundary of the contour texture map is computed and is projected onto the pixel space, that is, the screen of the display monitor.

Abstract: A system is disclosed for the production of real-time, computer-generated images as for projection on a curvilinear surface as on the inside of a dome. A general-purpose computer provides data for visual images and supplies the data in an ordered format. Such data is processed first with regard to viewpoint and second with regard to channel operation. Specifically, viewpoint processing incorporates an object manager and a polygon manager. Channel processing includes a geometric processor and a display processor. The display processor drives a projector for illuminating a spherical surface with the desired images. The geometric processor incorporates several well known elements including a rotator, clippers, a slope calculator and polygon buffer. Additionally, the geometric processor incorporates a segmenter and mapper which replaces the traditional perspective divider to process the data so as to generate images for curvilinear projection.

Abstract: A system is disclosed for subdividing parametric patches for use in a computer graphics system to develop images. The system utilizes initial data, provided as by an interactive user, to represent control points for an initial patch from which the system rapidly computes control points for subpatches using parallel processors. The disclosed system is recursive so that each level of subdivision leads to greater refinement of an initial patch. In one embodiment, the processors in the system compute multiple control points, the grouping of processors exploiting patch symmetrical properties.

Abstract: A z-buffer technique of exhaustive sampling is disclosed for rendering general surfaces in a computer graphics system. The system avoids the need for surface normal calculations or the computation of surface intersections with either ray or plane. It employs a dense surface scan of the object, which produces sample points on the surface. The samples thus obtained are passed through viewing transformations and then sorted into a z-buffer. The z-buffer retains the nearest sample to the viewer for each pixel, recording its x, y and z co-ordinates in object space. The surface normal at each pixel is estimated by comparison of neighboring entries and the corresponding intensity value is computed according to a standard illumination model.As disclosed, the system is applicable to a wide variety of surface types, e.g. parametric, implicit and procedurally defined surfaces; and to a wide variety of display styles such as shadowing, texturing and hidden-line.

Abstract: A command language system is disclosed wherein memory stacks register specific definitions for generic names, which definitions are appropriately selected in timely response to a name, on the basis of stack arrangement. A structure is included for searching the stack in order and detecting the first definition for a name of current interest. Thus, the stack is used to define the order of the name searching. As a consequence, in the interpretation of command languages, the user is given control over the context in which the names are executed. Specifically, a command program wil behave according to the definitions of the commands in a current context. The system further includes structure for deleting definitions from the stack which have been used and for sensing the bottom of the stack as a function of control.

Abstract: A display system is disclosed utilizing a cathode ray display device utilizing three electron beams which are directed through a shadow mask to excite three-color phosphor dots, and which is incorporated in a system to alternately provide raster scan display signals and calligraphic display signals to obtain the benefits of both raster scan and calligraphic displays (dot or line drawings). A deflection unit is disclosed with the X and Y deflection coils each driven by two pairs of transistor circuits. The transistor circuits are controlled so that alternatively one transistor in each set passes current to provide bi-directional currents at desired levels to obtain specific beam displacement. A resistive element between individual deflection coils provides an indication of deflection current, which indication is processed by a differential amplifier to indicate displacement. In accordance with the instant position of the beam, a convergence unit is controlled to reflect spherical considerations.

Abstract: Apparatus for detecting loss of AC power supply for an electrical conductor and loss of current through the electrical conductor when the power supply is connected thereto comprises voltage responsive means operable to produce a voltage present signal when the power supply is connected to the electrical conductor and a predetermined voltage is present across the conductor and a voltage absent signal when the predetermined voltage is not present across the conductor, and current responsive means operable to produce a current present signal when a predetermined current is flowing through the conductor and a current absent signal when the predetermined current is not flowing through the conductor.

Abstract: After evacuating gas in advance from a bin, gas is injected from the bottom of the bin and stirs up particulate material to mix or homogenize the particulate material.

Abstract: The present invention discloses a rotary engine having a cylindrical stator with a plurality of radially arranged cylinders each having a piston, a shaft is rotatably mounted co-incident with the longitudinal stator axis, and an orbitor having a cylindrical interior encompasses the stator. Sequentially phased reciprocation of the pistons is transmitted to the orbitor which orbits about the shaft axis in a "polishing-cloth" motion without rotation or revolution of the orbitor. A gear mechanism converts the orbital motion of the orbitor to rotation of the shaft.