空间方向关系是描述空间目标间位置分布的一类基本空间约束，在GIS中是由形式化模型描述的。但现有模型由于简化假设过多，其描述分辨率较低。以点／点空间方向关系的计算量为基础，在综合考虑空间目标的几何构成和分布关系后，提出了定量化演算空间方向关系的一种新模型。利用该模型的结果，根据定量表达与定性描述之间的转换函数，可以得到相应的定性描述结果。理论分析和算例表明，新模型对目标间距离和目标本身的形状等影响方向关系的参数更为敏感，因而比现有模型有更高的描述分辨率。

As one of the basic constraints in geographical space, spatial direction relation represents geometric distribution relations of spatial objects and is described and operated by formal models in GIS. However, the existing models are incapable of distinguishing variations between two direction relations of complex objects. This paper aims to develop a computational model with high resolution in identifying the effect of parameters such as distance and shape of spatial objects on their direction relations. First, a generic quantitative approach on direction relations was proposed on the basis of the classical computation of point/point relations, in which both geometric structures and relative distribution relations of spatial objects were utilized. To obtain a reasonable qualitative description, the conversion function was further developed to link the quantitative computation with qualitative description of spatial direction relations. Numerical examples were also provided to demonstrate how to apply the proposed model into practice. Both theoretical comparison and numerical analysis indicated that the model presented in this paper is more sensitive to the parameters such as shape, size and location of spatial objects, and thus is more accurate in distinguishing different direction relations. In particular, the resulting direction relations obtained from the model satisfy three basic cognitive characteristics, including continuity, reflectivity, and asymmetry.