Modeling urban environmental quality in a tropical city

Environmental quality is an abstract concept resulting from both human and natural factors operating at different spatial scales. In urban areas the local scale is dominated by individual buildings, streets and trees, but regional scale influences may include the whole city and beyond. This paper demonstrates the ability of current satellite-based sensing systems to depict parameters of urban environmental quality over large areas at detailed level, using 3D Virtual Reality models. A method is described for increasing the spatial detail and spectral accuracy of Landsat ETM+ thermal data, by fusion with an IKONOS image representing vegetation. Additionally, by depicting the complete radiating surface involved in energy exchange between the surface and atmosphere, including vertical walls, as well as the horizontal surfaces ‘seen’ by the satellite, a more accurate representation of the urban thermal environment is obtained. The models permit 3D visualization and fly-through animation to represent urban environmental quality, based on quantifiable image parameters, and assist the understanding of the complex and dynamic factors controlling urban environmental quality.