Demonstrating Anisotropic Surface Reflectance with Illustration Based Microfacet Combination.


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Surface Reflectance. glossy silk metal wood. Anisotropic Surface Reflectance. anisotropic. isotropic. Our Goal. demonstrating spatially-shifting anisotropic reflectance. Surface Reflectance in CG. 4D BRDF ?(o,i)Bidirectional Reflectance Distribution Functionhow much light reflected wrt in/out bearings.
Transcripts
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Demonstrating Anisotropic Surface Reflectance with Example-Based Microfacet Synthesis Jiaping Wang 1 , Shuang Zhao 2 , Xin Tong 1 John Snyder 3 , Baining Guo 1 Microsoft Research Asia 1 Shanghai Jiao Tong University 2 Microsoft Research 3

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Surface Reflectance glossy silk metal wood

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Anisotropic Surface Reflectance isotropic anisotropic

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Our Goal displaying spatially-differing anisotropic reflectan ce

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Surface Reflectance in CG 4D BRDF ρ ( o , i ) B idirectional R eflectance D istribution F unction what amount of light reflected wrt in/out bearings o i

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Surface Reflectance in CG 4D BRDF ρ ( o , i ) B idirectional R eflectance D istribution F unction what amount of light reflected wrt in/out headings 6D Spatially-Varying BRDF: SVBRDF ρ ( x , o , i ) BRDF at every surface point x

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Related Work I parametric BRDF models minimized representation simple procurement and fitting need reasonable subtle elements ground truth parametric model [Ward 92]

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Related Work II arranged SVBRDF sensible substantial information set hard to catch long process costly equipment picture enlistment light vault [Gu et al 06]

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Related Work II organized SVBRDF practical expansive information set hard to catch protracted procedure costly equipment picture enrollment light arch [Gu et al 06]

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Microfacet BRDF Model surface displayed by little reflect features [Cook & Torrance 82]

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Microfacet BRDF Model surface demonstrated by modest mirror aspects [Cook & Torrance 82] fresnel term typical dissemination shadow term

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Microfacet BRDF Model in light of Normal Distribution Function (NDF) NDF D is 2D capacity of the midway vector h rules surface appearance

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Challenge: Partial Domains tests from a solitary review course i cover just a sub-district h  Ω of NDF How to acquire the full NDF? ? fractional NDF complete NDF incomplete district

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Solution: Exploit Spatial Redundancy discover surface focuses with comparative yet contrastingly turned NDFs material specimen halfway NDF at every surface point

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Example-Based Microfacet Synthesis incomplete NDFs from other surface focuses Align + = fractional NDF to finish pivoted incomplete NDFs finished NDF

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Comparison ground truth our model isotropic Ward model anisotropic Ward model

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Overall Pipeline BRDF Slice Capture Partial NDF Recovery Microfacet Synthesis

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Overall Pipeline BRDF Slice Capture Partial NDF Recovery Microfacet Synthesis

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Device Setup Camera-LED framework, in light of [Gardner et al 03]

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Capturing Process

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Overall Pipeline BRDF Slice Capture Partial NDF Recovery Microfacet Synthesis

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NDF Recovery modify the microfacet BRDF model Measured BRDF Unknown NDF Shadow Term  , [Ashikhmin et al 00]

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NDF Recovery (con\'t) iterative methodology [ Ngan et al 05 ] settle for NDF, then shadow term works for complete 4D BRDF information [ Ngan et al 05 ] 1.  , [Ashikhmin et al 00] 2.

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Partial NDF Recovery one-sided result on deficient BRDF information [Ngan et al. 05] ground truth NDF shadow term shadow term NDF

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Partial NDF Recovery (con\'t) minimize the predisposition isotropically compel shadow term in every emphasis after requirement before limitation

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Recovered Partial NDF [Ngan et al. 05] ground truth our outcome

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Overall Pipeline Capture BRDF cut Partial NDF Recovery Microfacet Synthesis

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Microfacet Synthesis fractional NDF to finish finished NDF Merged incomplete NDFs

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Microfacet Synthesis (con\'t) clear usage: For N NDFs at every surface point Match against ( N - 1) NDFs at different focuses In M pivot plots for arrangement number of revolutions/examinations: N 2 *M ≈ 5 × 10 11 ( N ≈ 640k , M ≈ 1k )

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Synthesis Acceleration a direct execution: For N NDFs in every surface point Match with ( N - 1) NDFs in other area In M turn plots for arrangement times of circular capacity turn and correlation N 2 * M ≈ 5 × 10 11 ( N ≈ 640k ) Clustering [Matusik et al 03] complete delegate NDFs just (1% of full set) N\' 2 * M ≈ 5 × 10 7 ( N\' ≈ 6.4k )

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Synthesis Acceleration a direct execution: For N NDFs in every surface point Match with ( N - 1) NDFs in other area In M revolution plots for arrangement times of round capacity pivot and correlation N 2 * M ≈ 5 × 10 11 ( N ≈ 640k ) Clustering [Matusik et al 03] complete agent NDFs just (1% of full set) Search Pruning precompute every pivoted competitor prune by means of various leveled seeking N\' 2 * M ≈ 5 × 10 7 ( N\' ≈ 6.4k ) N\'* log( N\'* M ) ≈ 5 × 10 5

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Performance Summary 5-10 hours for BRDF cut procurement in HDR 1 Hour for obtaining in LDR 2-4 hours for picture preparing 2-3 hours for halfway NDF recuperation 2-4 hours for a ccelerated microfacet combination On a PC with Intel Core TM 2 Quad 2.13GHz CPU and 4GB memory

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Model Validation full SVBRDF dataset [Lawrence et al. 06] information from one perspective for demonstrating information from different perspectives for acceptance

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Validation Result

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Limitations visual displaying, not physical precision single-skip microfacet model retro-reflection not took care of spatial repetition of turned NDFs simple fix by pivoting the specimen

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Rendering Result: Satin

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Rendering Result: Wood

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Rendering Result: Brushed Metal

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Conclusions model surface reflectance by means of microfacet amalgamation general and smaller representation high determination (spatial & rakish), sensible result less demanding procurement: single-perspective catch shoddy gadget shorter catching time

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Future Work execution streamlining catching and information handling expansion to non-level articles augmentation to various light ricochet

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Acknowledgments Le Ma for hardware of the LED exhibit Qiang Dai for catching gadget setup Steve Lin, Dong Xu for profitable talks Paul Debevec for HDR symbolism Anonymous analysts for their accommodating recommendations and remarks

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Thank you!

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