Novel Depth Cues from Uncalibrated Nearfield Lighting Sanjeev
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 R 2 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.
- Slides: 45