Parallel line scanning system for stereomapping

• US 3,901,595 A
• Filed: 02/13/1974
• Issued: 08/26/1975
• Est. Priority Date: 02/13/1974
• Status: Expired due to Term

• Current Assignee: Arliss E. Whiteside, Gerald A. Brummn, Uuno V. Helava
• Original Assignee: Arliss E. Whiteside, Gerald A. Brummn, Uuno V. Helava
• Inventors: Helava, Uuno V., Whiteside, Arliss E., Brummn, Gerald A.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Evans, F. L.
• Application Number:
  US05/442,024
• Time in Patent Office: 559 Days
• Field of Search: 356/2 250/558
• US Class Current: 356/2
• CPC Class Codes: G01C 11/06 by comparison of two or more pictures of the same area

Abstract

A system for use in conjunction with a stereomapper for determining conjugate points on stereoscopically generated images along a plurality of parallel lines during each mechanical translation of the images across the area being mapped. The system operates in the digital domain and incorporates control logic, either hardware or software, for modifying the data to correct the geometrical distortions, for selecting the data to be correlated in accordance with the parallax data computed from the preceding correlation, for correlating the selected data, and for generating parallax data. The conversion of the image data to digital form and its attendant storage capabilities permits the data generation to proceed independent of the generation of parallax data. The use of the special purpose minicomputers for data shaping, correlation, and the computation of parallax data permits the data generated by scanning the many parallel lines to be converted to parallax data without exceeding the computation capacity of existing electronics. Further, the scanning of a plurality of parallel lines during each translation of the images reduces the number of translations required to scan the desired area on each image and significantly increases the speed at which the area may be mapped.

Claims

1. In an automatic stereomapper for making a map from a pair of stereoscopic images, said stereomapper having means for mechanically translating said stereoscopic images relative to said stereomapper along a series of parallel lines at predetermined intervals within the area of the stereoscopic images to be mapped, means scanning corresponding areas on both stereoscopic images for generating parallax data indicative of the displacement of corresponding imagery on the stereoscopic images, a control computer for converting the parallax data into information from which the map can be made and means for receiving the information for making the map, an improvement to the means for generating parallax data for generating parallax data about a plurality of parallel lines, disposed parallel to said mechanical translation during each of the translations comprising:

means for generating, during each mechanical translation of said stereoscopic images, blocks of digital data indicative of corresponding imagery on both stereoscopic images about a plurality of parallel lines disposed parallel to the direction of the translation;

means for temporarily storing said blocks of digital data in a predetermined sequence;

means receiving at least two blocks of digital data from said storage means, one block of data indicative of the imagery on one stereoscopic image and the other block of data indicative of the corresponding imagery on the other stereoscopic image for correlating the data in said at least two blocks of digital data in a plurality of shifted relationships to generate correlation data indicative of the correlation at each shifted relationship;

means receiving said correlation data for generating parallax data indicative of the shifted relationship between the data in said at least two blocks of digital data when said correlation data is indicative of maximum correlation; and

means receiving said parallax data for generating a data transfer signal transferring the next two data blocks to be correlated from the storage means to the correlation means and a parallax address modification signal to shift the data in one of the two blocks of digital data transferred to the correlation means to the shifted relationship having maximum correlation during the correlation of the two blocks of data just previously correlated.

2. The improvement of claim 1 wherein said means for generating blocks of digital data comprises:

means having a repetitious scan pattern for individually scanning corresponding areas on both stereoscopic images about said plurality of parallel lines with a point of light to generate light signals modulated by the imagery in each of the scanned corresponding areas;

detector means for converting said modulated light signals into analog electrical signals;

means associated with said means for scanning for generating digital address signals at predetermined intervals indicative of the position of said point of light during the scanning of said corresponding areas;

means responsive to said digital address signals for sAmpling said analog electrical signals to generate digital data indicative of the imagery on both stereoscopic images at said predetermined intervals; and

means temporarily storing the digital data generated during each scan of both stereoscopic images for forming individual blocks of image data indicative of the imagery on the individual stereoscopic images within each repetitive scan pattern.

3. The improvement of claim 2 wherein the control computer generates distortion signals indicative of known geometrical distortions in the stereoscopic images, said means for sampling further includes means responsive to said distortion signals for controlling the predetermined intervals at which said samples are taken to correct for the known geometrical distortions in the stereoscopic images.

