A Ray-Traced Sampling Framework for Visualizing and Improving Material Detail in Urban Energy Simulations with QUIC EnvSim

Abstract

Materials such as concrete, asphalt and red brick replacing vegetation have given rise to the Urban Heat Island phenomenon. The Urban Heat Island phenomenon is when the temperature of the region within the cities is higher compared to the rural surroundings, often resulting in higher energy costs. With urbanization being very common, this problem needs to be addressed now more than ever. With QUIC EnvSim, we are able to simulate and better understand energy balance in urban settings. However, QUIC EnvSim does not represent building material properties in fine-grained detail and is limited by the level of discretization of the urban domain. Due to the nature of solar energy simulations, the level of details in the scene can potentially have a large impact on the energy calculations. The hypothesis that this thesis works on is that adding micro level material details to buildings at a scale smaller than the domain discretization, will affect the energy balance calculations in the urban environment. This paper extends on QUIC EnvSim(QES) which is an extendable framework for urban climate modeling. The newly developed model improves on the visual aspects of the frameworks, making the scenes more realistic. It provides the option to choose from various types of buildings in the urban environment. Building type can be either fixed or be randomly assigned based on the settings specified in the configuration. Apart from improving the visual aspect, the new model also uses this visual information for more detailed calculation of material properties such as albedo, emissivity, and diffuse fraction. The model can be enhanced by defining additional building types, resulting in more complex and detailed scenes. The system uses OptiX for visualizing the models. The OptiX Ray tracing engine is an accessible, flexible and reusable platform used for development of ray tracing programs for NVIDIA GPUs. The model is used to visualize complex scenes such as the University of Minnesota, Duluth and downtown Salt Lake City, Utah. The results provide better visuals and also provide more accurate estimation of the energy balances in the urban environments. Simulations using the old and the new system were run over the course of three days for a street in Gothenburg, Sweden, for which data has been measured experimentally. The comparison of the results show that adding material details into the scene improved on the results by taking them closer to the measured values.