方向概念的模糊性和空间数据固有的不确定性导致了方向关系的复杂性, 在空间关系描述和推理研究中需要考虑空间数据的不确定性和方向概念的模糊性。在四方向模型中各方向片是等角划分; 在八方向模型中4个主要方向片各占60°, 4个次要方向片各占30°。利用区间二型模糊集理论建立了顾及参考点点位误差的八方向模糊不均匀划分模型, 基于区间二型模糊集讨论了方向主隶属度成员函数和隶属度的不确定性。对比分析了八方向模糊不均匀划分模型与锥形模型的区别, 讨论了具有点位误差的参考点与线和多边形的方向关系计算过程, 通过两个实例分析了该模型的特点和点与多边形方向关系的确定方法。

It is necessary to consider the uncertainty of spatial data and fuzziness of relative conception when discussing the description of spatial relation and reasoning because of the complexity of direction relation induced by the fuzziness of direction concept and inherent uncertainty of spatial data. Two fuzzy models are introduced based on classical fuzzy set. In 4-directions fuzzy model the space is divided into four cardinal directions and each direction has equal angle, but each main cardinal direction has 60° and each secondary cardinal direction has 30° in 8- directions fuzzy asymmetric model. Extended 8-directions fuzzy asymmetric model is introduced based on interval type-2 fuzzy sets which takes the positioning error of reference point into account. The primary membership function and the uncertainty of primary membership grade is discussed too. The difference between this model and the cone-based model is comparatively analyzed. Two cases are provided in the last. The first case is used to analysis the attributes of 8- directions fuzzy asymmetric model and the second case shows the process of determining the direction rela-tion between point with positioning error and polygon.