SYSTEM FOR COMPARING DETAIL IN A PAIR OF SIMILAR OBJECTS

• US 3,566,139 A
• Filed: 12/18/1967
• Issued: 02/23/1971
• Est. Priority Date: 12/18/1967
• Status: Expired due to Term

• Current Assignee: Donald C. Redpath, John W. Hardy
• Original Assignee: Donald C. Redpath, John W. Hardy
• Inventors: Hardy, John W., Redpath, Donald C.
• Application Number:
  US04/691,536
• Time in Patent Office: 1,163 Days
• US Class Current: 250/558
• CPC Class Codes: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying

Abstract

An image correlation system which produces vector error signals comprising error signal components corresponding to relative image detail misregistration along related nonparallel paths in each of the images being correlated. The vector error signals represent two-dimensional types of image detail misregistration and can control optical components to produce registration of the compared images. A pair of image storing electronic cameras having different rasters formed by nonintersecting scanning lines generate separate video signals for each compared image. The different scanning patterns permit a comprehensive comparison of the images while preventing the generation of undesirable video components caused by scanning line intersections.

Claims

1. A system for determining misregistration between homologous detail in a pair of objects and comprising signal generating means for producing one video signal representing variable detail along a given path in one of said objects and an additional video signal representing variable detail along a similar path in the other of said objects, a comparison circuit for comparing said one and said additional video signals and adapted to produce parallax error signals indIcating misregistration between common detail along said given and similar paths, and said comparison circuit comprising analyzer circuit means adapted to analyze said parallax error signals and to produce therefrom a vector error signal comprising error signal components representing relative detail misregistration between said objects along nonparallel paths in each of said objects.

2. A system according to claim 1 including adjustable means associated with said objects and controlled by said vector error signal to reduce the extent of detail misregistration represented thereby.

3. A system according to claim 1 wherein said vector error signal comprises a magnification error signal representing the average degree of relative detail misregistration between said objects in radial directions away from common points therein.

4. A system according to claim 1 wherein said vector error signal comprises a rotation error signal representing the average degree of relative image detail misregistration between said objects in uniform directions of rotation about common points therein.

5. A system according to claim 1 wherein said nonparallel paths terminate on Cartesian coordinate axes in each of said objects.

6. A system according to claim 5 wherein said axes are rectilinear and said nonparallel paths in each of said objects comprise paths that meet said axes so as to form obtuse angles with the portions of said axes that extend toward the origin of said coordinates.

7. A system according to claim 6 wherein said vector error signal comprises a skew error signal representing the average degree and sense of relative detail misregistration along said obtusely angled paths in directions away from the adjacent axes in one set of diagonal quadrants of the Cartesian system, and in directions toward the adjacent axes in the other set of diagonal quadrants thereof.

8. A system according to claim 6 wherein said vector error signal comprises a magnification error signal representing the average degree and sense of relative detail misregistration along si said obtusely angled paths in directions away from the adjacent axes in all quadrants of the Cartesian system.

9. A system according to claim 5 wherein said axes are rectilinear and said nonparallel paths in each of said objects comprise paths that meet said axes so as to form acute angles with the portions of said axes that extend toward the origin of said coordinates.

10. A system according to claim 9 wherein said vector error signal comprises a differential scale error signal representing the average degree and sense of relative detail misregistration along said acutely angled paths in directions toward the same coordinate axis in all quadrants of the Cartesian system.

11. A system according to claim 9 wherein said vector error signal comprises a rotation error signal representing the average degree and sense of relative detail misregistration in directions toward one coordinate axis along the acutely angled paths in one set of diagonal quadrants of the Cartesian system, and in directions toward the other coordinate axis along the acutely angled paths in the other set of diagonal quadrants thereof.

12. A system according to claim 5 wherein said axes are rectilinear and said analyzer circuit means is adapted to produce a plurality of vector error signals each comprising error signal components representing relative detail misregistration between said objects along nonparallel paths therein and said nonparallel paths comprise some paths that meet said axes a so as to form obtuse angles with the portions of said axes ta that extend toward the origin of said coordinates and other paths that meet said axes so as to form acute angles with the portions of said axes that extend toward the origin.

