Patent ID: 8345333

Claim:
A structural displacement/strain measuring method comprising, the steps of: measuring a predetermined time before and after a time elapse; capturing images of a surface of a to-be-measured object by providing a hand-held line scanner apparatus in close adhesion or in vicinity of the surface of the to-be-measured object; calculating a displacement or strain of the to-be measured object by adapting an image analysis method to the images of the surface of the to-be-measured object captured before and after the time elapse, wherein the image analysis method includes the steps of: determining a first minute area in the image before the time elapse, acquiring a distribution of gradation values in the first minute area, comparing a distribution of gradation values in the image after the time elapse and the distribution of gradation values in the first minute area, and specifying, in the image after the time elapse, a second minute area of which a correlation with the distribution of gradation values in the first minute area is maximized; and shifting the hand-held line scanner apparatus relative to the surface of the to-be-measured object and repeating the calculating step.