Method and apparatus for measuring coordinates

• US 4,803,645 A
• Filed: 09/18/1986
• Issued: 02/07/1989
• Est. Priority Date: 09/19/1985
• Status: Expired due to Term

• Current Assignee: Tokyo Kogaku Kikai Kabushiki Kaisha 75-1 Hasunuma-Cho Itabashi-Ku Tokyo Japan
• Original Assignee: Tokyo Kogaku Kikai Kabushiki Kaisha
• Inventors: Ohtomo, Fumio, Otani, Hitoshi
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Teska, Kevin J.
• Application Number:
  US06/909,254
• Time in Patent Office: 873 Days
• Field of Search: 364/168, 364/525, 364/560-562, 33/504, 356/1, 356/2, 356/4, 356/12, 356/376, 356/390, 250/560, 358/3, 358/92, 358/146
• US Class Current: 702/167
• CPC Class Codes: G01C 11/06 by comparison of two or more pictures of the same area
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G06T 7/593 from stereo images

Abstract

A coordinates measuring method in which the image information of the same point are derived as first, second and third information when viewed from at least three different directions, a first corresponding point is determined by deriving the correlation between the first and second information, and a second corresponding point is determined by deriving the correlation between the second and third information, and mismatching is decided when the first and second coordinates are not substantially coincident with each other.

Claims

1. Apparatus for measuring the coordinates of a point on a three-dimensional object, said apparatus comprising:

detection means for viewing said object from at least three different directions and deriving three uniquely different kids of image information representative of a point on said object respectively designated first, second and third image information;

correlation means coupled to said detection means including means for setting said second image information as a measured reference point, means for deriving a correlation between said first image information and said second image information for producing information defining a first corresponding point correspondent to said measured reference point, and means for deriving a correlation between said second image information and said third image information for producing information defining a second correspondent point corresponding to said measured reference point;

computation means for computing a first signal representing first coordinates of said point from information defining said measured reference point and said first corresponding point, and for computing a second signal representing second coordinates of said point from information defining said measured reference point and said second corresponding point; and

decision circuit means connected to receive said first and second signals respectively representing said first and second coordinates for determining whether or not said first and second coordinates are substantially in coincidence with each other and for indicating a mismatch when they are not substantially coincident.

2. Apparatus for measuring coordinates according to claim 1, wherein said detection unit comprises three optical systems for forming respective images in overlapped relation of the measured three-dimensional object as viewed from three different directions, and three image sensors arranged at respective focus points of the images formed by said three optical systems.

3. Apparatus for measuring coordinates according to claim 2, wherein said second image information is derived by viewing said object from a direction between two directions from which said first and third image information are respectively derived, and wherein said computation means also computes a third signal representing third coordinates of said measured point from information defining said first and said second corresponding points.

4. Apparatus for measuring coordinates according to claim 1, for detecting said first, second and third image information from image information contained in at least three photographs taken with parallax therebetween.

5. Apparatus for measuring coordinates according to claim 4, wherein said detection unit has an image sensor for each of said photographs arranged in one to one correspondence therewith.

6. A method for measuring the coordinates of a point of a three-dimensional object, said method comprising the steps of:

viewing said object from three different directions for deriving three uniquely different kinds of image information of said point, designated first, second and third image information;

designating said second image information as a measured reference point;

deriving a correlation between said first image information and said second information and producing information defining a first corresponding point correspondent to said measured reference point;

deriving a correlation between said second image information and said third image information and producing information defining a second correspondent point corresponding to said measured reference point;

determining first coordinates from information defining said measured reference point and said first corresponding point;

determining second coordinates from information defining said reference point and said second corresponding point;

determining whether or not said first and second coordinates are substantially coincident with each other and indicating a mismatch when they are not; and

upon determining substantial coincidence of said first and second coordinates, determining measured coordinates of said point on the three-dimensional object from information defining any two points among said first corresponding point, said second corresponding point, and said measured reference point.

7. A method for measuring coordinates according to claim 6, wherein said first-mentioned step is carried out by deriving said second information by viewing the object from a direction between the two directions from which said object is viewed to derive said first and third information, respectively, and wherein said last-mentioned step is carried out by determining the measured coordinates based on said first and said second corresponding points.