An Algorithm for Extracting Contour Lines Based on Interval Tree from Grid DEM

There are two sub-task of automatic contouring from grid DEM.The first is choo-sing a starting cell and the next is the threading process.A new algorithm is proposed based on interval tree to determine starting points of contour lines.The result improves the algo-rithm’s efficiency remarkably.Further,a new strategy is designed to constrain the direction of threading and the resulting contour bears more meaningful information.