Accurately mapping urban infrastructure and extent is a high priority for resource management and service allocation as well as for addressing environmental, socioeconomic, and geopolitical concerns. Most available data products only document surficial (two-dimensional) land use and land cover (LULC), yet a substantial component of urban growth occurs in the vertical dimension. Light detection and ranging (lidar) data offer the potential for monitoring three-dimensional (3D) change, but the extreme lack of systematic lidar coverage worldwide inflicts considerable gaps in both spatial and temporal coverage. Satellite scatterometer (radar) data may serve as an alternative data source for characterizing urban growth and development in both the horizontal and vertical directions. The accuracy of these radar-based datasets for estimating building volumes remains to be validated quantitatively. For nine U.S. cities, we test whether scatterometer data can be used to estimate 3D urban built-up volume. We found strong, linear correlations between the lidar-derived and radar-derived building volume estimates for all cities with r² values as high as 0.98 when using spatial trend analysis. Given the high expense that limits lidar data acquisition to small areas at sporadic points in time, satellite scatterometer data provide a breakthrough method for monitoring both vertical growth and horizontal expansion of cities across the world with a continuous decadal time scale.

准确绘制城市基础设施和范围的地图是资源管理和服务分配以及解决环境，社会经济和地缘政治问题的高度优先事项。大多数可用的数据产品仅记录了表面的（二维）土地使用和土地覆盖（LULC），而城市增长的重要组成部分发生在垂直方向。光检测和测距（激光）数据为监视三维（3D）变化提供了潜力，但是全世界极度缺乏系统的激光雷达覆盖范围在空间和时间覆盖范围上都造成了很大的差距。卫星散射仪（雷达）数据可以用作表征水平和垂直方向上的城市增长和发展的替代数据源。这些基于雷达的数据集用于估算建筑体积的准确性仍有待定量验证。对于美国的9个城市，我们测试了散射仪数据是否可用于估算3D城市建筑量。我们发现，对于所有具有r的城市，在激光雷达和雷达衍生的建筑量估算之间存在强烈的线性相关性。使用空间趋势分析时，^两个值高达0.98。鉴于高昂的费用使激光雷达数据的采集只能在零星的时间点进行，因此卫星散射仪数据提供了一种突破性的方法，可以用连续的十年时间尺度监视世界各地城市的垂直增长和水平扩展。