Simulation technique for generating a visual representation of an illuminated area

• US 4,177,579 A
• Filed: 03/24/1978
• Issued: 12/11/1979
• Est. Priority Date: 03/24/1978
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Singer PLC (Hayleys Plc)
• Inventors: Peters, David L., Trzeciak, John R., Schnitzer, Arthur P., Woycechowsky, Brain J.
• Primary Examiner(s): Grieb, William H.
• Application Number:
  US05/889,683
• Time in Patent Office: 627 Days
• Field of Search: 35/12 N, 35/10.2, 358/104, 340/27 NA
• US Class Current: 434/43
• CPC Class Codes: G09B 9/301 by computer-processed or -generated image
• CPC Class Codes: G09B 9/302 the image being transformed by computer processing, e.g. updating the image to correspond to the changing point of view

Abstract

A simulated view on a viewing surface of a raster scan television display of a changeable illuminated area located on a plane surface is provided. The source of illumination is a cone of light whose apex can be located at any distance from an eyepoint and the plane surface and whose conical surface intersects the plane surface creating the illuminated area. Electronic components determine when a line of sight from the eyepoint through the viewing surface intersects the illuminated area. For each line of sight intersection point lying within the illuminated area, a corresponding illumination is created on the viewing surface.

Claims

1. Apparatus for providing on a viewing surface of a raster scan television display a simulated view from an eyepoint of a changeable illuminated area located on a plane surface where the source of illumination is a cone of light, whose orientation can be varied, whose apex can be located at any distance from said eyepoint and said plane surface, and whose conical surface intersects said plane surface comprising:

a. means for generating first signals representative of changeable relative geometrical relationships between locations and orientations of said plane surface, said eyepoint, and said cone of light;

b. means for generating second signals representative of the position on said viewing surface of a line of sight from said eyepoint through said viewing surface to a plane surface intersection point;

c. a signal processor receiving and combining said first and second signals such that a third signal is generated representative of the location of the line of sight plane surface intersection point relative to a conic section generated by the intersection of the cone of light with the plane surface;

d. a signal comparator responsive to said third signal which determines whether said plane surface intersection point lies within, on, or outside said conic section; and

e. a video processor responsive to said signal comparator for modulation of said raster scan display, whereby the video modulation creates an illuminated area on the viewing surface corresponding to the plane surface intersection point when said point lies within or on the said conic section.

2. The apparatus of claim 1 wherein said means for generating said first signals comprises computer means, responsive to the position of the eyepoint relative to the cone of light and responsive to the position of the eyepoint relative to the plane surface, which generates said first signals such that the position of the eyepoint and the position of the cone of light can be defined relative to the plane surface.

3. The apparatus of claim 2 wherein said means for generating said second signals comprises:

a. means for generating signals representative of line of sight direction numbers which define the displayed line of sight relative to the said display viewing surface;

b. means for generating signals representative of display to ground direction cosines which allow the display viewing surface to be defined relative to the plane surface; and

c. arithmetic means for combining said signals representative of said display to ground direction cosines with said signals representative of said line of sight direction numbers for converting said line of sight direction numbers into ground axes direction numbers which are representative of the position on said viewing surface of a line of sight from said eyepoint through said viewing surface to a plane surface intersection point.

4. The apparatus of claim 3 wherein said signal comparator comprises first voltage comparison means such that when said third signal incident upon the comparator is within a first predetermined voltage range, which defines whether said plane surface intersection point is within or on said conic section, an output signal from said first voltage comparison means will be generated indicating that the intersection point is within or on said conic section.

5. The apparatus of claim 4 further comprising means to provide a signal to said video processor representative of the distance from the eyepoint to said plane surface intersection point so that the brightness of the illuminated area on the viewing surface corresponding to the plane surface intersection point can be regulated, whereby as the distance from the eyepoint to said plane surface intersection point increases, the illumination intensity decreases.

6. The apparatus of claim 4 further comprising a second signal comparator which comprises:

a. means for providing a signal representative of a position above the plane surface beyond which the line of sight no longer intersects the plane surface;

b. signal combining means receptive of one of said second signals which is representative of the line of sight position on said viewing surface normal to the plane surface, and receptive of said signal representative of a position above the plane surface, within which a difference signal is generated; and

c. a second voltage comparison means receiving said difference signal such that when the difference signal is within a second predetermined voltage range an output signal from said second voltage comparison means will be generated indicating that the line of sight will in fact intersect the plane surface.

