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study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
study Active Refocusing Of Images And Videos
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study Active Refocusing Of Images And Videos

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  • 本文介紹一個簡單的方法由 projector 打出去的點光源集作主動探測物體深度的工具復原後的影像 (dots removal)後 點光源探測的深度,合成細緻的 depth map再以此作 image refocusing現階段的 depth map, 已經足夠作 dynamic scenes. [Hoiem et al. 05] – automatically constructing rough scene structure from a single image
  • Projection dots 透過 lens, 在 scene surface 上留影. 而 camera 照的是 mirror 上的結果. same optical axis: 設計上,希望從camera 成像平面上打光出去. 有同樣的 optical axis. camera 上的成像D(dots), 可依光學原理推出 u (object 到 lens 的 depth). 另外有以下的好處Foreshortening(因透視而縮減的高度,長度) asymmetries between the camera & projector viewpoints shadows occlusions
  • Transcript

    • 1. Francesc Moreno-NoguerComputer Vision Lab.EcolePolytechniqueFédérale de LausannePeter N. BelhumeurShree K. NayarColumbia University<br />SIGGRAPH 2007<br />study<br />Active RefocusingofImages and Videos<br />
    • 2. Abstract<br />Use an activeilluminationmethod for depth estimation from a singleimage<br />Near<br />Far<br />Alternate Lighting<br />Refocused (Near)<br />Acquired Image<br />Computed Depth<br />Refocused (Far)<br />
    • 3. Outlines<br />Introduction<br />Related Work<br />Overview<br />Projection Dot Defocus Analysis<br />Dot Removal & Depth Estimation<br />Realistic Refocusing<br />Result<br />Limits and Conclusions<br />
    • 4. Introduction of Refocusing<br />Challenges of Active Refocusing<br />Dynamic scenes  Depth Estimation be done in a single frame <br />Active illumination<br />Full resolution depth map <br />Projection Dot removal<br />Partial Occlusions<br /> captured<br /> blur kernels at depth k<br />In-focus<br />
    • 5. Related work<br />
    • 6. Relative Work: Depth Estimation<br />Passive Methods<br />Active Illumination Methods<br />Shape from shading<br />Cannot handle depth discontinuities<br />Coded Aperture [Levin et al. SIGGRAPH 07]<br />Cam. H.W. modify<br />Require Light Source Pattern<br />Structured Light [Salvi et al. Pattern Recognition ,04]<br />No pattern removal<br />Projector Temporal Defocus [Zhang & Nayar SIGGRAPH06]<br />
    • 7. Relative Work: Digital Refocusing<br />Refocusing Given Depth<br />Light Field Photography<br />Synthesis Images:Ray Tracing [Cook SIGGRAPH84]<br />Require complete 3D model<br />Real Images: Convolution[Photoshop; IrisFilter]<br />Partial Occlusions Problem<br />Light Field Camera[Ng SIGGRAPH05]<br />Cam. H.W. modify<br />Resolution losses<br />Dappled Photography [Veeraraghavan SIGGRAPH07]<br />Cam. H.W. modify<br />Layer<br />
    • 8. Depth Estimation<br />Depth Map Completion using Segmentation<br />Dots Removal<br />Dots Removed<br />Acquired Image<br />Dense Depth<br />Matting<br />Dots Depth Estimationby Calibration<br />Sparse Depth Map<br />Color Segmentation<br />Merged Segmentation<br />
    • 9. Realistic Refocusing<br />Dots Removed<br />Depth Map<br />Focal plane,<br />Apertures,<br />Window size of dots<br />
    • 10. Projection Dot Defocus Analysis<br />
    • 11. System Design<br />Projector<br />Camera & Projector Coaxial  have same Optical Axis<br />
    • 12. Blur Circle Diameter, D<br />fc<br />v<br />w<br />r<br />D<br />u<br />uf<br />with dot size w <br />(in the projector plane)<br />
    • 13. Blur Circle Radiance, I<br />fc<br />v<br />w<br />r<br />D<br />u<br />uf<br />with dot size w <br />(in the projector plane)<br />based on Image Irradiance Equation derived in [Horn 86]<br />
