We introduce a new approach for procedural modeling. Our main idea is to select shapes using selection-expressions instead of simple string matching used in current state-of-the-art grammars like CGA shape and CGA++. A selection-expression specifies how to select a potentially complex subset of shapes from a shape hierarchy, e.g. "select all tall windows in the second floor of the main building facade". This new way of modeling enables us to express modeling ideas in their global context rather than traditional rules that operate only locally. To facilitate selection-based procedural modeling we introduce the procedural modeling language SELEX. An important implication of our work is that enforcing important constraints, such as alignment and same size constraints can be done by construction. Therefore, our procedural descriptions can generate facade and building variations without violating alignment and sizing constraints that plague the current state of the art. While the procedural modeling of architecture is our main application domain, we also demonstrate that our approach nicely extends to other man-made objects.

中文翻译：

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过程建模的选择表达式。

我们介绍了一种过程建模的新方法。我们的主要思想是使用选择表达式来选择形状，而不是使用当前最先进的语法（例如CGA shape和CGA ++）中的简单字符串匹配。选择表达式指定如何从形状层次结构中选择形状的潜在复杂子集，例如“选择主建筑立面第二层中的所有高大窗户”。这种新的建模方式使我们能够在全局上下文中表达建模思想，而不是仅在本地运行的传统规则。为了促进基于选择的过程建模，我们引入了过程建模语言SELEX。我们工作的一个重要含义是，可以通过构造来执行重要的约束，例如对齐和相同大小的约束。因此，我们的程序描述可以产生立面和建筑物变化，而不会违反困扰当前技术水平的对齐方式和尺寸限制。尽管体系结构的过程建模是我们的主要应用领域，但我们也证明了我们的方法很好地扩展到了其他人造对象。