α-shape地图虚线识别α取值研究

Reconstructing Curves in Form of Non-Continuous Map Lines Using a-shape

给出了一种算法,适用于不光滑、由多条线组成、闭合或不闭合等特点的虚线实体的采样条件.根据采样条件所得的点集P,用合理的α值生成α-shape,再根据地图语义对其进行调整,最后实现地图虚线实体的自动识别.α值与符号识别的正确性关系密切,而α值又与地图比例尺相关,通过实验统计,得到了α值与符号识别采样规则两者间的关系模型.

A new sampling condition that could be satisfied with non-smooth, disjoint, open or closed curves was formulated. However, the sampling condition can't be simply used in the ordinary algorithms. An algorithm was constructed, which can satisfy the sampling condition. Firstly, the algorithm produce the a-shape of the sample points set P with a special a value. The shape was justified by making use of the cartographic semantics. Finally, an acceptable reconstruction was obtained for any collection of the curves in form of non-continuous lines. It should be noticed that the a value corresponding to the set P is important for producing a correct reconstruction. The a value depends on the map scale. A statistical method that establishes a relationship between the a value and the map scale was presented.