1Image-Based Lighting II15-463: Rendering and Image ProcessingAlexei Efros…with a lot of slides donated by Paul DebevecReach for the sky• How can we capture the whole sky as an environment map?• What happens with the sun?2Direct HDR Capture of the Sun and SkyDirect HDR Capture of the Sun and Sky• Use Sigma 8mm fisheye lens and Canon EOS 1Ds to cover entire sky• Use 3.0 ND filter on lens back to cover full range of light– Only 0.1% of light gets through!• Use Sigma 8mm fisheye lens and Canon EOS 1Ds to cover entire sky• Use 3.0 ND filter on lens back to cover full range of light– Only 0.1% of light gets through!Stumpfel, Jones, Wenger, Tchou, Hawkins, and Debevec. “Direct HDR Capture of the Sun and Sky”. To appear in Afrigraph 2004.Stumpfel, Jones, Wenger, Tchou, Hawkins, and Debevec. “Direct HDR Capture of the Sun and Sky”. To appear in Afrigraph 2004.Extreme HDR Image SeriesExtreme HDR Image Series1 secf/41 secf/41/4 secf/41/4 secf/41/30 secf/41/30 secf/41/8000 sec f/161/8000 sec f/161/30 secf/161/30 secf/161/250 secf/161/250 secf/161/1000 secf/161/1000 secf/1631 secf/41 secf/41/4 secf/41/4 secf/41/30 secf/41/30 secf/41/8000 sec f/16only image that does not saturate!1/8000 sec f/16only image that does not saturate!1/30 secf/161/30 secf/161/250 secf/161/250 secf/161/1000 secf/161/1000 secf/16Extreme HDR Image Series- sun closeupExtreme HDR Image Series- sun closeupSpectral Calibration – ND filters are NOT Necessarily Neutral!Spectral Calibration – ND filters are NOT Necessarily Neutral!Before correctionBefore correctionAfter correction based on MacBeth ColorChecker chart appearanceAfter correction based on MacBeth ColorChecker chart appearance4Two Complete days of HDR LightingTwo Complete days of HDR LightingFeb 22, 2004 Feb 23, 2004(day averages at 1 min. intervals)524 Samples per Pixel – 6h, 22min624 Samples per Pixel – 6h, 22minHDRI Sky Probe7Clipped Sky + Sun SourceLit by sky only8Lit by sun onlyLit by sun and sky9Illuminating a Small SceneIlluminating a Small Scene10We can now illuminatesynthetic objects with real light.How do we add synthetic objects to a real scene?We can now illuminatesynthetic objects with real light.How do we add synthetic objects to a real scene?Real Scene ExampleReal Scene ExampleGoal: place synthetic objects on tableGoal: place synthetic objects on table11Light Probe / Calibration GridLight Probe / Calibration Gridreal scenereal sceneModeling the SceneModeling the Scenelight-based modellight-based model12The Light-Based Room ModelThe Light-Based Room Modelreal scenereal sceneModeling the SceneModeling the Scenesynthetic objectssynthetic objectslight-based modellight-based modellocal scenelocal scene13The Lighting ComputationThe Lighting Computationsynthetic objects(known BRDF)synthetic objects(known BRDF)distant scene (light-based, unknown BRDF)distant scene (light-based, unknown BRDF)local scene(estimated BRDF)local scene(estimated BRDF)Rendering into the SceneRendering into the SceneBackground PlateBackground Plate14Rendering into the SceneRendering into the SceneObjects and Local Scene matched to SceneObjects and Local Scene matched to SceneDifferential RenderingDifferential RenderingLocal scene w/o objects, illuminated by modelLocal scene w/o objects, illuminated by model15Differential Rendering (2)Difference in local sceneDifferential Rendering (2)Difference in local scene--==Differential RenderingDifferential RenderingFinal ResultFinal Result16IMAGE-BASED LIGHTING INFIATLUXPaul Debevec, Tim Hawkins, Westley Sarokin, H. P. Duiker, Christine Cheng, Tal Garfinkel, Jenny HuangSIGGRAPH 99 Electronic Theater17HDR Image SeriesHDR Image Series2 sec2 sec1/4 sec1/4 sec1/30 sec1/30 sec1/250 sec1/250 sec1/2000 sec1/2000 sec1/8000 sec1/8000 sec18Stp1 PanoramaStp1 PanoramaAssembled PanoramaAssembled Panorama19Light Probe ImagesLight Probe ImagesCapturing a Spatially-Varying Lighting EnvironmentCapturing a Spatially-Varying Lighting Environment20Identified Light SourcesIdentified Light SourcesThe MovieThe Movie21Simulating the Glare in the Human EyeSimulating the Glare in the Human Eye• Greg Spencer, Peter Shirley, Kurt Zimmerman, and Donald Greenberg. Physically-based glare effects for digital images. SIGGRAPH 95.• Greg Spencer, Peter Shirley, Kurt Zimmerman, and Donald Greenberg. Physically-based glare effects for digital images. SIGGRAPH 95.Scattering in the eyeWhat’s the scattering model?22HDR ImageGaussian Blur, LDR information Only23Gaussian Blur, Full HDR InformationFull HDR Disc Blur24Frame Postprocessingin Rendering with Frame Postprocessingin Rendering with Compositing Complex Objects25Rendering Light Probes as Light SourcesRendering Light Probes as Light Sources1999199926A Lighting Reproduction ApproachA Lighting Reproduction ApproachComposited ResultsComposited Results27Environment Map from Single Image?Environment Map from Single Image?Eye as Light Probe! (Nayar et al)Eye as Light Probe! (Nayar et al)28Cornea is an ellipsoidCornea is an ellipsoidEllipsoid fittingEllipsoid
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