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Relighting with 4D Incident Light FieldsRelighting with 4D Incident Light Fields
Vincent MasselusVincent MasselusPieter PeersPieter PeersPhilip DutréPhilip DutréYves D. WillemsYves D. Willems
Relighting: apply incident illumination to a real object Relighting: apply incident illumination to a real object
Reflectance fieldReflectance field
• Transfer of light through the sceneTransfer of light through the scene
4D exitant
4D incident
Previous workPrevious work
• Debevec et al. SIGGRAPH2000Debevec et al. SIGGRAPH2000
2D exitant2D incident
Images ACM SIGGRAPH
(Environment map)
(Image)
Previous workPrevious work
• Matusik et al. SIGGRAPH2002Matusik et al. SIGGRAPH2002
4D exitant
Images ACM SIGGRAPH
2D incident(Environment map)
(Light field)
Incident IlluminationIncident Illumination
• Usually represented by an environment mapUsually represented by an environment map
2D incident
Spatial varying incident illuminationSpatial varying incident illumination
• Environment Map: incident illumination at one pointEnvironment Map: incident illumination at one point
• New effects:New effects:– Spot light Spot light – ShadowsShadows– ……
• New effects:New effects:– Spot light Spot light – ShadowsShadows– ……
Goal: relighting with angular andspatially varying illuminationGoal: relighting with angular andspatially varying illumination
• One view pointOne view point• Use artificial incident light fields or captured Use artificial incident light fields or captured
from real environment from real environment
Goal: relighting with angular andspatially varying illuminationGoal: relighting with angular andspatially varying illumination
2D exitant(Image)
4D incident(Light Field)
Acquire the reflectance fieldAcquire the reflectance field
• Use camera to capture exitant light fieldUse camera to capture exitant light field• Use projector to create incident light fieldUse projector to create incident light field
Projector
Camera
2D exitant(Image)
4D incident(Light Field)
Data acquisitionData acquisition
Data acquisitionData acquisition
Data acquisitionData acquisition
Data acquisitionData acquisition
Data acquisitionData acquisition
Data Acquisition: setupData Acquisition: setup
ProjectorCamera
Object
Data Acquisition: setupData Acquisition: setup
RelightingRelighting
Incident Light Field
Scene
x W1
W1
Apply
RelightingRelighting
Incident Light Field
Scene
x W1
x W2
W2
RelightingRelighting
Incident Light Field
Scene
x W1
x W2
x W3
W3
RelightingRelighting
Incident Light Field
Scene
x W1
x W2
x W3
…
x WnWn
RelightingRelightingx W1
x W2
x W3
…
x Wn
+
+
+
NxN light bundles NxN light bundles
• #images per projector position = N#images per projector position = N22
• Reduce #images per projector position: O(N)Reduce #images per projector position: O(N)
Speedup Speedup
…
…
…
…
…
N
N
O(N) PatternsO(N) Patterns
Reconstruct basis imageReconstruct basis image
Reconstruct basis imageReconstruct basis image
• Take the minimum value per pixelTake the minimum value per pixel
• #Patterns per projector position = O(N)#Patterns per projector position = O(N)
• Assumption: limited local influence Assumption: limited local influence • Total complexity:Total complexity:
O(PxNO(PxN22) to O(PxN) with P = #projector positions) to O(PxN) with P = #projector positions
Speedup Speedup
… …
4
N
ResultsResults
• 32x7 projector positions32x7 projector positions• 16x16 light bundles16x16 light bundles
• 57344 basis images57344 basis images
reconstructed fromreconstructed from
14336 photographs14336 photographs
Relighting with a captured 4D Incident Light FieldRelighting with a captured 4D Incident Light Field
• Unger Unger et al.et al. EGSR2003 EGSR2003
4D Incident light field vs. 2D Environment map4D Incident light field vs. 2D Environment map
4D 2D
Comparison 4D vs. 2D IlluminationComparison 4D vs. 2D Illumination
2D4D
ResultsResults
• 32x7 projector positions32x7 projector positions• 32x32 light bundles32x32 light bundles
• 229376 basis images229376 basis images
reconstructed fromreconstructed from
28672 photographs28672 photographs
ResultsResults
ResultsResults
Conclusion Conclusion • Acquire reflectance field to relight with 4D Acquire reflectance field to relight with 4D
incident light fieldsincident light fields• Speedup: O(PxNSpeedup: O(PxN22) to O(PxN)) to O(PxN)
• Use other illumination basis functionsUse other illumination basis functions– Gaussians, Wavelets,…Gaussians, Wavelets,…
• Smarter acquisitionSmarter acquisition– What images do we really need?What images do we really need?
• Move the cameraMove the camera– Capture the complete 8D reflection fieldCapture the complete 8D reflection field
Future workFuture work
AcknowledgementsAcknowledgements
• Graphics group from K.U.LeuvenGraphics group from K.U.Leuven• All reviewersAll reviewers• Captured ILF by Jonas Unger Captured ILF by Jonas Unger