MAPPING RECTIFIER FOR GENERATING POLARSTEREOGRAPHIC MAPS FROM SATELLITE SCAN SIGNALS

• US 3,716,669 A
• Filed: 05/14/1971
• Issued: 02/13/1973
• Est. Priority Date: 05/14/1971
• Status: Expired due to Term

• Current Assignee: Kantaro Watanabe
• Original Assignee: Kantaro Watanabe
• Inventors: Watanabe, Kantaro (N/A)
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US05/143,454
• Time in Patent Office: 641 Days
• Field of Search: 178/6.5,6.8,6.7R 343/5,5PC,17 355/52
• US Class Current: 348/147
• CPC Class Codes: G01C 11/04 Interpretation of pictures
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G09B 29/007 using computer methods

Abstract

Disclosed is a system including electrical, mechanical and optical components and serving to generate polarstereographic maps of the Earth surface from scan signals sent by meteorological satellites such as Nimbus. The satellite scan signals are received by suitable radio equipment and are used to generate scan line images on a cathode ray tube having a concave face matching the Earth'"'"''"'"'s curvature to compensate for the face that the satellite scans a spherical surface. The cathode ray tube is positioned along a circular track such that a scan line image on the CRT concave face is congruent with a sphere concentric with the track. Two diametrically opposite points of the sphere are designated South and North pole respectively, and a photocamera is positioned near the track such that the front nodal point of its lens is at either the South or the North pole of the sphere. The purpose of the circular track system is to compensate for the orbital motion of the satellite around the Earth and to project on planar film in the camera a polarstereographic projection of the scanned Earth surface. To that end, the cathode ray tube and the camera are moved with respect to each other along the circular track in synchronism with the orbital motion of the satellite around the Earth while the camera remains with the front nodal point of its lens at the South (or North) pole point of the track. The camera has a zoom control which keeps the front nodal point of the camera lens at the South (or North) Pole as the cathode ray tube and the camera move with respect to each other. A compensation is made for the east-west rotation of the Earth by means of rotating the camera around the North-South axis of the track. A further compensation is made for inclination of the satellite orbit from the Earth axis by means of adjusting the orientation of the camera with respect to the track plane. Lee than a 360* track may be used if a map of only a portion of the scanned Earth surface is desired.

Claims

1. Apparatus for generating polarstereographic projection maps of a spherical body such as the Earth from satellite scan signals comprising:

a. a curved screen coinciding with a portion of an imaginary sphere proportional in size to the scanned spherical body;

b. means for generating on the curved screen representations of the satellite scan signals resulting in a curved screen image representative of an area of the spherical body from which satellite scan signals are derived;

c. a map screen; and

d. means for projecting the curved screen image onto the map screen to generate on the map screen polarstereographic map projections of portions of the curved screen image.

2. Apparatus as in claim 1 wherein the curved screen is concave and is the face of a cathode ray tube coinciding with a portion of the imaginary sphere;

and wherein the means for generating the curved screen image includes means for converting satellite scan signals transmitted from the satellite into beam control signals for the cathode ray tube.

3. Apparatus as in claim 1 including means for positioning the map screen substantially perpendicularly to an axis of the imaginary sphere corresponding to the pole-to-pole axis of the spherical body.

4. Apparatus as in claim 3 wherein the means for projecting the curved screen image onto the map screen includes lens means having a front nodal point coinciding with a point at which the imaginary sphere axis intersects the imaginary sphere and projecting onto the map screen polarstereographic map projections of portions of the curved screen image.

5. Apparatus as in claim 4 including means for maintaining a tilting angle between the lens means and the curved screen resulting in coincidence between the lens means plane passing through a rear nodal point of the lens means and the line of the intersection of the plane of the map screen and a plane tangent to the imaginary sphere at the center of the curved screen image on the curved screen.

6. Apparatus as in claim 4 including means for compensating for the orbital motion of the satellite around the spherical body comprising means for moving the map screen and the curved screen with respect to each other in synchronism with the satellite motion around the spherical body while retaining the position of the map screen with respect to the imaginary sphere axis.

7. Apparatus as in claim 6 including zoom control means synchronized with the relative motion between the curved screen and the map screen to retain the relative position of the lens means front nodal point with respect to the imaginary sphere during said relative motion, and to retain the relative position of the lens means rear nodal point and the map screen.

8. Apparatus as in claim 6 wherein the compensating means includes at least a portion of a Circular track coinciding with a cross-section of the imaginary sphere, and means for moving the map screen along the circular track in synchronism with the satellite rotation around the spherical body while retaining the position of the map screen with respect to the imaginary sphere axis.

9. Apparatus as in claim 4 including means for compensating for rotation of the spherical body with respect to the orbital plane of the satellite.

10. Apparatus as in claim 9 wherein the compensating means includes means for causing relative motion between the map screen and the curved screen, said relative motion having the same effect as rotating the map screen around the axis of the imaginary sphere in synchronism with the rotation of the spherical body with respect to the satellite orbital plane, while retaining the angle between the map screen and the imaginary sphere axis.

11. Apparatus as in claim 10 wherein the map screen comprises a photographic film plate recording permanently the curved screen image.

12. Apparatus as in claim 4 including means for compensating for inclination of the satellite orbital plane with respect to the axis of rotation of the spherical body.

13. Apparatus as in claim 12 wherein the means for compensating for inclination comprises means for changing the angle between the map screen and the curved screen by an amount proportional to the inclination of the satellite orbital plane from the axis of the rotation of the spherical body.

14. Apparatus as in claim 13 wherein the angle which is being changed to compensate for inclination between the satellite orbital plane and the axis of rotation of the spherical body is in a plane which includes, when the map screen and the curved screen are diametrically opposite, the axis of the imaginary sphere corresponding to the axis of rotation of the spherical body and a screen image on the curved screen, said screen image representing a satellite scan.

15. Apparatus as in claim 3 including means for compensating the map screen projection for motion of the satellite around the spherical body.

16. Apparatus as in claim 15 including means for compensating the map screen projection for rotational motion of the spherical body with respect to the orbital plane of the satellite.

17. Apparatus as in claim 16 including means for compensating the map screen projection for inclination between the orbital plane of the satellite and the axis of rotation of the spherical body.