OverviewRealism in image synthesis increases significantly when real-world lighting captured into environment maps (EM) is used to illuminate rendered scenes. Tremendous progress in the development and accessibility of high dynamic range (HDR) video cameras enable direct capturing of HDR video environment maps (VEM). In this work we present an interactive system for fully dynamic lighting of a scene using captured HDR VEM. The key component of our system is an algorithm for efficient decomposition of HDR VEM into a set of representative directional light sources, which can be used for the direct lighting computation with shadows on graphics hardware. The resulting lights have favorable properties in terms of flickering reduction and their number can be adaptively changed to keep a constant framerate while good spatial distribution (stratification) properties are maintained. We can handle a large number of light sources with shadows using novel techniques, which reduce the cost of BRDF-based shading and visibility computations. VEM Decomposition into Directional Light SourcesFor the HDR VEM acquisition we use a photometrically calibrated HDRC VGAx (IMS CHIPS) camera with a fish-eye lens. We decompose each captured EM into a set of directional light sources, which are well suited for the shadow computation and shading using graphics hardware. In our decomposition approach we treat the pixel luminance values in the EM as a discrete 2D probability density function (PDF) and we draw samples (light source directions) from this distribution following procedures established in the Monte Carlo literature. For this purpose we select our inverse transform method [HDS03], which exhibits unique continuity and uniformity properties that are desirable in our application. The method guarantees the bicontinuity property for any non-negative PDF, which means that a small change in the input sample position over the unit square is always transformed into a small change in the resulting position of light source over the EM hemisphere. The uniformity property is important to achieve a good stratification of the resulting light source directions. Lighting: Progressive Refinement and Temporal CoherenceTo temporal flickering in the resulting frames we choose the same set of initial samples over the unit square for each VEM frame, which are then processed using our inverse transform method. Since our emphasis is on interactive applications, we use a progressive sequence of samples in which adding new samples does not affect the position of samples already used for shading computations, while good sample stratification properties are always preserved. We achieve the progressiveness of sampling sequence using quasi-Monte Carlo sequences such as the 2D Halton sequence. We perform Lloyd's relaxation over the initial sample positions in the unit square in a preprocessing step. This allows us to achieve a blue noise sample pattern on the hemisphere.Since even local changes in the EM lead to global changes of the PDF, the direction of virtually...

In rendering of high quality animations that include global illumination, the final gathering and irradiance caching are commonly used. However, the computational cost they incur is high enough to discourage their wide use in production rendering. We introduce a data structure called anchor, which lets us permanently link cache locations to points intersected by their final gathering rays. Consequently, we can cheaply probe and transfer the (ir)radiance by exploiting the temporal coherence of successive animation frames, resulting in half an order of magnitude acceleration and reduced temporal artifacts. Additionally, our anchor structure lets us render moderately glossy surfaces at the cost much lower than the traditional importance sampling techniques. We also describe an efficient, perceptually motivated and independent scheme for limiting the growth in the number of irradiance caches. Finally, an implementation in a practical rendering system is demonstrated.

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