We present an efficient scheme for representing irregular object boundaries which belongs to the grid-based chain coding family. The scheme which is called polycurve codes extends the chain coding family, e.g., chain codes and generalized chain codes, by employing predefined circular-arc segments as boundary approximators in addition to straight-line segments. Each circular-arc segment in polycurve codes is predefined around the associated line segment and labeled as an integer. Polycurve codes enables direct extraction and labeling of high-level line and arc segments from arbitrary boundaries. Once the object boundaries are encoded by poly-curve codes, feature calculation and shape analysis may be done solely based on the look-up table indexed by the integer labels. Experimental results show that polycurve codes improve performance, such as compactness and encoding time, over the existing chain coding family.
Chang Y. Choo, Chang Y. Choo,
"An Efficient Grid-Based Representation Of Arbitrary Object Boundaries", Proc. SPIE 1002, Intelligent Robots and Computer Vision VII, (27 March 1989); doi: 10.1117/12.960265; https://doi.org/10.1117/12.960265