Novel Depth Cues from Uncalibrated Near-field Lighting Sanjeev J. Koppal and Srinivasa Narasimhan Carnegie Mellon University Sponsors: ONR and NSF.
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Novel Depth Cues from Uncalibrated Near-field Lighting Sanjeev J. Koppal and Srinivasa Narasimhan Carnegie Mellon University Sponsors: ONR and NSF Distant Lighting Sun Parallel Rays Scene Near-field Lighting Indoor Underground Night Underwater Calibrated Near Point Light Source 1 R2 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) Our Key Idea ‘baseline’ Scene Move an uncalibrated point light source in a line or a plane Appearance Model BRDF Illumination and Viewing angles Distance to Source Foreshortening Experimental Setup LED Camera Scene Plane-Scene Intersections for Lambertian Scenes Light source moves in a line Scene t=0 t=i Camera t=n Maxima in Intensity Scene t=0 t=i Plane perpendicular to light source path. Camera t=n Lambertian Scenes Lambertian Model: Solve for maxima location: Expression for maxima: Albedo Quadratic Shortest distance to light source path If D is small, maxima happens at t = i Moving the Light Source in a Line Moving the Light Source in a Line Input Images Plane-Scene Intersections Similar to Structured Light Rough Earthen Pot Painted House Metal Office Desk Wax Candle Depth Ordering for Homogeneous Scenes Light source moves in a plane Scene Camera Integrating the Profile Q Q P Overlapped Incident Angles Integral of Profile: Sp < Sq if: Works for convex Lambertian scenes P Moving the Light Source in a Plane Moving the Light Source in a Plane Input Images Depth Ordering Plotting ordering as a pseudo-depth Plastic Beach Ball Plastic Beach Ball Polyresin Statue Polyresin Statue Depth Orderings from Different ‘Views’ Depth Orderings from Left Plane Depth Orderings from Image Plane Depth Orderings from Right Plane Symmetry Pairs for Homogeneous Scenes Matching Profiles Scene Camera Matching Profiles Light source moves in reflection plane Light source moves in reflection plane Input Images Symmetry Pairs Metal Office Desk 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.