The Urban Heat Island (UHI) effect, defined as a significant increase in temperature in urban environments compared to surrounding areas, is difficult to study in real cities using sensor data (satellites or in-situ stations) due to their coarse spatial and temporal resolution. Among the factors contributing to this effect are the properties of urban materials, which differ from those in rural areas. To analyze their individual impact and to test new material configurations, a high-resolution simulation at the city scale is required. Estimating the current materials used in a city, including those on building facades, is also challenging. We propose HeatMat, an approach to analyze at high resolution the individual impact of urban materials on the UHI effect in a real city, relying only on open data. We estimate building materials using street-view images and a pre-trained vision-language model (VLM) to supplement existing OpenStreetMap data, which describes the 2D geometry and features of buildings. We further encode this information into a set of 2D maps that represent the city's vertical structure and material characteristics. These maps serve as inputs for our 2.5D simulator, which models coupled heat transfers and enables random-access surface temperature estimation at multiple resolutions, reaching an x20 speedup compared to an equivalent simulation in 3D.

翻译：城市热岛效应是指城市环境温度相较于周边地区显著升高的现象。由于传感器数据（卫星或地面站点）的时空分辨率较低，在真实城市中利用此类数据研究该效应具有挑战性。导致该效应的因素之一是城市材料的特性，这些特性与乡村地区存在差异。为分析其单独影响并测试新的材料配置方案，需要在城市尺度进行高分辨率模拟。同时，准确估算城市现有材料（包括建筑立面材料）也颇具难度。本文提出HeatMat方法，仅依靠开放数据即可在真实城市中高分辨率分析城市材料对热岛效应的单独影响。我们利用街景图像和预训练视觉语言模型估算建筑材料，以补充描述建筑二维几何与特征的现有OpenStreetMap数据。进一步将这些信息编码为一组表征城市垂直结构与材料特性的二维地图。这些地图作为我们2.5D模拟器的输入，该模拟器对耦合热传递进行建模，支持多分辨率随机访问地表温度估算，相比等效三维模拟实现了20倍加速。