Hough transform approach to gap measurement in blade inspection

Two adjacent objects with a gap between the objects rotate in a hot atmosphere with a temperature greater than 300 F in a gas turbine. Automatic and accurate contactless measurement of the gap is performed by taking images of the gap. An image, preferably an infra-red image is taken from the gap, a processor extracts the two edges from the image of the gap. The processor also determines a line through the pixels of an edge by applying a Hough transform on the pixels. The edges are substantially parallel. A line substantially perpendicular to the lines is also determined. Using the substantially parallel lines and the line substantially perpendicular to the substantially parallel lines the processor determines a width of the gap.