Evaluation of the urban heat island effect based on 3D modeling and planning indicators for urban planning proposals

Urban planning plays an important role in the formation of urban space and microclimate. As a middle-level planning in the Chinese urban planning system, regulatory planning has a direct impact on the shaping of 3D urban space and can maximize the operability of urban planning. However, 3D space formation is not considered in the present preparation of regulatory plans, which leads to a misunderstanding of possibly formed 3D landscapes and microclimatic effects after the plan implementation. To support 3D visualization and quantitative analysis of the urban heat island effect (UHI) for regulatory planning, this study proposes a rule-based 3D modeling method to efficiently generate 3D models. The main elements of 3D models (terrain, building, road, vegetation, and land parcel) and their content were determined after analyzing the characteristics of 3D models in the regulatory plan. The 3D modeling process was constructed and combined with an UHI evaluation model through CGA programming. An index called heat island potential (HIP) was used as the UHI evaluation index and can be quantified using the correlation equations between planning indicators and HIP. The proposed method can support the planners to generate 3D models for a planning proposal, and simultaneously analyze 3D spatial effect and UHI.