Apparatus and method for determining the coordinates of a three-dimensional object

• US 4,858,157 A
• Filed: 03/11/1986
• Issued: 08/15/1989
• Est. Priority Date: 03/13/1985
• Status: Expired due to Term

• Current Assignee: Tokyo Kogaku Kikai Kabushiki Kaisha
• Original Assignee: Tokyo Kogaku Kikai Kabushiki Kaisha
• Inventors: Ohtomo, Fumio, Murai, Shunji, Ohtani, Hitoshi
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Dixon, Joseph L.
• Application Number:
  US06/838,577
• Time in Patent Office: 1,253 Days
• Field of Search: 364/560, 364/561, 364/562, 364/563, 364/525, 382/1, 382/8, 382/30, 356/1, 356/2, 356/4, 356/376, 356/390, 358/88, 358/91, 358/92
• US Class Current: 382/154
• CPC Class Codes: G01C 11/06 by comparison of two or more pictures of the same area

Abstract

A coordinates measuring apparatus comprising a detecting unit constituted by an optical system for obtaining an image of an object and a detecting system having a plurality of arrayed detecting elements disposed in such a manner that respective detecting signals are superposed at the position of said image, a control unit for taking out data from each of said arrayed detecting elements, and a storage unit for storing the data of each array taken out from said control unit.

Claims

1. Apparatus for determining the coordinates of a measurement point on a three-dimensional object comprising, in combination:

first and second photoelectric conversion means disposed at a selected height from the object and spaced apart a predetermined distance in the direction of an x-axis and moveable together incrementally in the direction of a y-axis for respectively generating first and second data signals respectively representing first and second images of said object each divided into a plurality of measurement points and together constituting a stereoscopic image;

first and second memory means respectively connected to said first and second photoelectric conversion means for respectively storing said first and second data signals representing said first image and said second image, respectively;

measurement point setting means for storing data signals representing x and y coordinates of measurement points in said first image;

correlation processing means connected to said first and second memory means and to said measurement point setting means for processing output signals from said first and second memory means and data signals from said measurement point setting means representing a selected measurement point in said first image and producing a measurement point in the second image substantially corresponding to the selected measurement point in said first image;

mark generating means connected to said first and second memory means for adding to the data signal representing said first image a mark data signal concerning said selected measurement point and for adding to the data signal representing said second image a corresponding mark data signal concerning the measurement point supplied from said correlation processing means;

image display means including a display screen and video signal control circuit means for raster scanning said display screen at a predetermined vertical synchronization frequency;

signal processing means including means for applying the data signal representing said first image and containing said mark data signal to said image display means alternately with the data signal representing said second image and containing said corresponding mark data signal each at one-half the vertical synchronization frequency for producing on said display screen an image of said object including images of said mark data signal and said corresponding data signal, and means through which the display screen image of said object is viewed alternately with the left and right eye each at one-half said vertical synchronization frequency for presenting a three-dimensional image of said object and enabling visual examination to determine whether the image of the measurement point in said second image is correctly positioned in the viewed image; and

calculating means connected to said correlation processing means and to said measurement point setting means for calculating values of the x, y, and height (z) coordinates of said selected measurement point when the image of the measurement point in said second image is determined to be correctly positioned in the viewed image.

2. Apparatus for determining the coordinates of a measurement point on a three-dimensional object according to claim 1, wherein said measurement point setting means includes means for applying to said correlation processing means a first signal representing the value of the x-coordinate of the selected measurement point plus a constant value for establishing a window centered on the selected measurement point for determining the length of a data train selected for correlation processing in the determination of the location of said corresponding measurement point in said second image, and a second signal representing the value of the y-coordinate of said selected measurement point.

3. Apparatus for determining the coordinates of a measurement point on a three-dimensional object according to claim 2, wherein said measurement point setting means includes means for selectively adding one of at least first and second different constants to said value of the x-coordinate for establishing one of two or more different window widths.

4. Apparatus for determining the coordinates of a measurement point on a three-dimensional object according to claim 1, wherein said correlation processing means includes circuit means constructed and arranged for performing correlation processing by the Sequential Similarity Detection Algorithm (SSDA) method.

5. Apparatus for determining the coordinates of a measurement point on a three-dimensional object according to claim 1, wherein said correlation processing means includes circuit means arranged for performing correlation processing by the correlation coefficient method.

6. Apparatus for determining the coordinates of a measurement point on a three-dimensional object according to claim 1, wherein said apparatus further comprises illumination means interposed between said first and second photo-electric conversion means for projecting a pattern onto said object.

7. Method for determining the coordinates of a measurement point on a three-dimensional object comprising the steps of:

(a) generating and storing first and second data signals respectively representing first and second images of an object each having a plurality of measurement points and together constituting a stereoscopic image;

(b) adding to the data signal representing said first image signal data signals representing x and y coordinates of a selected measurement point on said object;

(c) by correlation processing finding in said second data signal a measurement point in said second image which substantially corresponds to the selected measurement point in said first image;

(d) adding to the data signal representing said first image a mark data signal representing the location of the selected measurement point and adding a mark data signal to the data signal representing said second image at the location in said second image which corresponds to the selected measurement point in sai first image;

(e) forming from the data signals resulting from step (d) a stereoscopic image of said object;

(f) visually examining said stereoscopic image and determining whether the image of the measurement point in said second image is correctly positioned in the image;

(g) repeating steps (b) through (f) until the image of the measurement point in the second image is correctly positioned in the image; and

(h) then calculating the values of x, y and height (z) coordinates of the selected measurement point from data signals representing said selected measurement point and the measurement point in said second image.