Optical instrument and method for obtaining distance and image information

• US 8,368,875 B2
• Filed: 07/22/2009
• Issued: 02/05/2013
• Est. Priority Date: 01/26/2007
• Status: Active Grant

• Current Assignee: Trimble Jena GmbH (Trimble Inc.)
• Original Assignee: Trimble Jena GmbH (Trimble Inc.)
• Inventors: Kludas, Torsten, Vogel, Michael, Grasser, Christian, Svanholm, Set
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US12/507,753
• Publication Number:
  US 20100030515A1
• Time in Patent Office: 1,294 Days
• Field of Search: 356/4.01, 356/4.03, 356/4.04, 382/103, 382/106
• US Class Current: 356/5.01
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105

Abstract

An optical instrument and a method for obtaining distance and image information of an object is disclosed to improve the speed and accuracy of data acquisition. The instrument comprises a camera, positioning unit, distance measuring unit, lens arrangement and control unit. The camera acquires images of an object and the control unit defines an area to be scanned as well as an object feature of the object, wherein measurement pixels corresponding to positions on the object may be defined in the area with an increased density of measurement pixels at the object feature. Subsequently, the distances to the object at the selected positions of interest are measured.

Claims

1. An optical instrument for obtaining distance and image information of an object, comprising:

a lens arrangement for sighting the object;

a camera aligned with the optical axis of the lens arrangement for acquiring an image of at least part of the object;

a distance measuring unit for measuring a distance to the object along a measurement axis of the distance measuring unit parallel to the optical axis of the lens arrangement;

a positioning unit for adjusting the optical axis of the lens arrangement relative to at least one reference axis; and

a control unit comprising;

a first control element adapted to define in the image an area to be scanned, to obtain an object feature of the object in the defined area and to define in the area a plurality of measurement pixels corresponding to a plurality of positions on the object with an increased density of measurement pixels at the object feature compared to other parts of the object; and

a second control element adapted to instruct the positioning unit to adjust the optical axis of the lens arrangement sequentially onto the plurality of positions on the object and to instruct the distance measuring unit to measure the distances to the object at the plurality of positions,

wherein the first control element is adapted to define the area to be scanned by an operator for selecting the area in the image or by processing the image using a detection algorithm for detecting the at least part of the object, and

wherein the first control element is adapted to define in the area to be scanned a region with a high measurement pixel density being a region with large variations in structure, a region with a low measurement pixel density being a region with small variations in structure, and a region without measurement pixels.

2. The optical instrument of claim 1 wherein the first control element is adapted to obtain the object feature by an operator for selecting the object feature in the area or by processing the area in the image using a detection algorithm for detecting the object feature of the object in the area.

3. The optical instrument of claim 1 wherein the first control element is adapted to define the area to be scanned by an operator for selecting the area in the image or by processing the image using a detection algorithm for detecting the at least part of the object.

4. The optical instrument of claim 1 wherein the first control element is adapted to define in the area to be scanned at least one of a region with a high measurement pixel density, a region with a low measurement pixel density and a region without measurement pixels.

5. The optical instrument of claim 4 wherein the first control element is adapted to define the regions by an operator for selecting the regions in the area or by processing the area using a detection algorithm for detecting the regions in the area.

6. The optical instrument of claim 1 wherein the second control element is adapted to scan the measurement pixels in the area in a sequence so as to minimize an adjustment of the optical axis of the lens arrangement.

7. The optical instrument of claim 1 wherein the first control element is adapted to define in the area the plurality of measurement pixels by introducing a two-dimensional representation of a profile into the area and by selecting a plurality of pixels at an outline of the two-dimensional representation of the profile in the area as the measurement pixels.

8. The optical instrument of claim 1 wherein the image comprises at least a first and a second sub image and the at least two sub images comprise the plurality of measurement pixels.

9. The optical instrument of claim 8 wherein the first control element is further adapted to define other positions to be measured between the measurement pixels of the first sub image and the second sub image.

10. The optical instrument of claim 9 wherein the first control element is adapted to define the other positions to be measured by processing at least one of the first sub image and the second sub image by defining the other positions along a line connecting at least two measurement pixels or by using an extrapolation algorithm for extrapolating an edge or other object feature of the object in at least one of the first sub image and second sub image detected by a detection algorithm.

11. The optical instrument of claim 1 wherein the positioning unit is further adapted to measure horizontal and vertical angles to the plurality of the positions on the object with respect to a reference axis system.

12. The optical instrument of claim 1 further comprising a display unit for displaying the acquired image.

13. The optical instrument of claim 12 wherein the display unit is adapted to display the acquired image and the measured positions in superposition.

14. The optical instrument of claim 12 wherein the display unit is a touch display unit for at least one of defining in the image the area to be scanned by an operator and obtaining the object feature by an operator.

15. The optical instrument of claim 1 further comprising a conversion unit for converting the plurality of measurement pixels into coordinates of the positions to be measured.

