International Business Machines Corporation

Jaroslaw R Rossignac

Jai P Menon

Paul Borrel

James Sargent Lipscomb

David Alexander Epstein

Jeffrey W Wu

Robert Howard Wolfe

Michael Terrell Vanover

Nader Gharachorloo

Peter Daniel Kirchner

Mark Alan Einkauf

Keh-Shin Fu Cheng

Michael A O'Connor

Roger C Evans

Frederik W Jansen

Christos S Zoulas

Maarten J Van Emmerick

In a graphics processing and display system wherein the view point is controlled according to position and orientation of a view point reference with respect to a representation of the displayed graphics data determined by a view point reference coordinate sensing system comprising a source and a sensor, wherein the sensor has a fixed position and orientation with respect to said view point reference and the source has a fixed position and orientation with respect to the schematic representation, calibration of the system requires two ordered steps: view point reference-sensor calibration and source-representation calibration. View point reference-sensor calibration is performed by registering and processing four configurations of the sensor housing. Source-representation calibration is performed by storing and processing three positions of the sensor housing.

Precise calibration procedure for sensor-based view point control system

A graphics processing and display system includes a coordinate sensing system for determining position and orientation of a view point reference with respect to a schematic representation of at least one three-dimensional object; a view point controller for controlling a display view point according to the determined position and orientation of the view point reference with respect to the schematic representation; and a display processor for generating pixel data representing a two-dimensional rendering of the at least one three-dimensional object according to the graphics data and display view point, wherein the two-dimensional rendering is different from the schematic representation, and wherein the pixel data generated by the display processor is output for display on a display device. Advantageously, the system of the present invention is efficient and easier to use than prior art graphics processing and display systems because the user is provided the ability to control the display view point according to the position and orientation of the view point reference with respect to the schematic representation of the displayed object.

Schematic guided control of the view point of a graphics processing and

A computer graphics system includes a graphics processing engine for processing and displaying graphics data representing three-dimensional objects in a first portion of a display. A text processing engine displays text in a second portion of the display. Embedded in the text is a command or hotlink for controlling operation of the graphics processing engine. In response to user selection of first data displayed in the second portion of the display, a supervisory controller analyzes the first data to determine if the first data includes at least one hotlink command. Upon determining that the first data includes at least one hotlink command, the supervisory controller identifies the hotlink command included in the first data and controls operation of the graphics processing engine to perform at least one graphics function according to the hotlink command included in the first data. The graphics function may be associated with at least one of the three-dimensional objects, a three-dimensional markup, a predefined view point, or a predefined animation.

Hotlinks between an annotation window and graphics window for

A method for execution by a data processor that prepares an object for display. The method includes a step of processing a first model of the object so as to produce a simplified model thereof, the step of processing including the steps of (a) superimposing a first plurality of grid cells on the first model; for any one of the first plurality of grid cells containing more than one vertex of the first model, (b) combining the vertices into a first representative vertex; (c) generating a first simplified model that includes the first representative vertex or first representative vertices; and (d) storing the first simplified model for subsequent use. The method encompasses a number of criteria for use by the step of combining the vertices within a grid cell. These criteria include: (a) selecting a center of the grid cell as a position of the representative vertex; (b) selecting a position of a predetermined one of the vertices within the grid cell as a position of the representative vertex; (c) selecting an average position of the vertices as a position of the representative vertex; (d) selecting a position of a vertex that is nearest to the average position as a position of the representative vertex; and (e) selecting a position of a vertex that represents a locally extreme point within the grid cell as a position of the representative vertex.

Multi-resolution graphic representation employing at least one

Apparatus and method for generating displayable information expressive of a three dimensional solid object. The apparatus includes a processor (12,16) for expressing the object in a Constructive Solid Geometry representation thereof so as to be comprised of one or more primitive objects. The apparatus further includes a processor (18, 20) for repetitively evaluating the one or more primitive objects to determine displayable faces thereof. A depth interval buffer (20) is responsive to the operation of a scan conversion processor (18) for detecting when a predetermined number of repetitive evaluations occur without causing a change in the determination of a displayable face and for causing the operation of the evaluation processor to terminate. Toleranced depth tests are used to remove dangling faces or edges and to properly handle coincident faces. Pixel-centering is employed to improve the accuracy of depth tests and to identify pixels upon which a product projects. Shadowing is accomplished using a two-pass scan-conversion technique with an auxiliary shadow-buffer (ZS).

