METHOD AND MEASUREMENT SYSTEM FOR CONTACTLESS COORDINATE MEASUREMENT ON AN OBJECT SURFACE

• US 20110317880A1
• Filed: 09/06/2011
• Published: 12/29/2011
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems Holdings AG (Hexagon AB)
• Inventors: PETTERSSON, Bo, ZEBHAUSER, Benedikt, SIERCKS, Knut
• Granted Patent: US 8,244,030 B2
• Time in Patent Office: Days
• US Class Current: 382/106
• CPC Class Codes: G01B 11/005 coordinate measuring machines
• CPC Class Codes: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging

Abstract

The invention relates to a method and a surveying system for noncontact coordinate measurement on the object surface of an object to be surveyed in an object coordinate system. With a 3D image recording unit, a first three-dimensional image of a first area section of the object surface is electronically recorded in a first position and first orientation, the first three-dimensional image being composed of a multiplicity of first pixels, with which in each case a piece of depth information is coordinated. The first position and first orientation of the 3D image recording unit in the object coordinate system are determined by a measuring apparatus coupled to the object coordinate system. First 3D object coordinates in the object coordinate system are coordinated with the first pixels from the knowledge of the first 3D image coordinates and of the first position and first orientation of the 3D image recording unit.

Claims

1. A method for noncontact coordinate measurement to an object surface of an object to be surveyed in an object coordinate system, comprising:

a first three-dimensional image of a first area section of the object surface is electronically recorded by means of a 3D image recording unit in a first position and first orientation, the first three-dimensional image being composed of a multiplicity of first pixels, with which in each case a piece of depth information is coordinated;

first 3D image coordinates in an image coordinate system of the 3D image recording unit are coordinated with the first pixels;

the first position and first orientation of the 3D image recording unit in the object coordinate system are determined by a measuring apparatus coupled to the object coordinate system;

first 3D object coordinates in the object coordinate system are coordinated with the first pixels from the knowledge of the first 3D image coordinates and of the first position and first orientation of the 3D image recording unit;

the measuring apparatus is in the form of an adjustable mechanical articulated 3D coordinate-measuring arm, comprising;

a first end coupled in the object coordinate system;

an opposite moveable measuring second end;

a plurality of arm sections arranged between the first end and the second end, and pivotably and/or rotatably connected to one another by means of pivot joints in such a way that the moveable measuring second end is freely moveable within a first spatial section; and

angle sensors which are coordinated with the pivot joints for determining the angle position of the respective pivot joint;

the moveable measuring second end is coupled in a defined manner to the 3D image recording unit;

the first position and first orientation of the 3D image recording unit in the object coordinate system are determined from the knowledge of the angle positions of the pivot joints and of the lengths of the arm sections; and

the first end coupled in the object coordinate system;

is positioned in a first position for recording the first three-dimensional image of the first area section by the 3D image recording unit whose first position and first orientation is determined within the first spatial section; and

is positioned in a second position for recording at least one further three-dimensional image of at least one further area section by the 3D image recording unit in at least one further position and further orientation within a second spatial section.

2. The method as claimed in claim 1, wherein:

the 3D image recording unit is brought from the first position and first orientation into at least one further position and further orientation;

at least one further three-dimensional image of at least one further area section of the object surface is electronically recorded with the 3D image recording unit in the further position and further orientation;

the further position and further orientation of the 3D image recording unit are determined in the object coordinate system by means of the measuring apparatus; and

further 3D object coordinates in the object coordinate system are coordinated with the further pixels of the further three-dimensional image from the knowledge of the further 3D image coordinates of the further three-dimensional image and the further position and further orientation of the 3D image recording unit.

3. The method as claimed in claim 2, wherein:

the first area section and the at least one further area section of the object surface partly overlap; and

the first three-dimensional image having the first 3D object coordinates and the at least one further three-dimensional image having the further 3D object coordinates are combined to give a cohesive three-dimensional image.

