Use of satellite imagery for establishing road horizontal alignments

Generating fast and inexpensive digital road maps and databases from high-resolution satellite imagery is becoming possible for various applications. This paper presents a new method for establishing road horizontal alignment using IKONOS I m spatial resolution imagery. Road extraction algorithms were developed for two types of horizontal curves: Simple circular curves and reverse circular curves. The method requires only two and three unknown parameters for simple and reverse curves, respectively. Unlike existing methods of circle detection, the proposed method performs the search procedures in a much smaller area than the image size and achieves faster computations. The derived curve parameters represent useful inputs into a geographic information system database. The developed method has been tested using IKONOS images for simple and reverse curves. The results show that the proposed method converges in all cases and can be used for accurately establishing road horizontal curves.