Algorithms for Building TIN-based DEM Based on Terrain Feature Lines

For the plane triangle in building irregularly triangle net(TIN)of DEM,some new algorithms are put forward to eliminate plane triangle.The algorithms include auto-adding characteristic points and approximating important characteristic points by Lagrange interpo-lation polynomial.On the other hand,the practicability and validity of the algorithms are validated by contours reconstructed.The experiments show that the proposed algorithm can eliminate plane triangle and optimize the structure of TIN.