4. The improvement of claim 3 wherein said means for scanning comprises:

two cathode ray tubes, each having an electron beam generating a point of light on the face of each tube;

means for individually focusing both of said points of light on the stereoscopic images, one point of light being focused on one stereoscopic image, and the other point of light being focused on a corresponding point on the other stereoscopic image; and

means for deflecting said electron beams to cause said points of light to scan corresponding areas respectively on each of said stereoscopic images.

5. The improvement of claim 3 wherein said means for scanning comprises:

a light source for generating a narrow beam of light;

means for dividing said narrow beam of light into two separate beams of light, one of said two light beams caused to be incident at a point on one of said stereoscopic images and the other of said two light beams caused to be incident on a corresponding point on the other of said stereoscopic images; and

means for deflecting said two light beams to scan corresponding areas on both stereoscopic images.

6. The improvement of claim 5 wherein said light source is a laser.

7. The improvement of claim 2 wherein said means for scanning scans a predetermined area about predetermined points on each of said plurality of parallel lines in a predetermined order and wherein said means for forming blocks of digital data forms blocks of data indicative of each predetermined area generated by scanning about each predetermined point.

8. The improvement of claim 2 wherein said means for scanning, line scans along a line transverse to the direction of the translation said line scan crossing each of the plurality of parallel lines and wherein said means for forming blocks of digital data forms blocks of digital data indicative of the data generated along each line scan respectively.

9. The improvement of claim 8 wherein said means for correlating further includes:

buffer storage means for temporarily storing said received blocks of digital data;

means for sequentially extracting from said buffer storage corresponding segments of data, one corresponding data segment from each stored data block indicative of the digital data a predetermined distance both sides of one of said plurality of parallel lines; and

parallel processor means for correlating said data segments to generate correlation data about each of said plurality of parallel lines.

10. The improvement of claim 9 wherein said buffer storage means temporarily stores one block of digital data generated by the line scan on one stereoscopic image and three blocks of data generated by three successive line scans on the other stereoscopic image, wherein one of said three blocks of data is said other block of data indicative of corresponding imagery;

said means for sequentially extracting further extracts from the other two blocks of data, data segments indicative of the digital data a predetermined distance both sides of the same one of said plurality of parallel lines; and

said parallel processor means correlates said one data segment with each of said three segments to generate said Correlation data; and

wherein said means for generating parallax data generates parallax data indicative of both the shifted relationship between the data correlated and the data block from which the segment having maximum correlation was extracted, thereby providing parallax data both transverse and parallel to each of said plurality of parallel lines.

11. The improvement of claim 8 wherein said means for scanning, line scans along epipolar lines on both stereoscopic images.

12. A system for generating parallax data from a pair of stereoscopic images about a plurality of parallel lines comprising:

means for generating, from said stereoscopic images, blocks of digital data indicative of corresponding imagery on both of said stereoscopic images about a plurality of parallel lines disposed parallel to the direction of a mechanical translation;

means for mechanically translating both of said stereoscopic images relative to said means for generating blocks of digital data along corresponding lines on each stereoscopic image parallel to said plurality of parallel lines;

means for temporarily storing said blocks of digital data in a predetermined sequence;

means receiving at least two blocks of digital data from said storage means, one block of data indicative of the imagery on one stereoscopic image and the other block of data indicative of the corresponding imagery on the other stereoscopic image for correlating the data in said at least two blocks of digital data in a plurality of shifted relationships to generate correlation data indicative of the correlation at each shifted relationship;

means receiving said correlation data for generating parallax data indicative of the shifted relationship between the data in said at least two blocks of digital data when said correlation data is indicative of a maximum correlation; and

means receiving said parallax data for generating a data transfer signal transferring the next two data blocks to be correlated from the storage means to the correlation means and a parallax address modification signal to shift the data in one of the two blocks of digital data transferred to the correlation means to the shifted relationship having maximum correlation during the correlation of the two blocks of data just previously correlated.

