Multisensor digital image generator

• US 4,017,985 A
• Filed: 08/22/1975
• Issued: 04/19/1977
• Est. Priority Date: 08/22/1975
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: General Electric Company
• Inventors: Heartz, Robert A.
• Primary Examiner(s): Tubbesing, T.H.
• Application Number:
  US05/607,063
• Time in Patent Office: 606 Days
• Field of Search: 35/10.4
• US Class Current: 434/2
• CPC Class Codes: G06T 15/10 Geometric effects
• CPC Class Codes: G09B 9/54 Simulation of radar G09B9/40 takes precedence

Abstract

From stored environmental digital data giving coordinates of terrain features such as ridges and valleys and their associated brightness and color there is selected data on features lying in a vertical plane extending from a center which is the ground position of an elevated viewpoint. By data-processing means, the terrain elevation profile and the color profile for the vertical plane are generated. These profiles are then converted to a radar intensity profile by incrementing a ground sweep or to a perspective color profile by incrementing the view angle sweep. The process is repeated for each next adjacent sector until the entire desired azimuth range is covered. Presentation means is swept vertically, reproducing stored terrain profile patterns, with successive vertical sweeps lying side by side. Using equal angle increments for successive azimuth angles gives perspective representation for a spherical display. Equal successive increments in tangent of the angle give exact perspective for a flat display such as a TV monitor. By including radar reflectivity in environmental data store, simulated radar PPI display is obtainable from same store, using somewhat similar sweep techniques. Visual and radar simulations may be placed to be viewed side by side, for training in comparison of radar return with visual scene of same terrain.

Claims

1. A simulator of a visual image, seen from an elevated viewpoint, of terrain described by a store comprising the three-dimensional coordinates of the endpoints of terrain lines defining the boundaries between terrain planes approximating the surfaces of the terrain and encoded descriptions of the optical characteristics of the surfaces, comprising:

a. means to define a series of sweeps, each in a vertical sweep plane including the elevated viewpoint and its ground position, at successive scan angles measured in a ground plane, the totality of such scans extending over the portion of the terrain to be simulated;

b. means to calculate the coordinates of the intersection with each sweep plane of each terrain line intersecting the sweep plane;

c. means to calculate the tangent of the angle between a reference line extending from the viewpoint in the sweep plane and a view line from the viewpoint to each said intersection;

d. means to compare the said tangent for each intersection with the tangents for the intersections preceding it in range in the sweep plane, measured from the ground position of the observation point, and to produce, responsively to the result of such comparison, an output signal indicating that the view line to the said intersection lies above the view line to any preceding intersection and the said intersection is therefore visible from the viewpoint;

e. means responsive to the said comparator means output signal to store for presentation the coordinates of each visible intersection and the encoded optical characteristics of the terrain planes bounded by it;

f. image formation means adapted to be deflected vertically by a vertical deflection signal and to be deflected horizontally by a horizontal deflection signal, and to produce at any point to which it is thereby deflected a measure of visibility of intensity controllable by an intensity signal;

g. means to receive the data stored for presentation and, responsively thereto, to apply to the image formation means

2. a horizontal deflection signal proportional to the tangent of the scan angle;

2. a vertical deflection signal varying continuously between a minimum and a maximum value during the existence of a given horizontal deflection signal;

3. an intensity signal produced by decoding the encoded optical characteristics stored for display, during the time when the vertical deflection signal lies between values proportional to the tangent for a first visible intersection and the tangent for the next visible intersection bounding the terrain plane having the said encoded optical characteristics, and the horizontal deflection signal has a value proportional to the tangent of the scan angle of the sweep plane in which are the said intersections.

3. A simulator of a visual image, seen from an elevated viewpoint, of terrain described by a store comprising the three-dimensional coordinates of the endpoints of terrain lines defining the boundaries between terrain planes approximating the surface of the terrain and encoded descriptions of the optical characteristics of the surfaces, comprising:

a. means to calculate and store, for each plane in a plurality of vertical planes extending at various azimuth angles through the ground position of the viewpoint, the coordinates of those intersections of terrain lines with the plane which are visible from the viewpoint, and the encoded descriptions of the optical characteristics of the surfaces bounded by the said intersections;

b. means to receive the stored data and, responsively thereto, to display in a plurality of vertical lines each horizontally spaced proportionally to the tangent of the azimuth angle of a vertical plane, visible traces representative of the encoded optical characteristics bounded by two said adjacent intersections in the plane over a vertical distance, in the line, whose endpoints are displaced vertically proportionally to the tangents of the angle between a line from the viewpoint to the said intersections and a horizontal line.