Highway Horizontal Geometric Parameters Calculation from Image Processing

Generating fast and inexpensive digital road maps and databases from high-resolution satellite imagery is becoming possible for various applications. Especially for highway safety evaluation, the highway geometric parameters are the most important. Recently, Google Earth has been in great use in many aspects, and high-resolution images can be easily obtained. The algorithm of road extraction from satellite image has been widely proposed in the world. However, highway features can vary in different resolution aerial images, and even be affected in the same picture by cars and trees. This paper introduces an integrated method of extracting the central dividing strip to get the basic shape of the road and then fitting the discontinuous pixels of centerline as a spline. In the end, the curve radius can be calculated by the tool scale legend given by Google Earth. The program for this study is developed in MATLAB 2009a language under the Windows XP operating system. In accordance with the outcome of experiments, the algorithm proposed here has high precision and a good robustness in different resolutions of pictures.