Patent ID: 8773526

Claim:
A method for determining a location of an edge feature of a three-dimensional workpiece using a machine vision inspection system, wherein the machine vision inspection system comprises a control system, a light stripe projection system, an imaging system, and a user interface usable to define a sequence of operations usable to determine the location of the edge feature, the method comprising: (a) positioning the edge feature of the three-dimensional workpiece in a field of view of the machine vision inspection system; (b) focusing the imaging system at an imaging focus plane at a height corresponding to the edge feature; (c) defining a region of interest including the edge feature using the user interface; (d) determining an edge direction corresponding to a direction along the edge feature in the region of interest; and (e) determining the edge feature location, wherein determining the edge feature location comprises: (e1) operating the light stripe projection system to project at least one light stripe having a longitudinal axis oriented transverse to the determined edge direction in the region of interest, and extending across the edge feature; (e2) operating the light stripe projection system to focus the at least one light stripe at a light stripe focus plane at a height corresponding to the edge feature such that a surface height change across the edge feature causes a changing light stripe intensity profile along the light stripe due to defocus, which varies with the edge feature surface height along the light stripe without changing the orientation of the longitudinal axis of the light stripe; (e3) operating the imaging system to acquire an image of the at least one light stripe at the imaging focus plane; and (e4) analyzing the acquired image of the at least one light stripe in the region of interest and determining the location of at least a portion of the edge feature based on a changing characteristic of the changing light stripe intensity profile along the at least one light stripe.