2D Shape Blending Based on Multi-Level Feature Structures

2D shape blending has been widely used in 2-D character animation,pattern matching,and geometric modeling.Previous algorithms mostly tend to use local geometric elements such as edge lengths,angles and areas,to associate the regions on the two shapes which look alike,but oblivious to the intrinsic feature structures of the shapes.This paper presents a new method that blends planar shapes in terms of their intrinsic feature structures.Firstly,the source and target shapes are decomposed into several pairs of features,respectively,which are further associated via a semi-automatic approach that is based on user's heuristic.Secondly,a multi-level feature structure is defined,representing the global positions and orientations,local orientations,and local details of the shape features.During the shape blending,the feature structure is interpolated from its source to target configurations at each level.Lastly,intermediate shapes are derived from the interpolated results of all levels of the feature structure.Experimental results show that the method can effectively avoid shape distortion and preserve local shape features,as well as generate smooth,natural and visually pleasing effects.