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Instant Radiosity

Explore the Instant Radiosity algorithm with Quasi-Monte Carlo integration, particle approximation, and specular effects for efficient global illumination rendering. Enhance realism in interactive applications.

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Instant Radiosity

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  1. Instant Radiosity Alexander Keller University Kaiserslautern Present by Li-Fong Lin

  2. Outline • Global Illumination • Quai-Monte Carlo Integration • Algorithm • Extensions • Reasults

  3. Global Illumination • Radiance equation : • Shorthand : • In the radiosity setting, restricted to only diffuse reflection :

  4. Global Illumination • Detector functional Ψ: the sum of orthonormal base vectors of a finite vector space. • Directly select the function below in this paper

  5. Global Illumination • In realistic applications : ||Tfr|| < 1, less than 100% of the incident radiance is reflected. • So the Neumann series converges and can be used to solve the integral equation.

  6. Quasi-Monte Carlo Integration • Replace the random numbers used in standard Monte Carlo with low-discrepancy points. • Much smoother convergence at a slightly superior rate. • Halton sequence is used in this paper.

  7. van der Corput sequence

  8. Algorithm • Approximate the radiance L in the radiosity setting by a discrete density of M point light sources. • The particle approximation yields the very fast rendering algorithm: Pi Pi L(y) Pi Li y

  9. Algorithm • Only small deviation from mean reflectivity in realistic scene models. • We can use fractional absorption and avoid Russian Roulette absorption. • ρN particles will survive after one reflection.

  10. Algorithm • The Quasi-Random Walk • Evaluate TmnLe using N point lights, TmnTfdLe by using ρN point lights, and so on. • Finally the quasi-Monte Carlo integration is performed by accumulating all images with the weight 1/N

  11. Pseudo-Code

  12. Extensions • Jittered Low Discrepancy Sampling

  13. Extensions • Specular Effects • By a random decision each surface is tested to be specular or diffuse according to its BRDF. • Mirror the origin ray by the specular surface. • Realtime Walkthroughs • In an animated environment, trace fixed length paths. • Keeping the last N images of the last N paths, the oldest image is replaced by the new one each time . • Render the global diffuse illumination (only direct illumination) into textures, then can be displayed interactively.

  14. Results

  15. Results

  16. Results

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