13. A system according to claim 12 wherein said vector error signals comprise a magnification error signal representing the average degree and sense of relative detail misregistration along said obtusely angled Paths in directions away from the adjacent axes in all quadrants of the Cartesian system, and a rotation error signal representing the average degree and sense of relative detail misregistration in directions toward one coordinate axis along the acutely angled paths in one set of diagonal quadrants of the Cartesian system, and in directions toward the other coordinate axis along the acutely angles paths in the other set of diagonal quadrants thereof.

14. A system according to claim 13 wherein said signal generating means comprise image producing means for producing optical images of said objects and said video signals represent image detail along paths in said optical images, said image producing means comprising an adjustable magnification lens means controlled by said magnification error signal to reduce the extent of image detail misregistration error signal to reduce the et extent of image detail misregistration in said optical images, said image producing means further comprising an image rotator means controlled by said rotation error signal to reduce the extent of image detail misregistration in said optical images.

15. A system according to claim 13 wherein said vector error signals further comprise a skew error signal representing the average degree and sense of relative detail misregistration along said obtusely angled paths in directions away from the adjacent axes in one set of diagonal quadrants of the Cartesian system, and in directions toward the adjacent axes in the other set of diagonal quadrants thereof;

and a differential scale error signal representing the average degree and sense of relative detail misregistration along said acutely angled paths in directions toward the same coordinate axis o in all quadrants of the Cartesian system.

16. A system according to claim 15 wherein said signal generating means comprises image producing means for producing optical images of said objects and said video signals represent image detail along paths in said optical images, said image producing means comprising adjustable optical means controlled by said vector error signals to reduce the extent of image detail misregistration in said optical images.

17. A system according to claim 1 wherein said signal generating means comprises camera tube means for scanning the detail along said given and similar paths and raster generator means for providing scanning beam df deflection signals for said camera adjustable means, sa controlled said analyzer circuit means is adapted to core correlate said parallax error signals with said deflection signals so as to produce said vector error signals.

18. A system according to claim 17 wherein said signal generating means comprises image producing means for producing optical images of said objects and said video signals represent image detail along paths in said optical images, said image producing means comprising adjustable optical means controlled by said vector error signal to reduce the extent of m image detail misregistration in said optical images.

19. A system according to claim 17 wherein said vector error signal comprises a magnification error signal representing the average degree of relative detail misregistration between said objects in radial directions away from common points therein.

20. A system according to claim 17 wherein said vector error signal comprises a rotation error signal representing the average degree of relative misregistration between said objects in uniform directions of rotation about common points therein.

21. A system according to claim 17 wherein said nonparallel paths terminate on Cartesian coordinate axes in each of said objects.

22. A system according to claim 21 wherein said axes are rectilinear and said nonparallel paths in each of said objects comprise paths that meet said axes so as to form obtuse angles with the portions of said axes that extend toward the origin of said coordinates.

23. A system according to claim 22 wherein said vector error signal coMprises a skew error signal representing the average degree and sense of relative detail misregistration along said obtusely angled paths in directions away from the adjacent axes in one set of diagonal quadrants of the Cartesian system, and in directions toward the adjacent axes in the other set of diagonal quadrants thereof.

24. A system according to claim 22 wherein said vector error signal comprises a magnification error signal representing the average degree and sense of relative detail misregistration along said obtusely angled paths in directions away from the adjacent axes in all quadrants of the Cartesian system.

25. A system according to claim 22 wherein said axes are rectilinear and said nonparallel paths in each of said objects comprise paths that meet said axes so as to form acute angles with the portions of said axes that extend toward the origin of said coordinates.

26. A system according to claim 25 wherein said vector error signal comprises a differential scale error signal representing the average degree and sense of relative detail misregistration along said acutely angled paths in directions toward the same coordinate axis in all quadrants of the Cartesian system.

27. A system according to claim 25 wherein said vector error signal comprises a rotation error signal representing the average degree and sense of relative image detail misregistration in directions toward one coordinate axis along the acutely angled paths in one set of diagonal quadrants of the Cartesian system, and in directions toward the other coordinate axis along the acutely angled paths in the other set of diagonal quadrants thereof.

