Feature-based parametric modeling is the de facto standard in CAD. Boundary representation-based direct modeling is another CAD paradigm developed recently. They have complementary advantages and limitations, thereby offering huge potential for improvement towards an integrated CAD modeling scheme. Most existing integration methods are developed by industry and typically treat direct edits as pseudo-features, where little can be said about seamless integration. This paper presents an alternative method for seamless parametric/direct integration, which allows parametric and direct edits to work in a unified way. The fundamental issues and challenges of parametric/direct integration are first explained. A framework is then proposed to handle those information inconsistencies, based on a detection-then-resolution strategy. Algorithms that can systematically detect and resolve all possible types of information inconsistencies are also given to implement the framework. With them, model validity can be maintained during the whole model editing process, and then the discrepancy between direct edits and parametric edits can be resolved. The effectiveness of the proposed approach has been shown with a series of case studies and comparisons, based on a preliminary prototype.

翻译：以地貌为基础的参数模型是CAD中事实上的标准。以边界代表为基础的直接模型是最近开发的另一个CAD模式,它们具有互补的优势和局限性,因此为改进综合的CAD建模计划提供了巨大的潜力。大多数现有的集成方法都是由工业界开发的,通常将直接编辑视为假的特征,对无缝整合几乎没有什么可言。本文提出了无缝的参数/直接集成的替代方法,使参数/直接编辑能够以统一的方式运作。首先解释了参数/直接集成的根本问题和挑战。然后提出了一个框架,以根据探测后分辨率战略处理这些信息不一致的问题和挑战。还给执行框架提供了能够系统探测和解决所有可能类型的信息不一致的解算方法。有了这些方法,在整个模型编辑过程中可以保持模型的有效性,然后可以解决直接编辑和参数编辑之间的差异。拟议的方法的有效性通过基于初步原型的一系列案例研究和比较得到证明。