16. The optical instrument of claim 15 wherein the conversion is performed using a conversion algorithm.

17. The optical instrument of claim 15 wherein the conversion is performed using a conversion table correlating each measurement pixel with coordinates of the positions to be measured.

18. The optical instrument of claim 1 wherein at least two of the plurality of measurement pixels constitute core point pixels and the first control element is adapted to convert the core point pixels into an approximation of coordinates of core positions to be measured assuming a default distance between the core positions and the optical instrument, and

the second control element is adapted to instruct the positioning unit to adjust the optical axis of the lens arrangement onto the core positions to be measured and to instruct the distance measuring unit to measure the distances to the core positions,

wherein the first control element is further adapted to recalculate the coordinates of the core positions based on the measured distances.

19. The optical instrument of claim 1 further comprising at least one of a transceiver for receiving control data and a detachable remote control unit with an operation control unit, a display unit and a transceiver to remotely control the optical instrument.

20. A method for obtaining distance and image information of an object, the method comprising:

sighting the object with a lens arrangement;

acquiring an image of at least part of the object with a camera aligned with the optical axis of the lens arrangement;

defining in the image an area to be scanned;

obtaining an object feature of the object in the defined area;

defining in the area a plurality of measurement pixels corresponding to a plurality of positions on the object with an increased density of measurement pixels at the object feature compared to other parts of the object;

adjusting the optical axis of the lens arrangement relative to at least one reference axis sequentially onto the plurality of positions on the object; and

measuring the distances to the object at the plurality of positions,

wherein defining of the area to be scanned comprises selecting the area in the image by an operator or by processing the image using a detection algorithm for detecting the at least part of the object, and

wherein the method further comprises defining in the area to be scanned a region with a high measurement pixel density being a region with large variations in structure, a region with a low measurement pixel density being a region with small variations in structure and a region without measurement pixels.

21. The method of claim 20 wherein the object feature is obtained by an operator selecting the object feature in the area or by processing the area in the image using a detection algorithm for detecting the object feature of the object in the area.

22. The method of claim 20 wherein the area to be scanned is defined by an operator selecting the area in the image or by processing the image using a detection algorithm for detecting the at least part of the object.

23. The method of claim 20 further comprising defining in the area to be scanned at least one of a region with a high measurement pixel density, a region with a low measurement pixel density and a region without measurement pixels.

24. The method of claim 23 wherein the region is defined by an operator selecting the regions in the area or by processing the area using a detection algorithm for detecting the regions in the area.

25. The method of claim 20 further comprising scanning the measurement pixels in the area in a sequence so as to minimize an adjustment of the optical axis of the lens arrangement.

26. The method of claim 20 wherein the plurality of measurement pixels in the area is defined by introducing a two-dimensional representation of a profile into the area and by selecting a plurality of pixels at an outline of the two-dimensional representation of the profile in the area as the measurement pixels.

27. The method of claim 20 wherein the image comprises at least a first and a second sub image and the at least two sub images comprise the plurality of measurement pixels.

28. The method of claim 27 further comprising defining other positions to be measured between the measurement pixels of the first sub image and the second sub image.

29. The method of claim 28 wherein the other positions to be measured are defined by processing at least one of the first sub image and the second sub image by defining the other positions along a line connecting at least two measurement pixels or by using an extrapolation algorithm for extrapolating an edge or other object feature of the object in at least one of the first sub image and second sub image detected by a detection algorithm.

30. The method of claim 20 further comprising measuring horizontal and vertical angles to the plurality of the positions on the object with respect to a reference axis system.

31. The method of claim 20 further comprising displaying the acquired image.

32. The method of claim 31 wherein the acquired image and the measured positions are displayed in superposition.

33. The method of claim 31 further comprising defining by an operator on a touch display unit at least one of the area to be scanned and the object feature.

34. The method of claim 20 further comprising converting the plurality of measurement pixels into coordinates of the positions to be measured.

35. The method of claim 34 wherein the conversion is performed using a conversion algorithm.

36. The method of claim 34 wherein the conversion is performed using a conversion table correlating each measurement pixel with coordinates of the positions to be measured.

37. The method of claim 20 further comprising receiving control data to remotely control the control unit.

38. The method of claim 20 wherein at least two of the plurality of measurement pixels constitute core point pixels, the method further comprising:

converting the core point pixels into an approximation of coordinates of core positions to be measured assuming a default distance to the core positions;

adjusting the optical axis of the lens arrangement onto the core positions to be measured;

measuring the distances to the core positions; and

recalculating the coordinates of the core positions based on the measured distances.

39. A program including instructions adapted to cause data processing means to carry out the method of claim 20.

40. A computer readable medium, in which a program is embodied, where the program is configured to make a computer execute the method of claim 20.

41. A computer program product comprising the computer readable medium according to claim 40.