Patent ID: 7920982
Filing Date: 2011-04-05
Classification: G01M,G02B,H04N

Abstract:
1. A method of performing distortion calibration for an electro-optical sensor, comprising: a) providing a physical target pattern having a plurality of physical targets and a reference; b) optically projecting the target pattern so that the pattern may be shifted in a sensor field-of-view (FOV) measured by the sensor while preserving relative positions of the targets and the reference; c) moving the target pattern about the sensor FOV over a plurality of frames; d) passing the projected target pattern through sensor optics that introduce non-linear distortion to the projected target pattern, said sensor optics' non-linear distortion producing apparent differences in the relative positions of the targets as the target pattern moves; e) observing a reference position of the reference in said plurality of frames; f) observing target positions of the targets in the sensor FOV in said plurality of frames; g) applying a function F representative of the distortion of the sensor optics to the observed target and reference positions to provide corrected target and reference positions; h) representing corrected difference positions for a plurality of the targets as a difference between the corrected target positions and the corrected reference position; i) fitting coefficients for the function F using the observed target and reference positions over a subset of the targets and frames to minimize the scale-normalized variability of the corrected difference positions as the targets move across the FOV; and j) storing the coefficients in a tangible medium of the sensor as calibration terms for the sensor.