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Image Based Image Based Rendering Rendering
Image Based Image Based Rendering Rendering
Light Field• Gershun in 1936
– An illuminated objects fills the surrounding space with light reflected of its surface, establishing the object’s “light field”
• Adelson and Bergen 1991– Plenoptic Function
Plenoptic Funtions• An observer at any point in space (x,y,z) and any m
oment in time (t) can look in any direction(θ,ǿ.) and record the incoming light intensity Φ at all visible wavelength λ
• Φ= Φ(x,y,z,t, θ,ǿ., λ)
• Φ is the radiation’s spectral intensity, a scalar value denotes the incoming light’s power per unit per area per solid angle per unit wavelength interval
Image Based Rendering
• If Φis known, any view of the scene can be reconstructed
• IBR an approach to computer-generated 2D-views of natural 3D-scenes
• Approximation of the plenoptic functions from a number of conventional images
IBR Topics• View-Dependent Texture Mapping• Hybrid Geometry and Image Based Rendering• Delta Tree Representation• Multiple-Centre-of-Projection Images• Layered Depth Images• Sprites with Depth• Plenoptic Modeling and Environment Maps• Light Field Rendering and Lumigraphs
Light Field Rendering• M. Levoy• A ray is parameterized
by its intersection coordinates (u,v,s,t)
• The set of all rays that can be parameterized by two grid planes represents a light field slab
Light Field Rendering
Sampling Requirements
• S X T = • 256 x 256• U X V = • 121000 images
IBR with Controllable Illumination
• For a static scene, 3 or more images with “orthogonal” lighting can be used to render all possible lighting conditions
Set of all possible images
• Original 6 Photos with different lighting conditions
• Three basis images
Set of all possible images
• a
IBR and Video Scene with Camera Motion
• A video scene with camera motion contains a sequence of images of different viewing positions
• Applying IBR or IBM, develop algorithm to do video object segmentation
• Object elimination inside a video sequence, like the one in “Rising Sun” - Sean Connery
• Any help to video understanding ?• Evolution of Vision ?