Extraction of Roads from Remotely Sensed Images using a Multi-Angled Template Matching Technique

The extraction of road networks from satellite or aerial images has profound applications in the fields of urban planning, setting up of transportation networks, disaster management, cartography and in Geographical Information Systems. In this paper, we have developed a multi-shaped and multi-angled template matching algorithm in order to extract the road network from medium and high-resolution satellite images. We used a quadruple orthogonal line filter to extract lines from four different directions. Small isolated points and edges are removed using appropriately designed clearing filters. Gaps in the road network are bridged using our edge linking algorithm, which is based primarily on the spectral property of the original image pixels. The four images are cleared again using directional clearing filters to remove broken edges that cannot be linked to the road network. Finally, the output from these four separate images are fused into a single image in order to get the final output image which represents the road network. The results obtained demonstrate the practicability of our proposed method in rural and semi-urban regions.