Incident light field 1
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The document discusses incident light fields, which represent the distribution of light in a static scene with fixed illumination. An incident light field can be represented by capturing separate environment maps of small scene segments to record incident light rays across the entire object space. These light probes are typically captured using high dynamic range images of reflective spheres or mirrors arranged in an array to sample the scene. Open challenges include reducing mutual reflections between probes and enabling coverage of uneven surfaces.
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Incident light field 1
- 1. Incident Light Field The distribution of light in a static scene with a fixed illumination Dr. Kurt Debattista Prof. Alan Chalmers Debmalya Sinha
- 2. Courtesy: J. Unger / Linköping University Synthetic objects on a physical table with real life lighting
- 3. Acquisition Dynamic or Static Large Camera Array, Mirror sphere, Plane Mirror, HDR video, SfM (structure from motion) Physical Scene Representation 2PP PDP 2SP DPP Rendering Storage Virtual Scene
- 4. 1. Image Based Lighting 2. Light Field Incident Light Field We require an Environment Map A Panoramic image of the environment that envelops the object space we’re about to Render.
- 5. 1. Image Based Lighting 2. Light Field Incident Light Field Courtesy: nVidia
- 6. 1. Image Based Lighting 2. Light Field Incident Light Field We take several pictures from spatially varying points on the camera plane. Each of the pictures differ a little by angle Courtesy: Pat Hanrahan / Stanford University
- 7. 1. Image Based Lighting 2. Light Field Incident Light Field
- 8. 1. Image Based Lighting 2. Light Field Incident Light Field
- 9. 1. Image Based Lighting 2. Light Field Incident Light Field The distribution of light in a static scene with a fixed illumination We take separate environment map of each little segments of the space to record the incident light rays on the entire object space we are about to render.
- 10. Courtesy: J. Unger / Linköping University
- 11. Acquisition Dynamic or Static Large Camera Array, Mirror sphere, Plane Mirror, HDR video, SfM (structure from motion) Physical Scene Representation 2PP PDP 2SP DPP Rendering Storage Virtual Scene
- 12. Representation Represented by 7 dimension Plenoptic function on a point P θ,φ -> direction of light ray from P, λ -> wavelength of incident light, t -> time Vx,Vy,Vz -> Cartesian coordinate of P. P = P(θ,φ,λ,t,Vx,Vy,Vz) Which can be reduced to a 4D function P = P(θ,φ,u,v) Assuming, the incident light only comes from the upper hemisphere of the surface [Vx,Vy] ([u,v]). 0 ≤ φ ≤ π/2 and -π ≤ θ ≤ π Plenoptic parameterization Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene
- 13. Representation Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene 2PP PDP 2SP DPP Line Space parameterization Two Points on Two Planes A Point and a Direction Two Points on a Sphere A Direction and a Point 2PP 2SP PDP DPP Courtesy: Camahort et al.
- 14. Acquisition Dynamic or Static Large Camera Array, Mirror sphere, Plane Mirror, HDR video, SfM (structure from motion) Physical Scene Representation 2PP PDP 2SP DPP Rendering Storage Virtual Scene
- 15. Acquisition Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene Light Probes A Light Probe is an omni-directional (360° panoramic) high-dynamic range image. (Debevec et al.) • Typically a highly reflective silvered ball is used. • An HDR Image is taken of the ball. Problems: • The image has the reflection of the camera itself. • Has to take two images from different direction to get rid of the reflection of camera. • The edges are stretched badly and needs efficient warping.
- 16. Acquisition Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene Light Probes for ILF Techniques • Single HDR image of Light probe • HDR video of a moving Light Probe • HDR video from fisheye lens • Light Probe Array • Plain Mirror (edge coded) Edge coded plain mirror - Courtesy: Ihrke et al. / INRIA Labs Mirror Sphere array - Courtesy: Dr. J. Unger HDR video with fisheye lens - Courtesy: Dr. J. Unger
- 17. Acquisition Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene Light Probes for ILF Problems of mirror sphere array • Reflection from other Mirrors • Camera reflection Problems of HDR Video setup • Impractical for big space
- 18. AcquisitionProposals 1. Bowls are better than Balls: Concave light probes to eliminate mutual reflection 2. 3D space coverage: 45* angle concave probe plane to capture uneven surface such as race tracks Far fetched idea: probe fitted in a Quadraptor! Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene Blocked for obvious reasons !
- 19. AcquisitionProposals 1. Bowls are better than Balls: Concave light probes to eliminate mutual reflection 2. 3D space coverage: 45* angle concave probe plane to capture uneven surface such as race tracks Far fetched idea: probe fitted in a Quadraptor! Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene 1 2 3 4 5 6 7 Move Direction Blocked for obvious reasons !
- 20. AcquisitionProposals 1. Bowls are better than Balls: Concave light probes to eliminate mutual reflection 2. 3D space coverage: 45* angle concave probe plane to capture uneven surface such as race tracks Far fetched idea: probe with a gimbal fitted in a Quadraptor! Acq uisit ion Physical Scene Repres entatio n Renderin g Stora ge Virtual Scene Little inefficient for covering large space provides much more mobility than a fixed camera setup Blocked for obvious reasons !
- 21. Acquisition Physical Scene Representation Rendering Storage Virtual Scene ToDoin the next months • Re-creating the ILF acquisition with spherical probe. • Implementing it into PARC • Comparing to original results in terms of Rendering Artifacts • Seam • Hair • Pixelation • Ghosting • Disparity problem
- 22. Questions?