Image registration based on rectangle pattern

To against the complexity in finding feature-pair in image registration caused by traditional features: corners, lines and image edge, a novel method for image registration based on rectangle pattern is proposed. Unlike traditional features, a rectangle pattern can be described as its four vertexes and center, which can afford five pair-wise points for any kind of image transformation, and it holds stable in different weather condition, time and imaging way, which formed by building angular, widely found in aero-image. Firstly, image edge is detected by canny, and then distance transform is applied on the result of canny, by follows, a thresholding and mask convoluting are used on the distance transform result to avoid the interfering complex lines and edge. The center of the rectangles is obtained by clustering on the prior result, and then the four vertexes is calculated by geometric restrict on rectangle pattern. Consequently, we calculate the centers pair of the rectangles by their slope difference which aims to get the correct pair-wise points set between two images. Finally, we use the four vertexes pair and center pair of the rectangle pattern as the input of RANSAC algorithm, to solve an affine transform. The proposed algorithm is proved to be effective and accurate on the translation, rotation and scale between electro-optic(EO) images pair and SAR-EO images pair. 1.3 pixels of registration accuracy result is obtained in the experiment.