Illumination Space: A Feature Space for Radiance Maps

Abstract

From red sunsets to blue skies, the natural world contains breathtaking scenery with complex lighting which many computer graphics applications strive to emulate. Achieving such realism is a computationally challenging task and requires proficiency with rendering software. To aid in this process, radiance maps (RM) are a convenient storage structure for representing the real-world. In this form, it can be used to realistically illuminate synthetic objects or for backdrop replacement in chroma key compositing. An artist can also freely change a RM to another that better matches their desired lighting or background conditions. This motivates the need for a large collection of RMs such that an artist has a range of environmental conditions to choose from. Due to the practicality of RMs, databases of RMs have continually grown since its inception. However, a comprehensive collection of RMs is not useful without a method for searching through the collection.  This thesis defines a semantic feature space that allows an artist to interactively browse through databases of RMs, with applications for both lighting and backdrop replacement in mind. The set of features are automatically extracted from the RMs in an offline pre-processing step, and are queried in real-time for browsing. Illumination features are defined to concisely describe lighting properties of a RM, allowing an artist to find a RM to illuminate their target scene. Texture features are used to describe visual elements of a RM, allowing an artist to search the database for reflective or backdrop properties for their target scene. A combination of the two sets of features allows an artist to search for RMs with desirable illumination effects which match the background environment.