DIGITAL IMAGE CORRELATION SYSTEM AND METHOD

摘要

A random speckle pattern is displayed on a display screen and the image then undergoes an imposed geometric transformation, for example being shifted by an integer number of pixels, the pixel pitch having been measured against a standard. The change in the image is measured by a digital image correlation (“DIC”) system, which requires validation. The digital image correlation system is validated by comparing the known measured changes against the imposed geometric transformation. Traceability back to a measurement standard is provided by measuring the pixel pitch with a measuring device that is itself validated back to a measurement standard.

主权项

1. A method of validating a digital image correlation system comprising:
a) displaying a random speckle pattern, as a first image, on a display screen having a stack of a plurality of lines of pixels, adjacent pixels in each line being separated by a known pitch, the pitch having been measured against a standard, b) using the digital image correlation system that requires validation to take a first set of measurements of the random speckle pattern, c) displaying a second image, in which the random speckle pattern of the first image has undergone an imposed geometric transformation, such that one or more blocks of the first image are mapped onto one or more blocks of the second image in a one-to-one mapping, each block being represented on screen as an integer number of pixels, d) ascertaining a measured geometric transformation including taking a second set of measurements with the digital image correlation of the random speckle pattern, and e) comparing the imposed geometric transformation and the measured geometric transformation.