Vertex Chain Code


The Vertex Chain Code (VCC) is a chain code for representing any two-dimensional (2D) shape composed of regular cells (for instance pixels). This boundary chain code is based on the numbers of cell vertices which are in touch with the bounding contour of the shape. The VCC is invariant under translation and rotation. Also, it may be starting point normalized and invariant under mirroring transformation. Using this concept of chain code it is possible to relate the chain length to the contact perimeter, which corresponds to the sum of the boundaries of neighboring cells of the shape; also, to relate the chain nodes to the contact vertices, which correspond to the vertices of neighboring cells. So, in this way these relations among the chain and the characteristics of interior of the shape allow us to obtain interesting properties. This work is motivated by the idea of obtaining various shape features computed directly from the VCC without going to Cartesian-coordinate representation.


Some important characteristics of the VCC are:

1.      The VCC is invariant under translation and rotation, and optionally may be invariant under starting point and mirroring transformation.

2.      Using the VCC it is possible to represent shapes composed of triangular, rectangular, and hexagonal cells.

3.      The chain elements represent real values not symbols such as other chain codes, are part of the shape, indicate the number of cell vertices of the contour nodes, may be operated for extracting interesting shape properties.

4.      Using the VCC it is possible to obtain relations between the bounding contour and interior of the shape.


The VCC was proposed by E. Bribiesca in 1999.




-Bribiesca E., A New Chain Code, Pattern Recognition. Vol. 32, No. 2, pp. 235-251 (1999).