Appearance synthesis of fluorescent objects with mutual illumination effects

Abstract

We propose an approach for the appearance synthesis of objects with matte surfaces made of arbitrary fluorescent materials, accounting for mutual illumination. We solve the problem of rendering realistic scene appearances of objects placed close to each other under different conditions of uniform illumination, viewing direction, and shape, relying on standard physically based rendering and knowledge of the three-dimensional shape and bispectral data of scene objects. The appearance synthesis model suggests that the overall appearance is decomposed into five components, each of which is expanded into a multiplication of spectral functions and shading terms. We show that only two shading terms are required, related to (a) diffuse reflection by direct illumination and (b) interreflection between two matte surfaces. The Mitsuba renderer is used to estimate the reflection components based on the underlying Monte Carlo simulation. The spectral computation of the fluorescent component is performed over a broad wavelength range, including ultraviolet and visible wavelengths. We also address a method for compensating for the difference between the simulated and real images. Experiments were performed to demonstrate the effectiveness of the proposed appearance synthesis approach. The accuracy of the proposed approach was experimentally confirmed using objects with different shapes and fluorescence in the presence of complex mutual illumination effects.