A Hierarchical Method of Recognizing Plant Species by Leaf Shapes

In order to recognize plant species from their shapes, shapes of contours of leaves can be used. However, contours of leaves are complicated and have variations. In order to deal with the complexities and variations of contours of leaves, a hierarchical representation of leaves is presented in this paper. First, global structures and shapes of leaves are represented by polygons whose vertices are critical points of curvature of smoothed contours of leaves. Second, detailed shapes of mid-most pieces are represented by linear approximation of the contours of pieces. Last, teeth on the contour of leaves are represented by triangles. Such triangles are detected from contours tha t are not smoothed enough to remove teeth. Features a t each hierarchy are represented statistically. Such a hierarchical representation is more powerful than previous methods that represent only global structures of leaves.