Method for Determination of the Direction to an Object to be Surveyed

• US 20080116354A1
• Filed: 09/10/2004
• Published: 05/22/2008
• Est. Priority Date: 09/12/2003
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Kirschner, Holger, Graf, Roland
• Granted Patent: US 7,842,911 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: G01C 1/04 combined with cameras
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01S 3/784 using a mosaic of detectors

Abstract

According to the invention, an image (4) with a form (6) of the object is recorded, for the purpose of measuring the direction to said object, the further surveying of which will follow. In order to achieve an optimum stability for the above for rapid changes to the object position, the capabilities of modern image sensors are used to analyse or download only a part of the available pixels. A selection of analysed image information, as above, uses information about the required measurement accuracy and the time performance of the image sensor. According to the invention, such a limitation to the downloaded information can be achieved by the selection of a partial region (7b) of the image (4) by the combination of a sub-sampling with a sub-windowing. A selection of image points for downloading within the partial region (7a) of the image (4) can thus be achieved by means of targeted omission.

Claims

1. (canceled)

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3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

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11. (canceled)

12. A method for determination of the direction to an object to be surveyed, using a geodetic measuring instrument comprising an image sensor, the field of view of which sensor detects at least part of the object to be surveyed, the method comprising the following acts:

recording an image with image information using the image sensor the image having a pattern which can be coordinated with the object, wherein the position of the pattern within the image permits a determination of the direction to the object;

determining the position of the pattern within the image; and

deriving direction information coordinated with the object from the position of the pattern, the direction from a detection point coordinated with the image sensor to the object being determined, wherein only a portion of the image information is selected and used for the direction determination, and wherein the portion of the image information is selected with regard to a specified accuracy of measurement.

13. A method according to claim 12, further comprising periodically omitting pixels, the periodicity being chosen so that the local resolvability of the position of the pattern permits the determination of the direction to the object with the specified accuracy of measurement.

14. A method according to claim 12, wherein the act of recording the image further comprises subwindowing as a selection of a partial region of the image sensor and subsampling as a specific omission of pixels within the partial region.

15. A method according to claim 12, wherein the act of deriving the direction information further includes verifying that the object is positioned at least partly within the field of view of the sensor.

16. A method according to claim 14, wherein specification of subsampling parameters is effected before specification of the subwindowing parameters.

17. A method according to claim 14, wherein the selection of the partial region is made during the subwindowing on the basis of at least one of the following variables:

object size;

object distance;

desired accuracy of measurement;

dimensions of the pattern; and

expected or measured maximum angular acceleration.

18. A method according to claim 14, further comprising omitting a selection of pixels during the subsampling on the basis of at least one of the following variables:

object size;

object distance;

desired accuracy of measurement;

dimensions of the pattern; and

expected or measured maximum angular acceleration.

19. A method according to claim 12, further comprising omitting columns and/or rows of the image sensor during the subsampling.

20. A method according to claim 19, wherein the omitted columns and/or rows are in the form of a rectangular partial region of the image sensor.

21. A method according to claim 14, wherein the act of subsampling includes omitting pixels in a regular or stochastic sequence.

22. A computer program product having a program code, which is stored on a machine-readable medium, configured to carry out the method according to claim 12.

23. An analogue or digital computer data signal, embodied by an electromagnetic wave, having a program code segment configured to carry out the method of claim 12.