A novel area measurement scheme based on a multi-resolution dynamic contour

A novel scheme for an object's surface area measurement is proposed, which is suitable for area computation of an object with smooth and irregular edges. A multi-resolution dynamic contour is applied and this scheme consists of four steps. Firstly, a photoelectric image collimation system is applied to obtain a target image of a detected object. An image pyramid for the target image is constructed by wavelet decomposition and reconstruction. Secondly, in the image pyramid, a multi-resolution dynamic contour converges to the target's contour edge from coarse to fine scale, via feature search and an iteration algorithm. Thirdly, for the convergent dynamic contour, two formulas for the area and centroid computation of a closed B-spline curve are applied to compute the image target's area and centroid exactly. Finally, a novel centroid self-calibration technology is applied, which measures the pixel's size equivalence with the computed centroid and a dual-frequency laser to measure the true object's surface area exactly. Experiments indicate that this scheme's single-measurement error decreases to ±0.2%, when the number of control points is 20. Compared to conventional measurement approaches, this scheme is robust for a target image with noises or complicated edges.