13. The system of claim 12 wherein said means for generating blocks of digital data comprises:

means having a repetitious scan pattern for individually scanning corresponding areas on both stereoscopic images about said plurality of parallel lines with a point of light to generate light signals modulated by the imagery in each of the scanned corresponding areas;

detector means for converting said modulated light signals into analog electrical signals;

means associated with said means for scanning for generating digital address signals at predetermined intervals indicative of the position of said point of light during the scanning of said corresponding areas;

means responsive to said digital address signals for sampling said analog electrical signals to generate digital data indicative of the imagery on both stereoscopic images at said predetermined intervals; and

means temporarily storing the digital data generated during each scan of both stereoscopic images for forming individual blocks of image data indicative of the imagery on the individual stereoscopic images within each repetitive scan pattern.

14. The system of claim 13 wherein said stereoscopic images have known geometrical distortions, said means for sampling further includes means responsive to distortion signals indicative of said known geometrical distortions for controlling the predetermined intervals at which said samples are taken to correct for the known geometrical distortions in the stereoscopic images.

15. The system of claim 14 wherein said means for scanning comprises:

two cathode ray tubes, each having an electron beam generating a point of light on the face of each tubE;

means for individually focusing both of said points of light on the stereoscopic images, one point of light being focused on one stereoscopic image and the other point of light being on a corresponding point on the other stereoscopic image; and

means for deflecting said electron beams to cause said points of light to scan corresponding areas respectively on each of said stereoscopic images.

16. The system of claim 14 wherein said means for scanning comprises:

a light source for generating a narrow beam of light;

means for dividing said narrow beam of light into two separate beams of light, one of said two light beams caused to be incident at a point on one of said stereoscopic images and the other of said two light beams caused to be incident on a corresponding point on the other of said stereoscopic images; and

means for deflecting said two light beams to scan corresponding areas on both stereoscopic images.

17. The system of claim 16 wherein said light source is a laser.

18. The system of claim 13 wherein said means for scanning scans a predetermined area about predetermined points on each of said plurality of parallel lines in a predetermined order and wherein said means for forming blocks of digital data forms blocks of data indicative of each predetermined area generated by scanning about each predetermined point.

19. The system of claim 13 wherein said means for scanning line scans along a line transverse to the direction of the translation said line scan crossing each of the plurality of parallel lines and wherein said means for forming blocks of digital data forms blocks of digital data indicative of the data generated along each line scan respectively.

20. The system of claim 19 wherein said means for correlating further includes:

buffer storage means for temporarily storing said received blocks of digital data;

means for sequentially extracting from said buffer storage corresponding segments of data, one corresponding data segment from each stored data block indicative of the digital data a predetermined distance either side of one of said plurality of parallel lines; and

parallel processor means for correlating said data segments to generate correlation data about each of said plurality of parallel lines.

21. The system of claim 20 wherein said buffer storage means temporarily stores one block of digital data generated by the line scan on one stereoscopic image and three blocks of data generated by three successive line scans on the other stereoscopic image, wherein one of said three blocks of data is said other block of data indicative of corresponding imagery;

said means for sequentially extracting further extracts from the other two blocks of data, data segments indicative of the digital data a predetermined distance both sides of the same one of said plurality of parallel lines; and

said parallel processor means correlates said one data segment with each of said three segments to genertate said correlation data; and

wherein said means for generating parallax data generates parallax data indicative of both the shifted relationship between the data correlated and data block from which the segment having maximum correlation was extracted, thereby providing parallax data both transverse and parallel to each of said plurality of parallel lines.

22. The system of claim 19 wherein said means for scanning, line scans along epipolar lines on both stereoscopic images.

23. A method for generating, from a pair of stereoscopic images, parallax data along each line of a plurality of parallel lines during a single mechanical translation of the stereoscopic images comprising:

scanning corresponding areas on the stereoscopic images about a plurality of parallel lines disposed parallel to the direction of the mechanical translation to generate blocks of digital image data indicative of the image detail in the areas scanned on both stereoscopic images;

temporarily storing in a storage meaNs said blocks of digital image data in a predetermined sequence;

correlating in a correlating means the digital image data from at least two blocks of image data, transferred from said storage means, in a plurality of shifted relationships to generate correlation data indicative of the correlation at each shifted relationship, one block of image data extracted from said storage means indicative of the image detail in the scanned area on one stereoscopic image and the other of said at least two blocks of data indicative of the corresponding image detail on the other stereoscopic image;

generating parallax data from said correlation data indicative of the shifted relationship between said at least two blocks of digital data when said correlation data is indicative of maximum correlation; and

generating, from said parallax data, data transfer signals to transfer the next two blocks of digital data to be correlated from the storage means to said correlation means and parallax address modification signals to shift the data in one of said at least two blocks of digital data transferred, to the shifted relationship having maximum correlation during the correlation of the two blocks of data just previously correlated.

