A Method for Estimating Illumination Distribution of a Real Scene Based on Soft Shadows

This paper describes a new method for estimating an illumination distribution of a real scene. Shadows in a real scene are usually observed as soft shadows that do not have sharp edges. In the proposed method, illumination distribution of the real scene is estimated based on radiance distribution inside the soft shadows cast by an object in the scene. By observing shadows and not illumination itself, the proposed method is able to avoid several technical problems which the previously proposed methods suffered from: how to capture a wide field of view of the entire scene and how to capture a high dynamic range of the illumination. The estimated illumination distribution is then used for rendering virtual objects superimposed onto images of the real scene. We successfully tested the proposed method by using real images to demonstrate its effectiveness.

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