A Tool to Create Illuminant and Reflectance Spectra for Light-Driven Graphics and Visualization

Full spectra allow the generation of a physically correct rendering of a scene under different lighting conditions. In this article we devise a tool to augment a palette of given lights and material reflectances with constructed spectra, yielding specified colors or spectral properties such as metamerism or objective color constancy. We utilize this to emphasize or hide parts of a scene by matching or differentiating colors under different illuminations. These color criteria are expressed as a quadratic programming problem, which may be solved with positivity constraints. Further, we characterize full spectra of lights, surfaces, and transmissive materials in an efficient linear subspace model by forming eigenvectors of sets of spectra and transform them to an intermediate space in which spectral interactions reduce to simple component-wise multiplications during rendering. The proposed method enhances the user's freedom in designing photo-realistic scenes and helps in creating expressive visualizations. A key application of our technique is to use specific spectral lighting to scale the visual complexity of a scene by controlling visibility of texture details in surface graphics or material details in volume rendering.