Patent ID: 8311311

Claim:
A method for correcting at least one Z-height measurement determined by a machine vision inspection system based on a corresponding focus region of interest, to provide at least one corrected Z-height measurement, the method comprising: (a) determining at least one Z-height measurement based on a corresponding focus region of interest; (b) determining orientation angle content characteristics for image content in the corresponding focus region of interest in a sufficiently focused image of the corresponding focus region of interest; (c) accessing Z-height error calibration data that includes a characterization of a variation in Z-height measurement results based on a focus region of interest used for calibration, in relation to a variation in an orientation angle of anisotropic image content in the focus region of interest used for calibration; (d) determining a Z-height error correction value based on the orientation angle content characteristics for the image content in the corresponding focus region of interest and the Z-height error calibration data; and (e) correcting the at least one Z-height measurement using the Z-height error correction value to provide the corrected at least one Z-height measurement.