24. The method of claim 23 wherein said step of scanning comprises:

scanning with a repetitive scan pattern corresponding areas on both sterosscopic images about said plurality of parallel lines with a point of light to generate light signals modulated by the image detail in each of the scanned corresponding areas;

detecting said modulated light signals to generate analog electrical signals;

generating digital address signals at perdetermined intervals indicative of the position of said points of light during the scanning of said corresponding areas;

sampling said analog electrical signals with said digital address signals to generate digital data indicative of the image detail on both stereoscopic images at said predetermined intervals; and

accumulating said digital data generated within each repetitive scan pattern to form individual blocks of digital data, each block of digital data being associated with one steroscopic image and one repetitive scan pattern.

25. The method of claim 24 wherein said steroscopic images have known geometrical distortions, said method further includes the steps of:

generating distortion signals indicative of the known geometrical distortions; and

modifying said geometrical address signals with said distortion signals to change the predetermined intervals at which said samples are taken to compensate for the known geometrical distortions.

26. the method of claim 25 wherein said step of scanning comprises:

generating, on the face of two cathode ray tubes having electron beams the two points of light, one point of light being on one of said two cathode ray tubes and the other point of light being on the other of said two cathode ray tubes;

individually focusing both of said points of light on the stereoscopic images, one point of light being focused on one sterescopic image and the other point of light on the corresponding point on the other stereoscopic image; and

deflecting said electron beams to cause said points of light to scan corresponding areas rescpectively on each of said stereoscopic images.

27. The method of claim 25 wherein said step of scanning comprises:

generating a narrow beam of light;

dividing said narrow beam of light into two separate beams of light, one of said two light beams caused to be incident at a point on one of said stereoscopic images and the other of said two light beams caused to be incident in a corresponding point on the other of said stereoscopic images; and

synchronously deflecting said two light beams by optical means to scan corresponding areas on both stereoscopic images.

28. The method of claim 27 wherein said step of generating a narrow beam of light includes generating a narrow beam of light by means of a laser.

29. The method of claim 24 wherein said step of scanning includes:

scanning predetermined areas about predetermined points on each of said plurality of parallel lines in a predetermined order and wherein said step of accumulating said digital data accumulates the data indicative of each predetermined area scanned about each predetermined point.

30. The method of cliam 24 wherein said step of acanning includes line scanning along a line traverse to the direction of the mechanical translation, said line scan crossing each of the plurality of parallel lines and wherein said accumulating step forms blocks of digital data indicative of the data generated along each line scanned respectively.

31. The method of claim 30 wherein said step of correlating further includes:

temporarily storing said blocks of digital data in a buffer storage;

sequentially extracting from said buffer storage corresponding segments of data, one corresponding data segment from each data block indicative of the digital data a predetermined distance both sides of one of said plurality of parallel lines; and

correlating said data segments to generate correlation about said one of said parallel lines.

32. The method of claim 31 wherein:

said step of storing in a buffer storage includes storing one block of digital data generated by a line scan on one of said stereoscopic images and storing three blocks of digital data generated by three successive line scans on the other stereoscopic image wherein one of said three blocks of digital data is the other block of digital data of said at least two blocks of digital data indicative of corresponding image detail;

said step of extracting further includes the step of extracting from said three of said three blocks of digital data, data segments indicative of the digital data on a predetermined distance on both sides of the same one of said plurality of parallel lines;

said step of correlating further includes the steps of correlating said one data segment with each of said three data segments in a predetermined sequence to generate correlation data; and

wherein said step of generating parallax data further includes the step of generating parallax data indicative of which one of said three blocks of digital data, the segment having maximum correlation was extracted, thereby generating parallax data both transverse and parallel to each of said plurality of parallel lines.

33. The method of claim 30 wherein said step of scanning, line scans along epipolar lines on both of the stereoscopic images.