Abstract: A method and apparatus for performing a lens calibration procedure which is executed for each camera and lens pair. The calibration procedure is performed to determine the camera and lens nodal point offset and field of view, plus image offset in both the horizontal and vertical directions as a function of lens zoom and focus settings. The method includes the step of providing apparatus which enables the semi-automatic and rapid entry of data points representing lens zoom and focus setting information, thereby eliminating a source of human error. The general method includes the steps of creating a real environment and an identical virtual environment which is a copy of the real environment. The image from the virtual environment is superimposed on a monitor displaying the real environment. The camera's zoom and focus rings are incremented through a plurality of values by discrete steps. For each value, the virtual environment's settings are manipulated until the real and virtual images are identical.

Abstract: A patient-interactive method and apparatus for measuring eye refraction includes a display for producing, alternately, two spaced-apart light spots, and an aperture device for passing light from one spot through an aperture in one position, to travel to the eye, and for passing light from the other spot through an aperture in a second position, to travel to the eye. If the patient sees a single spot, the eye is properly refracting, but if he/she sees two spots, the eye is not properly refracting. Apparatus is provided to allow the patient to adjust the spacing of the light spots, and thus the angle that light enters the eye, until the patient views a single light spot. The amount of adjustment of the spacing of light spots is measured to thereby provide a measure of diopter correction necessary to correct the refraction error.

Abstract: A method and apparatus for providing an improved area of interest display system by providing a transition zone between a high resolution image being reflected onto and a low resolution image being projected onto a display screen. A combiner surface is provided in the form of a mirror having an all-reflective surface which transitions to an all-transmissive surface. The transition occurs in the form of pixels of highly reflective material which are disposed on the combiner surface using a dithering pattern generated from a modified error diffusion algorithm which minimizes undesired grouping of pixels.

Abstract: An adaptive pixel multisampler generates pixel data for display by using sub-pixel areas to more broadly define the space of a pixel. A sub-pixel area is defined as having a "hole" within it that is occupied by a portion of each of the adjacent sub-pixel areas. This means that while the sub-pixel areas interlock, they do not overlap which would be wasteful of memory space. Accordingly, a pixel is newly defined as extending over a larger area than a standard contiguous pixel definition of the prior art allows. The larger pixel thus provides a wider sampler area which is then used as a means for generating a higher quality anti-aliased image on the display.

Abstract: A method and apparatus for generating a viewport definition for a computer generated image using sensor information relating to a video camera's pan, tilt, zoom, and focus controls. The method generally comprises the steps of: (a) establishing reference points within an enclosed space which is to be used for recording images with the camera; (b) positioning the camera within the enclosed space relative to the reference points such that the camera position can be determined through triangulation with respect to the reference points; (c) developing position data through triangulation which identifies the camera position in a coordinate system relative to the reference points; (d) recording camera orientation data from sensors disposed to detect camera parameters defining the camera's pan, tilt, zoom, and focus settings; and (e) developing a database defining a viewport for the camera defined from a combination of the position data and the camera orientation data. Calculating the viewport (i.e.

Abstract: The present invention is directed to a simulation system for simulating virtual reality experiences such as for the sport of hang gliding or the like. The simulation system has a stereoscopic and collimated virtual image display, for providing pupil forming simulated images to a rider at a fixed point of reference relative to the stereoscopic display. In the disclosed embodiment, the simulation system comprises a mechanical support structure for suspending the rider in a harness so as to allow freedom of movement. The rider is suspended to face a visual display over a movable control bar coupled to the mechanical support structure. By maneuvering the control bar, riders may view the results of their actions as by a simulated display. The visual display is coupled to the control bar to receive electrical signals indicative of the movements initiated by the riders as they maneuver through a programmed environment.

Abstract: A method for rendering a shadow cast from an object illuminated by at least one light source onto at least another object on a graphical computer display. The preferred embodiment enables the rendering of accurate and realistic shadows in real-time, consequently providing a realistic view of three-dimensional objects in two dimensions. The shadow can also provide more visual clues than are otherwise available from ambient light sources. In this way, more visual information is provided to an observer.

Abstract: Images for non-planar display systems are generated using polygon definitions that are pre-distorted using panel shear transforms. Initially, panel shear transforms are generated based on the configuration and orientation of a screen, a projector and a viewer. Polygons defined in model space are mapped to a two-dimensional space and then transformed to a panel space using the panel shear transforms. This transformation technique enables the use of standard two-dimensional rendering processes to scan-convert the polygons.

Abstract: A system and method improves pixel update performance in computer graphics systems. Pixel sample coverage masks and data record memory locations are assigned to each pixel. The data record memory locations store pixel sample data for one or more pixel samples. A coverage mask is associated with each data record and contains mask bits which identify the pixel samples that are assigned the data contained in the data record memory location. In another embodiment, the pixels are also assigned versions which are compared with a current version. In response to the version comparison, predefined alternate pixel data or pixel data stored in a frame buffer is blended with new pixel data. The blended pixel data is written to the frame buffer from which it is retrieved and displayed by a display device. In another embodiment, pixel data memory is dynamically allocated to reduce the dedicated memory requirements while still providing high quality images.

Abstract: In a multiple-projector concave-screen display system, spacial alignment of images on the screen, is enabled by designating calibration points with retro-reflective dots and illumination markers. The manufacture of the screen involves locating calibration points and depositing the dots with a tool utilizing a rotary mechanism for loading and applying the dots from solenoid actuated pod units. Areas for retro-reflective dots, versus illumination markers, are defined on the basis of reflectance angles between vectors to the screen from a projector and from the screen to a viewer.