    • 14. Camera images of dot of 3*3 pixels projected onto different depths<br />
    • 15. Camera images of dot of 3*3 pixels projected onto different depths<br />
    • 16. Dot removal and depth estimation<br />
    • 17. Sparse Depth Map<br />…<br />Depth 1<br />Depth 2<br />Calibration Patches<br />Estimated<br />=<br />X<br />
    • 18. Sparse Depth Map<br />…<br />Depth 1<br />Depth 2<br />Calibration Patches<br />Estimated<br />
    • 19. Sparse Depth Map<br />…<br />Depth 1<br />Depth 2<br />Calibration Patches<br />Estimated<br />
    • 20. Depth Estimation - ux<br />Non-textured Surface<br />Textured Surfaces (texture by itself introduces brightness variation) <br />based on Unsupervised Learning Alg. [Figueiredo and Jain IEEE02]<br />
    • 21. Depth map completion using segmentation<br />
    • 22. Depth Map Completion<br />Over-Segmentation<br />Sparse Depth Map<br />Iterative Merging<br />Mean-Shift<br />[Comaniciu & Meer 02]<br />
    • 23. Depth Map Completion – Iterative Merging <br />Loop: Apply Greedy alg. to group segments<br />Merge the two most similar neighboring segments <br />Re-computes the features of the new merged segment <br />Iterative Merging<br />
    • 24. Similarity between Segments<br />Color C Depth D Texture T<br />Sim(i,j)=λC∙dist(Ci,Cj)+λD∙dist(Di,Dj)+λT∙dist(Ti,Tj) <br />
    • 25. Depth Map Completion – Refine the Depth Disc.<br />Matting Algorithm<br />[Wang & Cohen 05]<br />Noisy Depth Map<br />
    • 26. Realistic refocusing<br />
    • 27. Challenge of Refocusing<br />Partial occlusions<br />Different parts of the lens may see different views at an object boundary<br /> Create missing region by detecting discontinuities in depth map and extending the occluded surface using texture synthesis<br />Foreground/background transitions<br />Pixels at depth discontinuities may receive contributions from the fr. and bg.<br />Blend fr./bg. images within the boundary region<br />
    • 28. Realistic Refocusing produces better results than existing approaches<br />Realistic Refocusing<br />Canon + wide aperture<br />Photoshop - blur<br />IrisFilter<br />Original<br />
    • 29. Partial Occlusions<br />
    • 30. Refocusing with Alpha Maps<br />Foreground (F)<br />Boundary (C)<br />Background (B)<br />R<br />R<br />R<br />R<br />CЄF<br />CЄB<br />CЄF<br />CЄB<br />+<br />=<br />R<br />*<br />*<br />
    • 31. Result<br />
    • 32. Limitations<br />Due to Active Illumination<br />Translucent objects exhibit subsurface scattering<br />Blurred dots are too weak to detect<br />Very dark<br />Highly inclined surface (&gt; 70°)<br />Poor in outdoor with strong sunlight<br />ex: the ball and the table are assigned diff. depths due to errors on segmentation errors<br />
    • 33. Limitations<br />Due to sparse dots<br />Sparsity of the depth estimation<br />Errors in the initial segmentation of the image<br />ex: incorrect depth due to segmentation err.<br />
    • 34. Conclusions<br />Contribution<br />Future Work<br />An active illumination depth estimation with single <br />Single Frame, Complete Depth Map, Texture/Textureless scenes<br />Projected Light Patterns are Removed<br />High resolution refocusing of images and videos<br />Incorporate the method into digital cameras<br />Use intra-red source for projecting the dot patter to make the depth estimation more robust in the case of highly textured scenes <br />
    • 35. end<br />

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