We present a new, real-time method for rendering diffuse and glossy objects in low-frequency lighting environments that captures soft shadows, interreflections, and caustics. As a preprocess, a novel global transport simulator creates functions over the object's surface representing transfer of arbitrary, low-frequency incident lighting into transferred radiance which includes global effects like shadows and interreflections from the object onto itself. At run-time, these transfer functions are applied to actual incident lighting. Dynamic, local lighting is handled by sampling it close to the object every frame; the object can also be rigidly rotated with respect to the lighting and vice versa. Lighting and transfer functions are represented using low-order spherical harmonics. This avoids aliasing and evaluates efficiently on graphics hardware by reducing the shading integral to a dot product of 9 to 25 element vectors for diffuse receivers. Glossy objects are handled using matrices rather than vectors. We further introduce functions for radiance transfer from a dynamic lighting environment through a preprocessed object to neighboring points in space. These allow soft shadows and caustics from rigidly moving objects to be cast onto arbitrary, dynamic receivers. We demonstrate real-time global lighting effects with this approach.

Lors de la création d’images de synthèse, le rendu interactif est généralement réalisé avec des modèles d’illuminations simples, le rendu d’images réalistes étant trop lent pour être interactif. Dans cet article, nous proposons une méthode, basée sur le lancer de rayons, qui permet d’obtenir des images réalistes de façon interactive avec un éclairement global. Notre méthode allie le rendu à base d’images (le render cache) à un cache qui résume l’éclairement incident en une source virtuelle (méthode des vecteurs d’éclairement).

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