Abstract: A geometric processor provides object primitives, as triangles, in graphic display image space to support a dynamic display. The image space is defined by pixels, in turn specified in arrays as spans. In a multi-level scanning operation, primitives are scanned at a first level to locate lapped spans that are lapped by primitives. At a second level, spans are scanned to process pixels that are lapped by primitives. An alternative embodiment discloses three-level scanning in association with parallel pixel processing. Concurrent texturing structure operates along with cache memories.

Abstract: An adaptive pixel multisampler generates pixel data for display using an interlocking sub-pixel sampling pattern and a frame buffer organized as a per-polygon, per-pixel heap. The interlocking sampling pattern provides the advantages of a multi-pixel shaped filter without pixel-to-pixel cross communication and without additional sub-pixels. The per-polygon, per-pixel heap allocates frame buffer memory so that each pixel will have one set of data stored in the frame buffer for every polygon that influences that pixel. This memory allocation scheme can significantly reduce frame buffer memory requirements. The polygon data is blended to properly handle processing of transparent polygons and polygon edges without the degradation of image quality found in conventional computer graphics systems.

Abstract: An image texturing system utilizes theme cells to generate terrain image data area-by-area for a dynamic terrain display. The system is effective in flight simulation apparatus, as for training pilots. A memory stores theme maps representing areas of specific terrains, e.g. terrains lying below a flight path. The theme maps are indexed on a square grid pattern and include a feature identification code (FIC) for each grid point to indicate terrain, e.g. forest, water, etc. A selection device controlled by an image generator selects a current theme map and dissects it cell-by-cell as defined by grid points to provide corner-referenced representations for each theme cell. A terrain storage device stores a library of terrain treatment pattern arrays that are derived, for example, from photo data of forest, ocean, or the like.

Abstract: Improved computer graphics system texture interpolation is provided using texture rules and planar texture interpolation. A texture rule is defined which characterizes texture variation within an area defined by a set of texels. The texture rule is used to select a texture plane which approximates the texture mapped to a pixel. This texture plane is used to generate a texture value for the pixel. In one embodiment, the texture rule identifies a triangle pair defined by four texels. One of these triangles is selected based on the position of the pixel relative to the texels. The pixel is then mapped to the plane defined by the selected triangle and the texture value for the pixel is calculated by interpolating the texture value at the location in the plane to which the pixel was mapped.

Abstract: A dynamic terrain display is created from digitized grid post data as a height field, that is textured using maps embracing progressively larger areas with increasing remoteness from the viewpoint. A truncated pyramid is defined by map parts for each level that are maintained in active memory. The map parts or fragments are stored in rectangular configurations to be updated row-by-row or column-by-column, by overwriting obsolete data in a circular manner to reflect changes in the viewpoint. Levels of the map parts accordingly are paged independently of each other from database storage. Not all levels are required to have texture in that if a level is not available, a lower level can be employed. Theme cells also can be utilized.

Abstract: A computer graphics system is defined using supersampling of multi-level pixel characteristic data. The system provides a detailed anti-aliased display of the texture on surfaces defined at oblique angles within the model space while providing simple real time controls to control the amount of extra processing required for the supersampling. A sampling path is defined within a projected pixel footprint on a textured surface defined in model space. These sample points are mapped to levels of detail and locations within a texture MIP map. The level of detail and supersampling locations are calculated for each pixel that the polygon influences. The sampled texture data is blended forming a single texture value for that pixel. This texture value is blended with other characteristics of the pixel to form the pixel data that is displayed on a display unit.

Abstract: In a multiple-projector concave-screen display system, spacial alignment of images on the screen, is enabled by designating calibration points with retro-reflective dots and illumination markers. The manufacture of the screen involves locating calibration points and depositing the dots with a tool utilizing a rotary mechanism for loading and applying the dots from solenoid actuated pod units. Areas for retro-reflective dots, versus illumination markers, are defined on the basis of reflectance angles between vectors to the screen from a projector and from the screen to a viewer.

Abstract: A geometric processor provides object primitives, as triangles, in graphic display image space to support a dynamic display. The image space is defined by pixels, in turn specified in arrays as spans. In a multi-level scanning operation, primitives are scanned at a first level to locate lapped spans that are lapped by primitives. At a second level, spans are scanned to process pixels that are lapped by primitives. An alternative embodiment discloses three-level scanning in association with parallel pixel processing. Concurrent texturing structure operates along with cache memories.

Abstract: The present invention is directed to a simulation system for simulating virtual reality experiences such as for the sport of hang gliding or the like. The simulation system has a stereoscopic and collimated virtual image display, for providing pupil forming simulated images to a rider at a fixed point of reference relative to the stereoscopic display. In the disclosed embodiment, the simulation system comprises a mechanical support structure for suspending the rider in a harness so as to allow freedom of movement. The rider is suspended to face a visual display over a movable control bar coupled to the mechanical support structure. By maneuvering the control bar, riders may view the results of their actions as by a simulated display. The visual display is coupled to the control bar to receive electrical signals indicative of the movements initiated by the riders as they maneuver through a programmed environment.

Abstract: To create a dynamic textured display, images of textured height fields (elevation samples arrayed on a rectangular coordinate grid, as to represent a terrain) are rendered, the system performing an initial pass that re-samples the height-field data into a radial form and a subsequent pass using the radial data to create textured, shaded picture elements (pixels) for an instantaneous field of view. Thus, texturing, shading, blending and scan conversion complete the pixel processing to drive a display unit. The system is particularly applicable to the generation of dynamic perspective images of terrain. The process provides pixel-limited textural resolution in the final image with effective antialiasing of internal and horizontal silhouette edges.