Patent
1994-11-08
1994-11-08
Zimmerman, Mark K.
395131, 395164, G06F 1572
Patent
active
053634756
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an image generator, and in particular to a computer image generator suitable for generating information in real time from which an image can be derived for display in for example a flight simulator.
Real time image generators for flight simulators are used to generate images which are presented to pilots who are positioned in a mock aircraft cockpit. In early systems, a visual environment was created using film or video images obtained from a servodriven camera that was maneuvered above a model of the terrain over which movement was to be simulated. These approaches were widely used but were found to be incapable of producing realistic scenes with true perspective from a wide range of eyepoints. In order to overcome these limitations, image generators producing computer generated imagery were introduced, the first commercially successful systems appearing in the early 1970s. Such systems are now used almost exclusively in flight simulator application, and are usually referred to as CIG (Computer Image Generation) systems.
In a CIG system, the intended viewer of the image produced by the system, i.e. the simulator pilot, looks out through an imaginary window into a three dimensional (3-D) world defined by information stored as geometrical and other characteristic attribute data. A line drawn from the eyepoint through the window intersects a point in the 3-D world. The color and intensity of that point must be "painted" on the window at the point of intersection of that line with the window. The displayed image is made up from a series of picture elements (pixels) each of which is of uniform color and intensity, the color and intensity of each pixel being a function of the position of the eyepoint relative to the 3-D world which the stored data represents. In a real time display where hundreds of thousands of pixels must be updated sufficiently quickly to avoid jumping of the image, it is necessary to perform many millions of calculations per second to maintain image fidelity. In most simulator systems producing a wide angle display the image is made up from three juxtaposed images each derived from a common database but generated by a respective processing channel. The computational load is thus shared between the three channels. We are concerned herein with the processes within a single channel only and therefore the interrelationship between associated channels will not be discussed.
A review of the problems confronted in real time CIG systems and various approaches to solving these problems is given in the publication "Computer Image Generation", edited by Bruce J. Schachter, published by John Wiley & Sons Inc. 1983, ISBN 0-471-87287-3. Brief details of common approaches adopted in known CIG systems are however given below to provide a context for the techniques described herein.
Generally, a simulator is designed to simulate the passage of an aircraft over a defined area of known terrain, for example the approaches to particular airports. In one known system, a main database is produced which is a 3-D model of that terrain, each point within the terrain having world space coordinates defining the position of that point relative to a predetermined origin. The entire 3-D surface is defined in terms of a series of features, e.g. polygons, having defined vertices, a defined color and a defined surface normal (a line drawn perpendicular to the plane of the polygon from one vertex). Further characteristics may be specified, e.g. surface texture (water, grass, etc.), the geometrical and other characteristics being referred to as the attributes of the feature.
The main database (referred to herein as the available database) may contain an area of the earth's surface far larger than that which can be seen from any one eyepoint position, for example an area 200 nautical miles square. The normal visibility range is generally considered to be less than 40 nautical miles. Thus not all the data within the main database has to be immediately available, and therefore data relating to an
REFERENCES:
patent: 4873515 (1989-10-01), Dickson et al.
patent: 4949280 (1990-08-01), Littlefield
patent: 5010515 (1991-04-01), Torborg, Jr.
Baker Stephen J.
Cowdrey Dennis A.
Olive Graham J.
Wood Karl J.
Rediffusion Simulation Limited
Zimmerman Mark K.
LandOfFree
Image generator for generating perspective views from data defin does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image generator for generating perspective views from data defin, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image generator for generating perspective views from data defin will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1789325