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Incident Light FieldThe distribution of light in a static scene with a fixed illumination
Dr. Kurt Debattista Prof. Alan Chalmers
Debmalya Sinha
Courtesy: J. Unger / Linköping University
Synthetic objects on a physical table with real life lighting
Acquisition
Dynamic or StaticLarge Camera Array, Mirror sphere, Plane Mirror, HDR video, SfM (structure from motion)
Physical Scene
Representation
2PPPDP2SPDPP
Rendering
Storage
Virtual Scene
1. Image Based Lighting
2. Light FieldIncident Light Field
My
McA
wesome
light r
ays
We require an Environment Map
A Panoramic image of the environment that envelops the object space we’re about to Render.
1. Image Based Lighting
2. Light FieldIncident Light Field
Courtesy: nVidia
1. Image Based Lighting
2. Light FieldIncident Light Field
We take several pictures from spatially varying points on the camera plane.
Each of the pictures differ a little by angle
Courtesy: Pat Hanrahan / Stanford University
1. Image Based Lighting
2. Light FieldIncident Light Field
1. Image Based Lighting
2. Light FieldIncident Light Field
1. Image Based Lighting
2. Light FieldIncident Light Field
The distribution of light in a static scene with a fixed illumination
We take separate environment map of each little segments of the space to record the incident light rays on the entire object space we are about to render.
Courtesy: J. Unger / Linköping University
Acquisition
Dynamic or StaticLarge Camera Array, Mirror sphere, Plane Mirror, HDR video, SfM (structure from motion)
Physical Scene
Representation
2PPPDP2SPDPP
Rendering
Storage
Virtual Scene
Representation
Represented by 7 dimension Plenoptic function on a point P
θ,φ -> direction of light ray from P, λ -> wavelength of incident light, t -> timeVx,Vy,Vz -> Cartesian coordinate of P.
P = P(θ,φ,λ,t,Vx,Vy,Vz)
Which can be reduced to a 4D function
P = P(θ,φ,u,v)
Assuming, the incident light only comes from the upper hemisphere of the surface [Vx,Vy] ([u,v]).
0 ≤ φ ≤ π/2 and -π ≤ θ ≤ π
Plenoptic parameterization
Acquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene
RepresentationAcquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene
2PP
PDP
2SP
DPP
Line Space parameterization
Two Points on Two Planes
A Point and a Direction
Two Points on a Sphere
A Direction and a Point
2PP
2SP
PDP
DPP
Courtesy: Camahort et al.
Acquisition
Dynamic or StaticLarge Camera Array, Mirror sphere, Plane Mirror, HDR video, SfM (structure from motion)
Physical Scene
Representation
2PPPDP2SPDPP
Rendering
Storage
Virtual Scene
AcquisitionAcquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene Light Probes
A Light Probe is an omni-directional (360° panoramic) high-dynamic range image. (Debevec et al.)
• Typically a highly reflective silvered ball is used.• An HDR Image is taken of the ball.
Problems:• The image has the reflection of the camera itself.• Has to take two images from different direction to get rid
of the reflection of camera.• The edges are stretched badly and needs efficient warping.
AcquisitionAcquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene Light Probes for ILF
Techniques
• Single HDR image of Light probe• HDR video of a moving Light Probe• HDR video from fisheye lens• Light Probe Array• Plain Mirror (edge coded)
Edge coded plain mirror - Courtesy: Ihrke et al. / INRIA Labs
Mirror Sphere array - Courtesy: Dr. J. Unger
HDR video with fisheye lens - Courtesy: Dr. J. Unger
AcquisitionAcquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene Light Probes for ILF
Problems of mirror sphere array
• Reflection from other Mirrors• Camera reflection
Problems of HDR Video setup
• Impractical for big space
AcquisitionProposals
1. Bowls are better than Balls:Concave light probes to eliminate mutual reflection
2. 3D space coverage:45* angle concave probe plane to capture uneven surface such as race tracks
Far fetched idea:probe fitted in a Quadraptor!
Acquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene
Blocked for obvious reasons !
AcquisitionProposals
1. Bowls are better than Balls:Concave light probes to eliminate mutual reflection
2. 3D space coverage:45* angle concave probe plane to capture uneven surface such as race tracks
Far fetched idea:probe fitted in a Quadraptor!
Acquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene
1 2 3 4 5 6 7
Move Direction
Blocked for obvious reasons !
AcquisitionProposals
1. Bowls are better than Balls:Concave light probes to eliminate mutual reflection
2. 3D space coverage:45* angle concave probe plane to capture uneven surface such as race tracks
Far fetched idea:probe with a gimbal fitted in a Quadraptor!
Acquisition
Physical Scene
Representatio
n
Rendering
Storage
Virtual Scene
Little inefficient for covering large space
provides much more mobility than a fixed camera setup
Blocked for obvious reasons !
AcquisitionPhysical Scene
Representation
Rendering
Storage
Virtual Scene
ToDoin the next months
• Re-creating the ILF acquisition with spherical probe.• Implementing it into PARC• Comparing to original results in terms of Rendering
Artifacts• Seam• Hair• Pixelation• Ghosting• Disparity problem
Questions?