Image-Based Rendering of Synthetic Diffuse Objects in Natural Scenes

We present a method for solving the global illumination problem for synthetic diffuse objects. The approach generates realistic shading for applications where a synthetic object is to be inserted in a natural scene. Using only a few images of the surroundings of the object, we first build an environment map for representing the ambient light. We then model the global illumination integral using Chebyshev polynomials. We show that due to the orthogonality of 2D Chebyshev moments, the global illumination integral can reduce to the inner product of two vectors, representing the irradiance and the bidirectional reflectance distribution function (BRDF). The Chebyshev moments of these two functions are computed off-line and stored in the memory. The rendering of the object in the scene then becomes a simple problem of computing the inner product of the two vectors for each point