Novel Depth Cues from Uncalibrated Near-field Lighting
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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
description
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. Night. Underwater. Underground. - PowerPoint PPT Presentation
Transcript of Novel Depth Cues from Uncalibrated Near-field Lighting
Novel Depth Cues from Uncalibrated Near-field Lighting
Sanjeev J. Koppal and Srinivasa Narasimhan
Carnegie Mellon University
Sponsors: ONR and NSF
Distant Lighting
Sun
Scene
Parallel Rays
Near-field Lighting
Indoor Night
Underground Underwater
Scene
Calibrated Near Point Light Source
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)
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R 2
Our Key Idea
Scene
Move an uncalibrated point light source in a line or a plane
‘baseline’
Appearance Model
BRDF Illumination and Viewing angles Foreshortening
Distance to Source
Experimental Setup
LED
Scene
Camera
Plane-Scene Intersectionsfor Lambertian Scenes
Light source moves in a line
t = i
Scene
Camera
t = 0
t = n
Maxima in Intensity
Scene
Camera
Plane perpendicular to light source path.
t = i
t = 0
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 Orderingfor Homogeneous Scenes
Light source moves in a plane
Scene
Camera
Integrating the Profile
Integral of Profile:
P
Q
Overlapped Incident Angles
P
Q
S < S if:
Works for convex Lambertian scenes
p q
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 Pairsfor 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.