7. The apparatus of claim 6 wherein said video processor comprises:

a. "and" gate means responsive to said signal output from said second voltage comparison means and said first voltage comparison means whereby an output signal will be generated from said gate means when both said first and second output signals from said voltage comparison means are incident upon the said gate means; and

b. video modulation means, responsive to said "and" gate means output signal, for modulating the CRT beam raster scan such that the instantaneous television display will present the illuminated area being viewed.

8. A method for providing on a viewing surface of a raster scan television display a simulated view from an eyepoint of a changeable illuminated area located on a plane surface where the source of illumination is a cone of light, whose orientation can be varied, whose apex can be located at any distance from said eyepoint and said plane surface, and whose conical surface intersects said plane surface comprising the steps of:

a. generating first signals representative of changeable relative geometrical relationships between locations and orientations of said plane surface, said eyepoint, and said cone of light;

b. generating second signals representative of the position on said viewing surface of a line of sight from said eyepoint through said viewing surface to a plane surface intersection point;

c. combining said first and second signals such that a third signal is generated representative of the line of sight plane surface intersection point relative to a conic section generated by the intersection of the cone of light with the plane surface;

d. determining whether said third signal indicates that the plane surface intersection point lies within, on, or outside said conic section; and

e. video processing the video signals of the raster scan display on the basis of said determination of step d such that an illuminated area on the viewing surface of the raster scan display is created corresponding to the plane surface intersection point within or on said conic section.

9. The method of claim 8 wherein the step of generating first signals comprises the steps of:

a. generating signals representative of line of sight direction numbers which define the displayed line of sight relative to the said display viewing surface;

b. generating signals representative of display to ground direction cosines which allow the display viewing surface to be defined relative to the plane surface; and

c. combining said signals representative of line of sight direction numbers and said signals representative of display to ground direction cosines for converting said line of sight direction numbers into ground axes direction numbers which are representative of the position on said viewing surface of a line of sight from said eyepoint through said viewing surface to a plane surface intersection point.

10. The method of claim 9 wherein the step of determining whether said third signal indicates that the plane surface intersection point lies within, on, or outside said conic section comprises the steps of:

a. determining whether said third signal is within a first predetermined voltage range which defines whether said plane surface intersection point is within, or on said conic section; and

b. generating an output signal indicating that the plane surface intersection point is in fact within or on said conical section when said third signal is within the said first predetermined voltage range.

11. The method of claim 10 further comprising the step of providing a signal for video processing representative of the distance from the eyepoint to said plane surface intersection point so that the brightness of the illuminated area on the viewing surface corresponding to the plane surface intersection point can be regulated whereby as the distance from the eyepoint to said plane surface intersection point increases, the illumination intensity will decrease.

12. The method of claim 10 further comprising the steps of:

a. providing a signal representative of a position above the plane surface beyond which the instantaneous line of sight no longer intersects the plane surface;

b. generating a signal representing the difference between one of said second signals, which is representative of the line of sight position on said viewing surface normal to the plane surface, and said signal representative of a position above the plane surface;

c. determining whether said difference signal is within a second predetermined voltage range which defines whether the line of sight will in fact intersect the plane surface; and

d. generating an output signal indicating that the line of sight intersects the plane surface when said difference signal is within said second predetermined voltage range.

13. The method of claim 12 wherein the step of video processing comprises the steps of:

a. applying said signal output from said first voltage comparison means and said signal output from said second voltage comparison means to "and" gate means such that an output signal will be generated from said gate means when both said first and second output signals from said voltage comparison means are incident upon said gate means; and

b. feeding said "and" gate output signal to video modulation means for modulating the CRT beam raster scan such that the television display will present the illuminated area being viewed.

14. A method for providing on a viewing surface of a raster scan television display a simulated view from an eyepoint of a conic section and surface within the section generated on a plane surface by the intersection of a cone with said plane surface, comprising the steps of:

a. defining the conic section located on the plane surface;

b. defining a line of sight from said eyepoint through the viewing surface of the raster scan television display to the plane surface;

c. determining the location of a line of sight intersection point on the plane surface;

d. comparing the line of sight intersection point with the defined conic section to determine whether the intersection point lies within, on, or outside the conic section; and

e. presenting upon the viewing surface a display corresponding to the conic section and surface within the section when the line of sight intersection points lie within or on the conic section.