Procedural Urban Global Illumination

 

In this project we propose the development of new algorithms for global illumination computations in urban environments. This is an extremely complex problem due to the large number of geometrical elements included in each architectonic structure (e.g. buildings). The proposed approach consists of a three pass algorithm, which computes all light transfer between elements in a typical urban scene:
    The first pass computes the sun/sky direct illumination onto the whole city. In particular, here we aim at computing the incident radiance at each building façade, taking into account the high/low frequencies related to the different kinds of illumination (sun light has sharp features which the general illumination form the sky, several order of magnitude smaller, doesn?t)
    The next pass computes the Building-Building (B-B) light propagation, using techniques related to the well known hierarchical radiosity method, but taking into account the procedural nature of state-of-the-art development in urban modeling.
    The last step recovers the shadow information from the sun gathered in the first pass, and combines it with the diffuse illumination computed in the B-B stage plus an ambient occlusion term to model the fine-grained illumination details, to build a full illumination solution for a complete urban environment
During this process we aim at taking into account the physical properties of each kind of interaction by taking advantage of their limited range (energy loss), and combine them with procedural definitions for the architectonic structures, resulting in a fast and practical implementation for the physically accurate simulation of global illumination in urban environments.