Surface topography with moiré by image processing. Estimation of local line curvature for the description of back shape

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Abstract

An image analysis software package (SIS) was used to realize a projected moiré method on a PC/framegrabber combination. Video sequences were studied using a camcorder. A CCD camera was also used for evaluating paper prints or film negatives obtained from photographic moiré. The essential steps of image processing were: multiplying the reference grid with the distorted line image and Sobel filtering. Anatomical landmarks, or predefined points on the moiré fringes were marked interactively; from the binarized image, coordinates were extracted directly, or transferred to AutoCAD. An estimate of fringe curvature by way of three-point-reconstruction of arcs thus became possible, but was also accomplished with the measurement functions of the image analyzer. The method's reduced sensitivity makes it robust and versatile, but quite capable of quantitative studies on the body surface, with the subject in a position at will. Examples suggest that the method may be useful for a more rational understanding of physiotherapeutic effects.

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Over : Haymo Kurz

Over : Ortwin Leder