4. The method as claimed in claim 1, wherein the measuring apparatus is substantially decoupled from retaining forces which act during holding of the 3D image recording unit.

5. The method as claimed in claim 4, wherein the 3D image recording unit is held by a retaining device, which substantially absorbs the retaining forces, during image recording.

6. The method as claimed claim 1, wherein the moveable measuring second end which is coupled to the 3D image recording unit is moveable in six degrees of freedom.

7. The method as claimed in claim 1, wherein:

the first position of the first end is determined by a first ground anchor, which is referenced in the object coordinate system and in which the coupled first end is fixed,

the second position of the first end is determined by a second ground anchor, which is referenced in the object coordinate system and in which the coupled first end is fixed, and

the articulated 3D coordinate-measuring arm is coupled to the object coordinate system;

by the first ground anchor for determining the first position and first orientation of the 3D image recording unit; and

by the second ground anchor for determining the at least one further position and further orientation of the 3D image recording unit.

8. The method as claimed in claim 1, wherein:

the first position and the second position of the first end are optically determined by an optical reference laser measuring system which is referenced in the object coordinate system; and

the articulated 3D coordinate-measuring arm is coupled to the object coordinate system by the optical reference laser measuring system;

for determining the first position and first orientation; and

for determining the at least one further position and further orientation.

9. The method as claimed in claim 1, wherein the 3D image recording unit comprises at least two electronic cameras, which record the first area section from at least two different recording angles, for producing the three-dimensional image.

10. A surveying system for noncontact coordinate measurement on the object surface of an object to be surveyed in an object coordinate system, comprising:

a 3D image recording unit;

which is formed for electronic recording of a first three-dimensional image of a first area section of the object surface, the first three-dimensional image being composed of a multiplicity of first pixels with which in each case a piece of depth information is coordinated; and

electronically outputs the first 3D image coordinates which are coordinated with the first pixels in an image coordinate system;

a measuring apparatus;

which can be coupled to the object coordinate system; and

which is formed for determining a first position and first orientation of the 3D image recording unit in the object coordinate system,

wherein the measuring apparatus is in the form of an adjustable mechanical articulated 3D coordinate-measuring arm, comprising;

a first end which can be coupled in the object coordinate system,

an opposite moveable measuring second end,

a plurality of arm sections arranged between the first end and the second end, and pivotably and/or rotatably connected to one another by means of pivot joints in such a way that the moveable measuring second end is freely moveable within a first spatial section, and

angle sensors which are coordinated with the pivot joints for determining the angle position of the respective pivot joint, the moveable measuring second end being coupled in a defined manner to the 3D image recording unit and the articulated 3D coordinate-measuring arm being formed in such a way that the first position and first orientation of the 3D image recording unit in the object coordinate system can be determined from the knowledge of the angle positions of the pivot joints and the lengths of the arm sections;

an optical reference laser measuring system which is referenced in the object coordinate system; and

a data processing unit;

to which the first 3D image coordinates are fed from the 3D image recording unit and the first position and first orientation of the 3D image recording unit are fed from the measuring apparatus;

which has a signal link to the data processing unit for coupling the first end to the object coordinate system;

which is formed in such a way that first 3D object coordinates in the object coordinate system are electronically coordinated with the first pixels from the knowledge of the first 3D image coordinates and of the first position and first orientation of the image recording unit; and

which outputs a signal which contains the first 3D object coordinates coordinated with the first pixels.

11. The surveying system as claimed in claim 10, wherein the measuring apparatus is substantially decoupled from retaining forces which act during holding of the 3D image recording unit.

12. The surveying system as claimed in claim 11, further comprising a retaining device which substantially absorbs retaining forces, acting during holding of the 3D image recording unit, during the image recording.

13. The surveying system as claimed in claim 10, wherein the moveable measuring second end which is coupled to the 3D image recording unit is moveable in six degrees of freedom.

14. The surveying system as claimed in claim 10, wherein the 3D image recording unit comprises at least two electronic cameras, which record the first area section from at least two different recording angles, for producing the three-dimensional image.