ABSTRACT

Identifying urban boundaries involves analysing both the functional and the morphological aspects of urban systems. In this paper, we adopt a purely morphological approach and compare three methods for the morphological delineation of cities. Each method avoids using any predefined quantified threshold (size, distance, built density, etc.) to detect crucial discontinuities in space. The first method identifies Natural Cities by clustering points. The other two are the fractal-based MorphoLim method and the Hierarchical Percolation; both involve transforming the data using a step-by-step dilation process. The three methods are critically compared and illustrated by applications to theoretical urban patterns. We further apply each method to the urban agglomeration of Brussels, the Belgian capital, using different data (building footprints, building centroids and street nodes) and considering two study areas, namely the former province of Brabant and the entire country of Belgium. The results show that it is impossible to draw an unambiguous morphological boundary for an urban agglomeration. Consequently, it is crucial to relate the data used, the size of the study area and the method chosen to the objectives of the delineation.

摘要

确定城市边界涉及分析城市系统的功能和形态方面。在本文中，我们采用一种纯粹的形态学方法，并比较了三种用于城市形态学描绘的方法。每种方法都避免使用任何预定义的量化阈值（大小，距离，内部密度等）来检测空间中的关键不连续性。第一种方法是通过聚类点识别自然城市。另外两个是基于分形的MorphoLim方法和分层渗透; 两者都涉及使用逐步扩展过程来转换数据。对这三种方法进行了严格的比较，并通过理论上的城市模式加以说明。我们使用不同的数据（建筑足迹，建筑质心和街道节点）并考虑两个研究区域，即前布拉班特省和比利时全国，进一步将每种方法应用于比利时首都布鲁塞尔的城市群。结果表明，不可能为城市群画出一个清晰的形态边界。因此，至关重要的是将所使用的数据，研究区域的大小以及所选择的方法与勾画的目标联系起来。