Contour Line Tracing Algorithm for Digital Topographic Maps

Topographic maps contain information related to roads, contours, landmarks, land covers and rivers etc. For any Remote sensing and GIS based project, creating a database using digitization techniques is a tedious and time consuming process especially for contour tracing. Contour line is very important information that these maps provide. They are mainly used for determining slope of the landforms or rivers. These contour lines are also used for generating Digital Elevation Model (DEM) for 3D surface generation from any satellite imagery or aerial photographs. This paper suggests an algorithm that can be used for tracing contour lines automatically from contour maps extracted from the topographical sheets and creating a database. In our approach, we have proposed a modified Moore’s Neighbor contour tracing algorithm to trace all contours in the given topographic maps. The proposed approach is tested on several topographic maps and provides satisfactory results and takes less time to trace the contour lines compared with other existing algorithms.