Mean radiation temperatures (MRTs) have gained widespread attention due to its close relationship with human health. Notwithstanding the availability of existing methods for evaluating MRT (such as ground-based measurements and numerical simulations), it remains a challenge to rapidly and accurately acquire MRTs with a high spatial resolution. This study thus proposed an efficient methodology for evaluating spatial MRTs of urban spaces on the microscale through multimodal images derived from unmanned aerial vehicles (UAVs). Based on UAVs and near-ground measurements, point-cloud data characterizing long- and short-wave irradiance from three-dimensional (3D) surfaces were obtained via photogrammetry and retrieval models. Spatial MRTs were then sampled based on a mapped 3D radiation field and ray-tracing. Comparison of the sampled MRTs with measured MRTs (near the ground) through globe temperatures exhibited a high consistency (: 0.980, RMSE: 3.080 ) and a small difference (almost less than 2.5 ), demonstrating the applicability and accuracy of our proposed method. In conjunction with near-ground meteorological variables, outdoor thermal comfort (OTC) indicators with a high spatial resolution were derived; further comparisons suggested the SET* and UTCI as ideal indicators to evaluate microscale OTC of hot and humid areas through our method. From the perspective of application, this method can further refine the assessment of the urban thermal environment as well as the human thermal comfort of micro-scale spaces based on simulations or remote sensing observations with lower spatial resolution, which will provide specific suggestions for redesign or redevelopment of the micro-scale areas. Additionally, the thermal mapping with high spatial resolution obtained by this method can also be used as a reference to evaluate the accuracy of related numerical models.

中文翻译：

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如何利用无人机多模态图像快速绘制高分辨率的室外平均辐射温度图：以广州为例

平均辐射温度（MRT）因其与人类健康的密切关系而受到广泛关注。尽管已有评估 MRT 的现有方法（例如地面测量和数值模拟），但快速准确地获取具有高空间分辨率的 MRT 仍然是一个挑战。因此，本研究提出了一种通过无人机（UAV）获得的多模态图像在微观尺度上评估城市空间的空间MRT的有效方法。基于无人机和近地测量，通过摄影测量和检索模型获得了表征三维（3D）表面长波和短波辐照度的点云数据。然后根据映射的 3D 辐射场和射线追踪对空间 MRT 进行采样。通过地球温度将采样的 MRT 与测量的 MRT（接近地面）进行比较，表现出较高的一致性（0.980，RMSE：3.080）和较小的差异（几乎小于 2.5），证明了我们提出的方法的适用性和准确性。结合近地气象变量，推导出高空间分辨率的室外热舒适（OTC）指标；进一步的比较表明 SET* 和 UTCI 是通过我们的方法评估湿热地区微尺度 OTC 的理想指标。从应用角度来看，该方法可以基于较低空间分辨率的模拟或遥感观测，进一步细化城市热环境以及微尺度空间的人体热舒适度评估，为重新设计或改造提供具体建议。微观区域的重建。此外，该方法获得的高空间分辨率热图也可以作为评估相关数值模型精度的参考。