28. A system according to claim 17 wherein said axes are rectilinear and said analyzer circuit means is adapted to produce a plurality of error signals each comprising error signal components representing relative detail misregistration between said objects along nonparallel paths therein and said nonparallel paths comprise some paths that meet said axes so as to form obtuse angles with the portions of said axes that extend toward the origin of said coordinates and other paths that meet said axes so as to form acute angles with the portions of said axes that extend toward the origin.

29. A system according to claim 28 wherein said vector error signals comprise a magnification error signal representing the average degree and sense of relative detail misregistration along said obtusely angled paths in directions away from the adjacent axes in all quadrants of the Cartesian system, and a rotation error signal representing the average degree and sense of relative detail misregistration in directions toward one coordinate axis along the acutely angled paths in one set of diagonal quadrants of the Cartesian system, and in directions toward the other coordinate axis along the acutely angled paths in the other set of diagonal quadrants thereof.

30. A system according to claim 29 wherein said signal generating means comprise image producing means for producing optical images of said objects and said video signals represent image detail along paths in said optical images, said image producing means comprising an adjustable magnification lens means controlled by said magnification error signal to reduce the extent of image detail misregistration in said optical images, said image producing means further comprising an image rotator means controlled by said rotation error signal to reduce the extent of image detail misregistration in said optical images.

31. A system according to claim 29 wherein said vector error signals further comprise a skew error signal representing the average degree and sense of relative detail misregistration along said obtusely angled paths in directions away from the adjacent axes in one set of diagonal quadrants of the Cartesian system, and in directions toward the adjacent axes in the other set of diagonal quadrants thereof;

and a differential scale error signal representing the average degree and sense of relative detail misregistration along said acutely angled paths in directions toward the same coordinate axis in all quadrants of the Cartesian system.

32. A system according to claim 31 wherein said signal generating means comprises image producing means for producing optical images of said objects and said video signals represent image detail along paths in said optical images, said image producing means comprising adjustable optical means controlled by said vector error signals to reduce the extent of image detail misregistration in said optical images.

33. An image comparison system comprising one optical system adapted to produce first and second identical optical images of one object, an additional optical system adapted to produce first and second identical optical images of an additional object, one pair of image storing electronic cameras adapted to receive said first and second optical images produced by said one optical system, an additional pair of image storing electronic cameras adapted to receive said first and second optical images produced by said additional optical system, said one pair of electronic cameras adapted to produce first and second video signals representing the radiation level in scanned portions of said first and second images produced by said one optical system, said additional pair of electronic cameras adapted to produce first and second video signals representing the radiation level in scanned portions of said first and second images produced by said additional optical system, and comparison circuit means for comparing said first video signals and producing one output signal indicative of nonuniformities in said scanned portions of said first optical images and comparing said second video signals and producing an additional output signal indicative of nonuniformities in said scanned portions of said second optical images.

34. An image comparison system according to claim 33 wherein said raster generator provides one scanning pattern for said electronic cameras receiving said first optical images and a different scanning pattern for said electronic cameras receiving said second optical images, and both said one and said different scanning patterns are formed by nonintersecting scanning lines.

35. An image comparison system according to claim 34 wherein said nonintersecting scanning lines are substantially parallel and the lines in said one pattern scan optical image portions which are substantially transversely related to the portions scanned by lines in said different pattern.

36. An image comparison system according to claim 35 wherein said one output signal produced by said comparison means indicates both the magnitude and sense of phase shift existing between said first video signals, and said additional output signal produced by said comparison means indicates both the magnitude and sense of phase shift existing between said second video signals.

37. An image comparison system according to claim 36 wherein said scanning lines in both said one and said different scanning pattern comprise diagonal scanning lines which scan in opposite directions.

38. An image comparison system according to claim 37 wherein said comparison means comprises primary correlator means adapted to invert the sense of said one output signal during periods wherein the scanning lines in said one scanning pattern scan in one of said opposite directions thereby providing one parallax signal and to invert the sense of said additional output signal during periods wherein the scanning lines in said different scanning pattern scan in one of said opposite directions thereby providing an additional parallax signal.

