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Differential Instant Radiosity for Mixed Reality

Differential Instant Radiosity for Mixed Reality. Martin Knecht, Christoph Traxler, Oliver Mattausch, Werner Purgathofer, Michael Wimmer Institute of Computer Graphics and Algorithms Vienna University of Technology. Motivation. Motivation. Problem statement.

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Differential Instant Radiosity for Mixed Reality

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  1. Differential Instant Radiosity for Mixed Reality Martin Knecht, Christoph Traxler, Oliver Mattausch, Werner Purgathofer, Michael Wimmer Institute of Computer Graphics and AlgorithmsVienna University of Technology

  2. Motivation Martin Knecht

  3. Motivation Martin Knecht

  4. Problem statement • Virtual objects should seamlessly blend into the real scene • Provide a plausible illusion • Simulation of light interaction between real and virtual objects is necessary • Solution should run at interactive to real-time frame rates Martin Knecht

  5. Related Work • Image Based Lighting • Ritschel and Grosch used a HDR camera to capture environment • Hierarchical Importance Sampling, Clarberg • Real-time Global Illumination • Instant Radiosity introduced by Keller • Imperfect Shadow Maps from Ritschel et. al • Merging Real and Virtual Scenes • Differential Rendering introduced by Fournier and extended by Debevec • Differential Photon Mapping from Grosch Martin Knecht

  6. Assumptions Geometry of real scene known BRDFs of real surfaces are known Surrounding illumination is distant Martin Knecht

  7. Differential Instant Radiosity for MR • Idea: Combine Differential Rendering (DR) with Instant Radiosity (IR) • Why?  DR adds virtual objects to real scene IR fast method to compute GI solution in real-time • But: Two solutions are needed for DR! not really • How? Keep track on the light paths Martin Knecht

  8. GI - Instant Radiosity • Use Virtual Point Lights (VPLs) to approximate global illumination Martin Knecht

  9. GI - Instant Radiosity • Use Virtual Point Lights (VPLs) to approximate global illumination Martin Knecht

  10. GI - Instant Radiosity • Use Virtual Point Lights (VPLs) to approximate global illumination Martin Knecht

  11. GI - Instant Radiosity • Use Virtual Point Lights (VPLs) to approximate global illumination Martin Knecht

  12. GI - Instant Radiosity • Use Virtual Point Lights (VPLs) to approximate global illumination Martin Knecht

  13. Differential Rendering • Method to add virtual objects into real scene images • Compute two global illumination solutions and add only difference to real scene image + Minimizes visual error from wrong BRDF approximations - We need to calculate two GI solutions in real-time Martin Knecht

  14. Differential Rendering GI(Real + Virtual) GI(Real) Difference Buffer Grey means no difference Martin Knecht

  15. Differential Rendering Masked Video Image Difference Buffer Final Image Martin Knecht

  16. Heckberts classification Courtesy of Paul Guerrero • How to get GI(Real+Virtual) and GI(Real)? • Keep track on the light paths • L: Lightsource • D: Diffuse light bounce • S: Specular light bounce • E: Eye Martin Knecht

  17. Heckberts classification Courtesy of Paul Guerrero • How to get GI(Real+Virtual) and GI(Real)? • Keep track on the light paths • L: Lightsource • D: Diffuse light bounce • S: Specular light bounce • E: Eye • Direct illumination: LDE Martin Knecht

  18. Heckberts classification Courtesy of Paul Guerrero • How to get GI(Real+Virtual) and GI(Real)? • Keep track on the light paths • L: Lightsource • D: Diffuse light bounce • S: Specular light bounce • E: Eye • Direct illumination: LDE • 1st bounce diffuse indirect illumination: LDDE Martin Knecht

  19. Differential Instant Radiosity for MR Calculate shading result only once Decide on path information to which GI solution the result belongs L[x]D[x]E L[x]D[x]D[x]E [x] can be „real“ or „virtual“ All „real“ then add to GI(Real+Virtual) and GI(Real) One [x] „virtual“, only add to GI(Real+Virtual) Martin Knecht

  20. Differential Instant Radiosity for MR • LRDRDRE path GI(Real + Virtual) GI(Real) Martin Knecht

  21. Differential Instant Radiosity for MR • LRDRDRE path • Added to both Buffers GI(Real + Virtual) GI(Real) Martin Knecht

  22. Differential Instant Radiosity for MR • LRDRDVE path GI(Real + Virtual) GI(Real) Martin Knecht

  23. Differential Instant Radiosity for MR • LRDRDVE path • Add only to the GI(Real+Virtual) Buffer GI(Real + Virtual) GI(Real) Martin Knecht

  24. Differential Instant Radiosity for MR • Take blocking geometry into account Martin Knecht

  25. Differential Instant Radiosity for MR • LRDRDRE path GI(Real + Virtual) GI(Real) Martin Knecht

  26. Differential Instant Radiosity for MR • LRDRDRE path • Virtual red wall blocks light! GI(Real + Virtual) GI(Real) Martin Knecht

  27. Limitations Martin Knecht

  28. Limitations Double shadowing Incosistent color bleeding Martin Knecht

  29. Results • Test device • Core2 Quad CPU Q9550 at 2.8GHz • 8GB RAM • NVIDIA Geforce GTX 285 with 1GB VRAM • Windows 7 64-Bit • C# with SlimDX to access DirectX 10 Martin Knecht

  30. Results Martin Knecht

  31. Results Martin Knecht

  32. Results Martin Knecht

  33. Results Martin Knecht

  34. Our method uses instant radiosity to simulate mutual influence between objects Direct Illumination Indirect Illumination Combination of Differential Rendering and Instant Radiosity Lightsources, objects, camera can be dynamic Cannot take all paths into account Works reasonable fast (20 – 30 fps) Conclusion Martin Knecht

  35. Consider all light paths Add camera artifacts Camera-based, real-time reconstruction of geometry Real-time BRDF estimation Future Work Martin Knecht

  36. Thank you for your attention! Martin Knecht

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