Abstract: In this paper we used a model for real objects.By a series of definitions and lemmas，we studied a composition method which was applied to cardinal direction relations based on real objects.According to our study，we put forward a new composition algorithm，which can be used to compose more complex cardinal direction relations of real objects availably.

Key words: minimum bounding box, rectangular relation, single-tile cardinal direction relation

摘要： 使用基于真实物体的方向关系模型，通过一系列的定义和定理，研究了一种基于真实物体的主方向关系的合成方法。在此基础上，提出了一种新的合成算法，该算法能够更有效地合成真实物体间更为复杂的主方向关系。

关键词: 最小边界框, 矩形关系, 单一主方向关系