TIPS: On finding a tight isothetic polygonal shape covering a 2D object

Abstract

The problem of constructing a tight isothetic outer (or inner) polygon covering an arbitrarily shaped 2D object on a background grid, is addressed in this paper, and a novel algorithm is proposed. Such covers have many applications to image mining, rough sets, computational geometry, and robotics. Designing efficient algorithms for these cover problems was an open problem in the literature. The elegance of the proposed algorithm lies in utilizing the inherent combinatoral properties of the relative arrangement of the object and the grid lines. The shape and the relative error of the polygonal cover can be controlled by changing the granularity of the grid. Experimental results on various complex objects with variable grid sizes have been reported to demonstrate the versatility, correctness, and speed of the algorithm. © Springer-Verlag Berlin Heidelberg 2005.