A robust method for semi-automatic extraction of road centerlines using a piecewise parabolic model and least square template matching

In this paper, we present a semi-automatic road extraction method based on a piecewise parabola model with 0-order continuity. The piecewise parabola model is constructed by seed points coarsely placed by a human operator. In this case, road extraction actually becomes a physical problem of solving of each piece of parabola with only two or three unknown parameters by using image constraints. We have used a least square template matching to solve the parabola parameters. The template is deformable developed based on the automatic detection of dual road edges. In addition, a method of flexible observation weight evaluation has also been developed in this matching method. Extensive testing experiments on various image sets demonstrate that the method is able to extract road centerlines reliably. It offers much higher efficiency in contrast to manual digitizing process. We also discuss some issues about semiautomatic road extraction and future work for improving the reliability and extending the availability of our method.