在工程语义分类基础上，首先探讨了3类工程语义的图样理解中的作用和关系，即表达方式工程语义是前提，投影关系工程语义是核心，尺寸约束工程语义是引导；然后，着重介绍了工程语义的分类获取和整合获取技术，包括表达方式、投影关系、尺寸工程主义的分类获取技术，以及相切、相贯、截交工程语义的整合获取技术，并以一系列“元组链”及“约束状态链”的形式对工程语义进行重新组织；最后以一个说明工程语义获取技术在图校理解过程中的应用情况，该方法已成功地应用于作者研制的图样理解原理试验系统，并取得了很好的效果，试验结果表明，该方法不仅可以简化图样理解的复杂程度，还可以提高识别、处理的速度和计算机理解的可靠性。

This paper is concerned with the problem of intelligent understanding of engineering drawing. The presented method is based on the engineering semantics classification. The contribution of different kind of semantics and the relationships among them in engineering drawings understanding are firstly discussed, namely, expression mode semantics is the premise, projection relation semantics is the kernel and dimension constraint semantics is the elicitation. Then the technology of engineering semantics obtaining and the corresponding integration are mainly introduced, thus the functional semantics expressed through the engineering semantics information could be obtained. In the end, complete details are provided to illustrate the identification of simple features and the combined relationship among the primitives using this approach. This method has been successfully used in the prototype system and the expected results have been got. It shows that the drawing understanding could be simplified, the recognition and processing could be speed up, and furthermore, the understanding reliability could be enhanced by using the technology.