STEREO INSTRUMENT HAVING DIFFERENTIALLY VARIED LEFT AND RIGHT PARALLAX ERROR SIGNALS FOR PRODUCING SCANNING PATTERN DISPLACEMENTS

• US 3,752,580 A
• Filed: 10/20/1971
• Issued: 08/14/1973
• Est. Priority Date: 10/20/1971
• Status: Expired due to Term

• Current Assignee: John W. Hardy
• Original Assignee: John W. Hardy
• Inventors: Hardy, John W.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Godwin, Paul K.
• Application Number:
  US05/190,862
• Time in Patent Office: 664 Days
• Field of Search: 356/2 250/22SP
• US Class Current: 356/2
• CPC Class Codes: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying

Abstract

An automatic stereoplotting system employing both a high speed primary servo-system for inducing substantially instantaneous primary relative displacements between scanning patterns to eliminate detected parallax, and a more massive and slower reacting auxiliary servo system for inducing relative displacements between left and right stereo photographs being scanned. The auxiliary displacements of the photographs replace the initial primary displacements of the scanning patterns and a readout mechanism records measured elevations by continuously indicating the algebraic summations of both the primary and auxiliary displacements. A distribution circuit is provided for distributing the displacements of the scanning patterns between the scanning systems for the left and right stereo photographs so as to eliminate the parallax from each photograph in proportion to the actual image displacement on each photograph. This invention is an improvement on the Automatic Stereoplotting Apparatus described in U.S. Pat. No. 3,677,645, filed Mar. 1, 1970.

Claims

1. A stereo instrument for examining left and right stereo views of an object and for determining parallax in said left and right stereo views and comprising:

a. a left scanning system for scanning different points in said left stereo view and for producing a signal indicative of the image detail in each scanned point;

b. a right scanning system for scanning different points in said right stereo view and for producing a signal indicative of the image detail in each scanned point;

c. means for moving said left and right stereo views along an axis whereby different points in said left and right stereo views along said axis may be examined;

d. means for measuring the position of said left and right stereo views along said axis;

e. correlator means for correlating said signals from said left and right scanning systems to detect parallax between said left and right stereo views, and for producing a parallax error signal indicative of said parallax;

f. means, responsive to said measuring means, for distributing said parallax error signal into left and right parallax error signals having magnitudes that vary differentially depending upon the positions of said left and right stereo views along said axis, whereby the left and right parallax error signals are indicative of the amount of parallax present in each view;

g. means, responsive to said left parallax error signal, for displacing said left scanning system along said axis a distance dependent on the magnitude of said left error signal relative to The left stereo view and in a direction tending to reduce the parallax present in the left stereo view; and

h. means, responsive to said right parallax error signal, for displacing said right scanning system along said axis a distance dependent on the magnitude of said right error signal relative to the right stereo view and in a direction tending to reduce the parallax present in the right stereo view.

2. Apparatus as set forth in claim 1 and wherein:

a. said moving means includes a carriage which is movable along said axis and on which said left and right stereo views are mounted; and

b. said measuring means includes a potentiometer means mechanically coupled to said carriage so that the resistance of said potentiometer means changes as said carriage is moved along said axis.

3. Apparatus as set forth in claim 2 wherein said potentiometer means includes first and second potentiometers, said first and second potentiometers being mechanically coupled to said carriage means so that movement of said carriage means along said axis in a first direction will cause the resistance of said first potentiometer to increase and the resistance of said second potentiometer to decrease, and wherein movement of said carriage along said axis in a direction opposite said first direction will cause the resistance of said first potentiometer to decrease and the resistance of said second potentiometer to increase.

4. Apparatus as set forth in claim 3 wherein said stereo instrument includes:

a. a low speed servo system responsive to said parallax error signal for relatively displacing said left and right stereo views along said axis to reduce parallax between said left and right stereo views;

b. a high speed servo system, complementary to said low speed servo system, for responding quickly to said parallax error signals to reduce parallax between said left and right stereo views, said high speed servo system including said means for displacing said right scanning system and said means for displacing said left scanning system.

5. Apparatus as set forth in claim 1 wherein said stereo instrument includes:

a. a low speed servo system responsive to said parallax error signal for relatively displacing said left and right stereo views along said axis to reduce parallax between said left and right stereo views;

b. a high speed servo system, complementary to said low speed servo system, for responding quickly to said parallax error signals to reduce parallax between said left and right stereo views, said high speed servo system including said means for displacing said right scanning system and said means for displacing said left scanning system.

6. Apparatus as set forth in claim 5 wherein:

a. said moving means includes a carriage which is movable along said axis and on which said left and right stereo views are mounted; and

b. said measuring means includes a potentiometer means mechanically coupled to said carriage so that the resistance of said potentiometer means changes as said carriage is moved along said axis.

7. Apparatus as set forth in claim 6 wherein said potentiometer means includes first and second potentiometers, said first and second potentiometers being mechanically coupled to said carriage means so that movement of said carriage means along said axis in a first direction will cause the resistance of said first potentiometer to increase and the resistance of said second potentiometer to decrease, and wherein movement of said carriage along said axis in a direction opposite said first direction will cause the resistance of said first potentiometer to decrease and the resistance of said second potentiometer to increase.