Method of three-dimensional measurement with few projected patterns

• US 4,648,717 A
• Filed: 11/04/1985
• Issued: 03/10/1987
• Est. Priority Date: 02/06/1984
• Status: Expired due to Term

• Current Assignee: Robotic Vision Systems, Inc. (Omron Corporation)
• Original Assignee: Robotic Vision Systems, Inc. (Omron Corporation)
• Inventors: Schmidt, Richard, Ross, Joseph
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US06/794,613
• Time in Patent Office: 491 Days
• Field of Search: 356/2, 356/375, 356/376, 250/558, 354/77, 354/113
• US Class Current: 356/610
• CPC Class Codes: G01B 11/2536 using several gratings with variable grating pitch, projected on the object with the same angle of incidence

Abstract

Methods are provided for reducing the number of projected patterns required to make two- or three-dimensional surface measurements on a sub-class of surfaces comprising relatively smooth surfaces. By including apriori knowledge about the surface to be measured, pattern ambiguities can be resolved by processing rather than by additional projected patterns.

Claims

1. A method for resolving ambiguity of a periodic pattern projected upon a surface to be measured in two or three dimensions comprising the steps of:

projecting a periodic radiation pattern on a surface and obtaining a first reflected pattern;

recording an image of said first reflected pattern;

projecting one period of said periodic radiation pattern upon said surface and obtaining a second reflected pattern;

recording an image of said second reflected pattern;

identifying said one period image as a reference image; and

identifying each period image sequentially in the periodic image relative to the reference image.

2. A method for resolving ambiguity of a periodic pattern projected upon a surface to be measured in two or three dimensions, comprising steps of:

projecting a periodic radiation pattern with at least one period of a distinguishably different radiation wavelength from the remaining pattern and obtaining therefrom a periodic reflected pattern;

recording an image of said reflected pattern;

identifying the image of said different radiation wavelength period as a reference image; and

identifying an image of each period sequentially in the periodic image relative to the reference image.

3. A method for resolving ambiguity within a periodic pattern projected upon a surface to be measured in two or three dimensions comprising the steps of:

projecting a periodic radiation pattern on a surface, said pattern containing at least one period differing by a known length from the remaining pattern and obtaining therefrom a reflected pattern;

recording an image of said reflected pattern;

identifying said period differing by a known amount as a reference image; and

identifying each period image sequentially in the periodic image relative to the reference image.

4. A method for resolving ambiguity within a periodic pattern projected upon a surface to be measured in two or three dimensions, comprising the steps of:

projecting a periodic radiation pattern having a first and a last period onto a surface such that at least the first or last period is on said surface and obtaining therefrom a periodic reflected pattern;

recording an image of said reflected pattern;

identifying said first or last period as a reference image; and

identifying each period image sequentially in the periodic image relative to the reference image.

5. A method for resolving ambiguity within a periodic pattern projected upon a surface to be measured in two or three dimensions, comprising the steps of:

projecting a periodic radiation pattern on a surface, said pattern containing at least one aperiodic component, and obtaining therefrom a reflected pattern;

recording an image of said reflected pattern;

identifying said aperiodic component as a reference image; and

identifying each period image sequentially in the periodic image relative to the reference image.