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Novel Depth Cues from Uncalibrated Near-field Lighting

This paper explores how uncalibrated near-field lighting can provide depth cues in various scenes, including indoor, night, underwater, and underground environments. By moving an uncalibrated point light source along a line or plane, depth information can be extracted using the inverse-square fall-off principle. The study focuses on the appearance model, BRDF, illumination, viewing angles, foreshortening, and distance to the source. Experimental setups involving LEDs, cameras, and scene intersections are used for analysis. The method is effective for Lambertian scenes, providing depth ordering and symmetry pairs.

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Novel Depth Cues from Uncalibrated Near-field Lighting

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  1. Novel Depth Cues from Uncalibrated Near-field Lighting Sanjeev J. Koppal and Srinivasa Narasimhan Carnegie Mellon University Sponsors: ONR and NSF

  2. Distant Lighting Sun Parallel Rays Scene

  3. Near-field Lighting Indoor Night Underwater Underground

  4. Calibrated Near Point Light Source 1 2 R Scene Inverse-square fall-off can give depth information (Clark 92, Iwahori et al 94, Kao and Fuh 95, Magda et al 01, Zickler et al 02,Prados and Faugeras 05)

  5. Our Key Idea ‘baseline’ Scene Move an uncalibrated point light source in a line or a plane

  6. Appearance Model BRDF Illumination and Viewing angles Foreshortening Distance to Source

  7. Experimental Setup LED Camera Scene

  8. Plane-Scene Intersectionsfor Lambertian Scenes

  9. Light source moves in a line Scene t = 0 t = i Camera t = n

  10. Maxima in Intensity Scene t = 0 t = i Plane perpendicular to light source path. Camera t = n

  11. Lambertian Scenes Lambertian Model: Albedo Solve for maxima location: Quadratic Expression for maxima: Shortest distance to light source path If D is small, maxima happens at t = i

  12. Moving the Light Source in a Line

  13. Moving the Light Source in a Line

  14. Input Images

  15. Plane-Scene Intersections

  16. Similar to Structured Light

  17. Rough Earthen Pot

  18. Painted House

  19. Metal Office Desk

  20. Wax Candle

  21. Depth Orderingfor Homogeneous Scenes

  22. Light source moves in a plane Scene Camera

  23. Integrating the Profile Q Q P P Overlapped Incident Angles Integral of Profile: S < S if: p q Works for convex Lambertian scenes

  24. Moving the Light Source in a Plane

  25. Moving the Light Source in a Plane

  26. Input Images

  27. Depth Ordering

  28. Plotting ordering as a pseudo-depth

  29. Plastic Beach Ball

  30. Plastic Beach Ball

  31. Polyresin Statue

  32. Polyresin Statue

  33. Depth Orderings from Different ‘Views’

  34. Depth Orderings from Left Plane

  35. Depth Orderings from Image Plane

  36. Depth Orderings from Right Plane

  37. Symmetry Pairsfor Homogeneous Scenes

  38. Matching Profiles Scene Camera

  39. Matching Profiles

  40. Light source moves in reflection plane

  41. Light source moves in reflection plane

  42. Input Images

  43. Symmetry Pairs

  44. Metal Office Desk

  45. Conclusions • Line or plane paths for a near light source are a ‘baseline’. • Depth cues can be obtained from such uncalibrated light paths. • The cues are from the light source ‘viewpoint’ and not from the camera.

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