Abstract: To deal with the matching of 3D terrains which involves similar transformations of scale, rotation, and shift, a terrain contour matching approach based on the invariant feature description of a 3D terrain is proposed. The concavoconvex feature of a 3D terrain is analyzed first, and then the shape of the terrain is represented by an invariant feature vector which describes the relative position distribution of the vertexes. The feature vector is formed by the distances from the local convex points to the reference convex point in the normal direction and tangent direction of the terrain surface around the reference convex point. The terrain matching approach is realized by calculating and comparing the distances of feature vectors which is robust for the similarity transformation of the terrain. The describing and matching method of a 3D terrain is independent with its absolute scale. The simulated experiments prove the validation of the algorithm. It is suitable for the matching of scaled terrain for navigation.

Key words: navigation, terrain contour matching, similarity transformation, terrain feature, feature description