Stereoplotting apparatus for correlating image points disposed along epipolar lines

Claim 2

In a device for measuring the correlation between points on stereo images in order to identify conjugate points on said stereo images, a maximum correlation being obtained between conjugate points, the improvement comprising: control means for limiting said correlating measurement to the measurement of the correlation between points lying substantially along corresponding epipolar lines on said two stereo images.

Claim 5

The device of claim 2 in which: said light directing means directs light to illuminate one point on each of said stereo images, and includes means for scanning said illuminated points across said two stereo images; and said control means include: means for controlling said scanning means to scan said illuminated points substantially along epipolar lines on said two stereo images; and means for controlling the transmission of information to said correlation measuring means to limit said correlation measurements to the measurement of the correlation between points on corresponding scanned lines of said two stereo images.

Claim 6

The device of claim 3 in which: said scan control means is adapted to scan said illuminated points substantially along epipolar lines of photographic stereo images of a scene taken from different vantage points at the same elevation and thereby scans the illuminated point on each stereo image along lines parallel to the projection of the line connecting the vantage points of each of said stereo images onto each of said stereo images.

Claim 7

The device of claim 4 in which: said scanning means comprises means for scanning a point light source along a reference plane; said holding means comprise means for holding photographic images having projection centers in positions relative to each other corresponding to the relative positions of photographic film during the formation of said images, said holding means including lens means disposed at the projection centers of each of said held stereo images for focusing Said point light source onto said two stereo images; and said scan control means scans said point source along lines in said reference plane parallel to the line connecting the projection centers of said two stereo images in order to thereby scan said illuminated points along epipolar lines on said two stereo images.

Claim 8

The device of claim 3 in which: said scan control means is adapted to scan said illuminated points substantially along epipolar lines of photographic stereo images of a scene taken from different vantage points at different elevations and thereby scans the illuminated point on said one stereo image along straight lines that project from the point at which a straight line connecting the vantage points of each stereo image intersects the plane of said one stereo image, and scans the illuminated point on said other stereo image along straight lines that project from the point at which a straight line connecting the vantage points of each stereo image intersects the plane of said other stereo image.

Claim 9

The device of claim 6 in which: said scanning means includes means for scanning a point source of light along a reference plane; said holding means comprise means for holding photographic images having projection centers in positions relative to each other corresponding to the relative positions of photographic film during the formation of said images, said holding means including a lens means disposed at the projection centers of each of said stereo images for focusing said light source onto said two stereo images and said scan control means scans said point light source along straight lines that project from the point at which a straight line connecting the projection centers of said two stereo images intersects said reference plane in order to thereby scan said illuminated points along epipolar lines of said two stereo images.

Claim 10

The device of claim 2 in which: said correlation measuring means includes means for measuring the correlation between the intensities of light modulated by a set of points along an epipolar line on one of said stereo images and the intensities of light modulated by a plurality of sets of points along a corresponding epipolar line on said other stereo image to identify the set of points along said epipolar line on said other stereo image having a maximum correlation with said set of points along said epipolar line on said one stereo image, a maximum correlation being obtained between sets of conjugate points.

Claim 11

The device of claim 8 in which: said control means includes means for controlling the transmission of information to said correlation measuring means, each set transmitted by said control means comprising a set of adjacent points lying substantially along an epipolar line on a stereo image, said plurality of sets of points on said other stereo image including at least two sets of points having a plurality of points in common, each of said two sets also including one point not included in the other of said two sets.

Claim 12

The device of claim 9 in which said control means include: means for recording the position of the first set of points along a first epipolar line on said one stereo image, and for recording the position of the set of points conjugate to said first set of points along a first epipolar line across one said other stereo image; and means for limiting the correlation measurement for a second set of points disposed at a position on a second epipolar line on said one stereo image corresponding to the position of said one set of points along said first epipolar line on said one stereo image, said correlation measurement being limited to a measurement of the correlation between said second set of points and the sets of points lying along only a portion of a second epipolar line on said other stereo image, said portion including a position along said second epipolar line on said other stereo image corresponding to the position of said set of conjugate points along said first ePipolar line on said other stereo image.

Claim 13

The device of claim 10 in which: said recording means includes means for recording the positions of said sets of points along said second epipolar lines on said stereo images; and said control means includes means for utilizing said recorded positions of said sets of points along said second epipolar lines to limit correlation measurements along third corresponding epipolar lines across said stereo images.

Claim 14

The device of claim 9 in which: said control means includes means for recording the position of a first set of points along an epipolar line on said one stereo image and for recording the position of the set of points conjugate to said first set of points along a corresponding epipolar line on said other stereo image; and said control means includes means for limiting the correlation measurement for a second set of points lying along said epipolar line to a measurement of the correlation between said second set of points and the sets of points lying along only a portion of said corresponding epipolar line, said portion including the position spaced a distance from said conjugate set of points equal to the spacing between said first and second sets of points on said one epipolar line.

Claim 15

The device of claim 12 in which: said recording means includes means for recording the positions of said second sets of points and the set of points conjugate to said second set of points; and said control means includes means for utilizing said recorded positions of said second set of points and said points conjugate to said second set to limit the correlation measurements for a third set of points lying along said epipolar line.

Claim 16

The device of claim 2 further including: calculating means for using the positions of points identified to be conjugate points to calculate the actual positions of a point represented by a pair of conjugate points on said two stereo images; and means for transmitting the locations of points identified to be conjugate points to said calculating means.

Claim 17

The device of claim 2 in which: said light directing means includes a high intensity light source for illuminating said two stereo images, the high intensity of said light source causing light modulated by each of said two stereo images to have a high signal to noise ratio, and thereby permitting highly accurate correlation measurements to be made.

Claim 18

The device of claim 15 in which said high intensity light source comprises a source of laser light.

Claim 19

The device of claim 2 in which: said light directing means directs light to illuminate one point on each of said stereo images, and includes means for scanning said illuminated points across said two images along lines forming an angle with at least a portion of epipolar lines on said two stereo images; and said control means includes means for limiting correlation measurements for a first point disposed along a first portion of an epipolar line on said one stereo image to a measurement of the correlation between said first point and points lying along a first scan line across said other stereo image, and for limiting correlation measurements for a second point disposed along a second portion of said epipolar line to a measurement of the correlation between said second point and points disposed along a second scan line across said other stereo image, all points conjugate to the points disposed along said epipolar line on said one stereo image being disposed along a corresponding epipolar line on said other stereo image, said first scan line being proximate said corresponding epipolar line along a first portion of said other stereo image, and said second scan line being proximate said corresponding epipolar line along a second portion of said other stereo image.