The digital process of Building Information Modeling (BIM) involves the creation and modification of CAD-based building models. The complexity of such models has been increasing steadily within the last few years. BIM Models are usually being exchanged using open and standardized data formats. In this context, the Industry Foundation Classes (IFC) are widely used. Therefore, software vendors provide interfaces for dealing with the IFC format. To obtain a high level of data integrity, however, IFC elements are often managed as completely distinct entities, which can result in the creation of multiple copies of identical pieces of information. Since the trend to provide web-based solutions for BIM applications is also becoming increasingly important, especially the conflict between available resource consumption and suitable response times must be considered. Although existing optimization algorithms can reduce the size of an IFC file by analyzing its structure syntactically, there is still the gap to detect identical pieces of geometries that are syntactically distinct. Also, when subsequently merging such geometries, the available sharing concepts must be questioned. The contribution of this paper is twofold. On the one hand, we propose an algorithm to retrospectively detect identical geometries by estimating the rigid body transformation. On the other hand, we outline and evaluate the available possibilities for sharing geometries within the IFC data model. The so-called flyweight pattern is applied to provide and maintain the appropriate reuse of identical information. The methodologies are exemplary demonstrated by modeling and optimizing a typical tunnel lining structure, which contains many repetitive elements. As a result, a noticeable reduction of storage and processing time can be measured. Establishing BIM in large building projects, where complexity not only depends on variation and geometric detail, but also depends on enormous repetition of these elements, a significant benefit is expected.

中文翻译：

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使用刚体变形估计和飞重设计模式消除IFC模型中的重复几何

建筑信息模型（BIM）的数字化过程涉及基于CAD的建筑模型的创建和修改。在过去几年中，此类模型的复杂性一直在稳定增长。通常使用开放和标准化的数据格式交换BIM模型。在这种情况下，广泛使用了行业基础类（IFC）。因此，软件供应商提供用于处理IFC格式的接口。但是，为了获得高水平的数据完整性，通常将IFC元素作为完全不同的实体进行管理，这可能导致创建相同信息的多个副本。由于为BIM应用程序提供基于Web的解决方案的趋势也变得越来越重要，特别是必须考虑可用资源消耗与适当响应时间之间的冲突。尽管现有的优化算法可以通过句法分析IFC文件的结构来减小其大小，但是仍然存在检测语法上不同的相同几何图形的差距。另外，当随后合并这些几何时，必须质疑可用的共享概念。本文的贡献是双重的。一方面，我们提出了一种通过估计刚体变换来追溯检测相同几何形状的算法。另一方面，我们概述并评估了在IFC数据模型内共享几何的可用可能性。所谓的flyweight模式用于提供和维护相同信息的适当重用。通过建模和优化包含许多重复元素的典型隧道衬砌结构，对方法进行了示范性演示。结果，可以测量出存储和处理时间的显着减少。在大型建筑项目中建立BIM，因为其复杂性不仅取决于变化和几何细节，还取决于这些元素的大量重复，因此有望带来显着的收益。