39. An image comparison system according to claim 38 wherein said comparison means comprises x parallax correlator means for combining said one and said additional parallax signals to provide an x parallax error signal, and a y parallax correlator means which inverts the sense of either said one or said additioNal parallax signals and combines the inverted signal with the other parallax signal to provide a y parallax error signal.

40. An image comparison system according to claim 38 wherein said comparison means comprises scale correlation means which inverts the sense of said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in either the first or third quadrant portions of a rectilinear Cartesian coordinate-type scan, blocks said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in the second and fourth quadrant portions thereof, inverts the sense of said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in either the second or fourth quadrant portions thereof, blocks said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in the first and third quadrant portions thereof, and combines the thereby altered said one and said additional parallax signals.

41. An image comparison system according to claim 40 wherein said comparison means comprises skew correlation means which inverts the sense of said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in either the second or fourth quadrant portions thereof, blocks said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in the first and third quadrant portions thereof, inverts the sense of said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in either the first or third quadrant portions thereof, blocks said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in the second and fourth quadrant portions thereof, and combines the thereby altered said one and said additional parallax signals.

42. An image comparison system according to claim 37 wherein said raster generator produces reference signals adapted to provide crossed diagonal raster patterns for said cameras, and including one blanking circuit means connected to said cameras receiving said first optical images and adapted to blank those portions of said reference signals which would produce scanning lines in one diagonal direction, and an additional blanking circuit means connected to said cameras receiving said second optical images and adapted to blank those portions of said reference signals which would produce scanning lines in the other diagonal direction.

43. An image comparison system according to claim 42 wherein said comparison means comprises primary correlator means adapted to invert the sense of said one output signal during periods wherein the scanning lines in said one scanning pattern scan in one of said opposite directions thereby providing one parallax signal, and to invert the sense of said additional output signal during periods wherein the scanning lines in said different scanning pattern scan in one of said opposite directions thereby providing an additional parallax signal.

44. An image comparison system according to claim 43 wherein said comparison means comprises x parallax correlator means for combining said one and said additional parallax signals to provide an x parallax error signal, and y parallax correlator means which inverts the sense of either said one or said additional parallax signals and combines the inverted signal with the other parallax signal to provide a y parallax error signal.

45. An image comparison system according to claim 43 wherein said comparison means comprises scale correlation means which inverts the sense of said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in either the first or third quadrant portions of a rectilinear Cartesian coordinate-type scan, blocKs said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in the second and fourth quadrant portions thereof, inverts the sense of said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in either the second or fourth quadrant portions thereof, blocks said additional parallax signals during periods wherein the scanning beams producing said different scanning pattern are in the first and third quadrant portions thereof, and combines the thereby altered said one and said additional parallax signals.

46. An image comparison system according to claim 45 wherein said comparison means comprises skew correlation means which inverts the sense of said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in either the second or fourth quadrant portions thereof, blocks said one parallax signal during periods wherein the scanning beams producing said one scanning pattern are in the first and third quadrant portions thereof, inverts the sense of said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in either the first or third quadrant portions thereof, blocks said additional parallax signal during periods wherein the scanning beams producing said different scanning pattern are in the second and fourth quadrant portions thereof, and combines the thereby altered said one and said additional parallax signals.

47. An image comparison system according to claim 36 wherein said one scanning pattern is formed by substantially horizontal scanning lines having a single common direction of scan and said additional scanning pattern is formed by substantially vertical scanning lines having a single common direction of scan.

48. An image comparison system according to claim 47 wherein said comparison means comprises x scale correlation means which inverts the sense of said one output signal only during periods wherein the scanning beams producing said one scanning pattern are in one of the horizontal halves thereof.

49. An image comparison system according to claim 47 wherein said comparison means comprises x skew correlator means which inverts the sense of said one output signal only during periods wherein the scanning beams producing said one scanning pattern are in one of the vertical halves thereof.

50. An image comparison system according to claim 47 wherein said comparison means comprises y scale correlator means which inverts the sense of said additional output signal only during periods wherein the scanning beams producing said different scanning pattern are in one of the vertical halves thereof.

51. An image comparison system according to claim 47 wherein said comparison means comprises y skew correlation means which inverts the sense of said additional output signal only during periods wherein the scanning beams producing said different scanning pattern are in one of the horizontal halves thereof.