Method and apparatus of determining the center of area or centroid of a geometrical area of unspecified shape lying in a larger x-y scan field

• US 4,219,847 A
• Filed: 02/22/1979
• Issued: 08/26/1980
• Est. Priority Date: 03/01/1978
• Status: Expired due to Term

• Current Assignee: National Research Council Canada
• Original Assignee: Canadian Patents and Development Limited
• Inventors: Pinkney, Harold F. L., Perratt, Charles I.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Coles, Edward L.
• Application Number:
  US06/014,207
• Time in Patent Office: 551 Days
• Field of Search: 358/125, 358/126, 358/105, 250/203 CT, 364/550, 364/564, 364/559, 244/3.16
• US Class Current: 348/172
• CPC Class Codes: B25J 19/023 including video camera means
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: G06T 7/66 of image moments or centre of gravity

Abstract

A method of obtaining on-line data useful in determining the center of area or centroid of a geometrical area of unspecified shape lying in a larger x-y scan field and having its existence indicated by a level discriminated amplitude or intensity or a parameter measurable in the z-dimension comprising; scanning the x-y field in a known raster pattern and obtaining a series of discrete output voltage pulses related to elemental x-y points in the scan field and having an amplitude related to the amplitude or intensity of the said parameter; generating a series of discrete clock pulses related to elemental x-y points in the scan field; obtaining a series of x and y synchronizing pulses from and related to the x-y scan field; establishing in relation to the clock pulses and the x and y synchronizing pulses a smaller x-y scan field in the form of a rectangular window around the geometrical area in the larger x-y scan field, the boundaries as x-y co-ordinates of the said window being known; identifying, from the series of discrete clock pulses, those pulses that coincide with pulses obtained above having an amplitude above a preset voltage level and which fall within the boundaries of the smaller x-y scan field such as to define sample point areas in the geometrical area; making an overall count of the number of pulses identified above, making a count of the number of elemental x-y point each of the pulses identified above are spaced from a boundary of the window in both the x and the y directions to provide x-moment arm counts and y-moment arm counts, and summing the x-moment arm counts and the y-moment arm counts, said counts taken with the count obtained from above providing data for computing the center of area or other mathematical functions of the geometrical area.

Claims

1. A method of obtaining on-line data useful in determining the center of area or centroid of a geometrical area of unspecified shape lying in a larger x-y scan field and having its existence indicated by a level discriminated amplitude or intensity or a parameter measurable in the z-dimension comprising:

(a) scanning the x-y field in a known raster pattern and obtaining a series of discrete output voltage pulses related to elemental x-y points in the scan field and having an amplitude related to the amplitude or intensity of the said parameter;

(b) generating a series of discrete clock pulses related to elemental x-y points in the scan field;

(c) obtaining a series of x and y synchronizing pulses from and related to the x-y scan field;

(d) establishing in relation to the clock pulses and the x and y synchronizing pulses a smaller x-y scan field in the form of a rectangular window around the geometrical area in the larger x-y scan field, the boundaries as x-y co-ordinates of the said window being known;

(e) identifying, from the series of discrete clock pulses, those pulses that coincide with pulses obtained in (a) having an amplitude above a preset voltage level and which fall within the boundaries of the smaller x-y scan field such as to define sample point areas in the geometrical area;

(f) making an overall count of the number of pulses identified as in (e);

(g) making a count of the number of elemental x-y point each of the pulses identified in (e) are spaced from a boundary of the window in both the x and the y directions to provide x-moment arm counts and y-moment arm counts; and

(h) summing the x-moment arm counts and the y-moment arm counts, said counts taken with the count obtained from (f) providing data for computing the center of area or other mathematical functions of the geometrical area.