数字地图符号的形状描述与识别

Shape Description and Recognition of Digital Map Symbols

采用地图自动数字化替代既费时又费力的传统手工数字化，是当代地图制图学的一项重要研究内容，而数字地图符号的描述与识别则是实现这一目标的关键技术。为此，本文利用带搜索控制准则的新边界跟踪算法改进了传统的边界跟踪算法，提出了用傅立叶系数描述符号，给出了如何由链码计算傅立叶系数，并对计算公式作了进一步改进，以及由傅立叶系数提取形状特征不变量。最后，对符号识别进行实验验证，并做了相应的分析讨论。

It is an important research content of Cartography to use map automatic digitization instead of old way by hand which is a difficult and time consuming task. The description and recognition of digital map symbols is a key technique to realize this objective. In this paper, a traditional boundary following is improved by using a new algorithm with a criterion to control search. A describes symbols method is proposed by use Fourier coefficient. The way how to calculate these coefficients from chain code is given. Then the calculation formula is further ameliorated. And how to extract shape feature invariant from Fourier coefficient is introduced also. At last some symbols recognition experiments are done, and relevant analysis is discussed.