Direct display of CSG expression by use of depth buffers

A first method for producing wire-frame images of tessellated objects in real time utilizing existing hardware capabilities removes hidden lines by displaying the frame slightly away from the actual edges and toward the viewing direction to ensure the portion of the frame intended to be visible is not obscured by the visible faces and that the hidden portion of the frame is obscured by the visible faces. A second method allows for visible and hidden lines to be shown in unique line styles. This is done by first displaying all lines in the hidden line style while suppressing the faces. Then, the first method is performed and the lines that are visible lines are overwritten in another line style. A third method shows only visible silhouette and intersection edges. The visible silhouette edges are obtained by displaying the frame in thick lines behind the visible faces. Then, intersection edges are displayed in front of the faces so that only visible ones can be seen. A fourth method builds on the third by also showing hidden silhouette and intersection edges in a unique line style. Each object's silhouette edges are first obtained in hidden line style as if alone. Then, on all objects taken as one, all intersection edges are displayed and the third technique is performed in visible line style. The methods provide real time performance and can be implemented using standard graphics hardware. In addition, no edge-face adjacency information of objects is needed.

Method for selecting silhouette and visible edges in wire frame images

A system and method is provided for displaying trimmed surfaces on a computer graphics system. The present invention tessellates a three-dimensional surface into triangles and determines whether a trimming curve intersects any triangles. If an intersection occurs, a polygon trimming mask is formed by performing an exclusive OR operation and rendering the polygon into a mask plane. The XOR operation sets the bits in the mask plane corresponding to the trimming mask to logical 1. The rendering hardware then compares the bits in the mask plane with the bits in the frame buffer and draws those pixels which correspond to the bits set to 1 in the mask plane. Since, the trimming mask is a polygon the rendering hardware can perform shading, or lighting calculations using values for points which are contained on the tessellated triangle. In this manner, consistent lighting of a trimmed surface can be achieved. Additionally, the present invention provides for the formation of multiple trimming masks when multiple trimming curves intersect a tessellated triangle. The multiple trimming masks are sequentially XORed into the mask plane and the corresponding pixels are then drawn.

System and method for displaying trimmed surfaces using bitplane masking

A method for constructing the Minkowski sum and derivative morphological combinations of arbitray polyhedra uses operations supported in current CAD/CAM systems. The method has application to three-dimensional modeling of very large scale integrated (VLSI) circuits, their design and simulation of fabrication, and to automated mechanical assembly. The method also has application to n-dimensional modeling in robotics as well as other applications of CAD/CAM systems. In one aspect, an exact Minkowski sum of two polyhedra is obtained by a generalization of sweeping a face along an edge. More generally, according to a second aspect, the Minkowski sum of two polyhedra is computed as the union of linear translational sweeps enabled by the first aspect. The method implements techniques and formulas which greatly reduces the overall cost of the computation of Minkowski sums and, in particular, avoids computations involving non-transversal polyhedra. In a third aspect, the method reduces the difficulty of computing the Minkowski sum of a convex polyhedron and a general polyhedron by using simpler surrogate sets for the convex polyhedron.

Construction of Minkowski sums and derivatives morphological

A CSG solid modelling system 10 has a triple z-buffer architecture. For each pixel stored in a pixel memory 12 there are five storage entries grouped into five buffers including a front z-buffer (F) 16 which is employed to store the depths of a front face for a currently processed z-connected product, a back z-buffer (B) 18 which is employed to store the depths of a back face for the currently processed z-connected product and a final z-buffer (Z) 20 which stores the front faces of a displayed solid. Two other buffers are an intensity buffer (T) 22 for storing the intensities associated with the front face of the current z-connected product and a final intensity buffer (I) 24 for storing the intensities of the visible faces of the displayed solid. A bus 26 couples these various buffers together and to a processor 28 which may be a central processing unit or a peripheral processor. The system provides for a solid represented by any CSG tree to be represented as a union of z-connected products and that these z-connected products be expressed as intersections of z-connected sweeps. Furthermore it is shown that expressions of z-connected products in terms of sweeps are extracted directly from a CSG tree. Variations of the display methods may be used to detect interferences and differences between solids defined in CSG.

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Ossining, NY, United States of America

Jaroslaw R Rossignac