Three-dimensional visualization of thermal environments in urban canyons

Temperature distribution in urban canyons is dynamic, complex, and influenced by a range of heat resources such as radiant heat from reflected sunlight and convective heat from wind flow. While 2D data collection and presentation are the norm for UHI research, we propose using an unmanned aerial vehicle to measure temperatures at different horizontal and vertical locations in urban canyons to develop a 3D visualization of urban thermal environments. We implemented Gestalt laws and transparent and opaque color-coding to improve background recognition and visual closure as well as to better represent the spatiality of temperature data. Our design included grouped color pixels and an interactive temperature slider function. We investigated whether interface usage varied with the flexibility of closure, perceptual speed, and spatial relations of users. Responses from 102 participants indicated that users with flexibility in closure approved of the transparent colors and slider. The primary advantage of this visual model is the elimination of clutter. Visual clutter can cause users to lose their focus when searching a 2D representation of a 3D geographic space. In the proposed model, data hotspots and the boundaries produced by multiple aggregations and clustering enable users to readily and easily find the required information.城市峡谷(urban canyon)内的温度分布兼具动态性与复杂性，其受多种热源影响，包括反射太阳光产生的辐射热与气流带来的对流热。尽管二维数据采集与展示是城市热岛(Urban Heat Island, UHI)研究的常规范式，但本研究提出采用无人机(unmanned aerial vehicle, UAV)对城市峡谷内不同水平与垂直位置的温度进行测量，以此构建城市热环境的三维可视化模型。本研究应用格式塔(Gestalt)法则，结合透明与不透明色彩编码，以提升背景识别度与视觉闭合性，同时更精准地呈现温度数据的空间属性。本次可视化设计包含分组色彩像素与交互式温度滑块功能。本研究探究了界面使用行为是否会随用户的闭合灵活性、感知速度以及空间认知关系产生差异。102名参与者的反馈表明，具备闭合灵活性的用户对透明色彩编码与滑块功能更为认可。该可视化模型的核心优势在于消除了视觉杂乱问题。在对三维地理空间的二维展示进行信息检索时，视觉杂乱会使用户分散注意力，难以专注于信息查找。本模型中的数据热点以及经多次聚合与聚类生成的边界，可帮助用户快速且轻松地定位所需信息。