Abstract Since the 1990s, “new urbanism” and “smart growth” have been advocated in the United States, which promote compact urban forms to cope with the environmental and ecological problems caused by urban sprawl. However, there is no uniformity in terms of the spatiotemporal characterization of urban forms. Lack of detailed 3-D urban landscape information makes it difficult to evaluate urbanization trajectories. In this study, we focused on Austin, Texas, U.S., an area with the highest urbanization and the best ranked standard of living, to characterize its evolution of urban morphology and the transformations between urban morphology types (UMTs) over time. We first proposed a conceptual framework to study the UMT transition and urbanization process. Then, the UMT in 2006, 2011 and 2016 was mapped using a synthesis of data sources, which enables a comprehensive understanding of the urbanization process with analytical methods, considering “intensification,” “sprawling expansion,” and “efficient expansion.” Results indicate that Lidar facilitates the multidimensional characterization of urban morphology and its transformation between 2006 and 2016, as maps of UMT were in conformity with the building features of the study area. The urban expansion analysis in different periods (1992–2001, 2001–2006, 2006–2011, and 2011–2016) showed that there has been considerable “intensification” and “efficient expansion” after 2000, indicating the increasingly important role of compact development. In spite of the plans and policies on urban development since the 2000s, we found that there was more sprawl than intensification and efficient expansion. This study demonstrates the advantage of applying Lidar data to characterize urban 3-D morphology and understand its dynamics, which helps develop a comprehensive understanding of the urbanization process and provides a tool for planning intentions and policies evaluation on urban development over time.

中文翻译：

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表征 3-D 城市形态转换以了解城市形态动态：美国德克萨斯州奥斯汀的案例研究

摘要 20世纪90年代以来，美国提倡“新城市主义”和“智能增长”，提倡紧凑的城市形态，以应对城市扩张带来的环境和生态问题。然而，在城市形态的时空特征方面并没有统一。缺乏详细的 3D 城市景观信息使得评估城市化轨迹变得困难。在这项研究中，我们专注于美国德克萨斯州奥斯汀市，这个城市化程度最高、生活水平排名最高的地区，以表征其城市形态的演变以及城市形态类型 (UMT) 随时间的变化。我们首先提出了一个概念框架来研究 UMT 转型和城市化过程。然后，使用综合数据源绘制了 2006、2011 和 2016 年的 UMT，它可以通过分析方法全面了解城市化过程，考虑“集约化”、“蔓延扩张”和“高效扩张”。结果表明，由于 UMT 的地图与研究区的建筑特征一致，因此激光雷达促进了 2006 年至 2016 年城市形态的多维表征及其转变。不同时期（1992-2001、2001-2006、2006-2011和2011-2016）的城市扩张分析表明，2000年后出现了相当大的“集约化”和“有效扩张”，表明紧凑型发展的作用日益重要. 尽管自 2000 年代以来就有了城市发展的规划和政策，但我们发现，蔓延多于集约化和有效扩张。