Image or Object? Michael F. Cohen Microsoft Research
Is this real? Photo by Patrick Jennings Copyright 1995, 96, 97 Whistler B. C. Canada
A mental model Photo by Patrick Jennings Copyright 1995, 96, 97 Whistler B. C. Canada ?
Sue Vision
Is this real? Michael F. Cohen, Shenchang Eric Chen, John R. Wallace, and Donald P. Greenberg 1988, A Progressive Refinement Approach to Fast Radiosity Image Generation.
Bob Graphics
Computer Graphics Image Output Model Synthetic Camera
Real Scene Computer Vision Real Cameras Model Output
Computer Graphics Meets Computer Vision
Combined Model Real Scene Real Cameras Image Output Synthetic Camera
But, vision technology falls short Model Real Scene Real Cameras Image Output Synthetic Camera
… and so does graphics. Model Real Scene Real Cameras Image Output Synthetic Camera
Image Based Rendering Real Scene Real Cameras -or- Expensive Image Synthesis Images+Model Image Output Synthetic Camera
Ray q Constant radiance time is fixed q 5D 3D position 2D direction
All Rays q Plenoptic Function all possible images too much stuff!
Line q Infinite line q 4D 2D direction 2D position
Ray q Discretize q Distance between 2 rays Which is closer together?
Image q What is an image? q All rays through a point Panorama?
Image q 2D position of rays has been fixed direction remains
Image q Image plane q 2D position
q Image plane q 2D position Image
q Light leaving towards “eye” q 2D just dual of image Object
q All light leaving object
Object q 4D 2D position 2D direction
Object q All images
Object q Computer Vision?
Plenoptic Function q 5D q Rays
Lumigraph / Lightfield q Outside convex space q 4D Stuff Empty
Lumigraph q Inside convex space q 4D Empty Stuff
Lumigraph q How to organize capture render
Lumigraph - Organization q 2D position q 2D direction s
Lumigraph - Organization q 2D position q 2 plane parameterization s u
Lumigraph - Organization q 2D position q 2 plane parameterization u s t s,t u,v v s,t u,v
Lumigraph - Organization Hold s,t constant Let u,v vary q An image s,t u,v
Lumigraph - Organization q Discretization higher res near object if diffuse captures texture lower res away captures directions s,t u,v
Lumigraph - Capture q Idea 1 Move camera carefully over s,t plane Gantry see Lightfield paper s,t u,v
Lumigraph - Capture q Idea 2 Move camera anywhere Rebinning see Lumigraph paper s,t u,v
Lumigraph - Rendering q For each output pixel determine s,t,u,v either find closest discrete RGB interpolate near values s,t u,v
Lumigraph - Rendering q For each output pixel determine s,t,u,v either use closest discrete RGB interpolate near values s u
Lumigraph - Rendering q Nearest closest s closest u draw it q Blend 16 nearest quadrilinear interpolation s u
Lumigraph - Rendering q Depth Correction closest s intersection with “object” best u closest u s u
Lumigraph - Rendering q Depth Correction quadralinear interpolation new “closest” like focus s u
Lumigraph - Rendering q Fast s,t,u,v finding scanline interpolate texture mapping shear warp s u
Lumigraph - Rendering q Fast s,t,u,v finding scanline interpolate texture mapping shear warp s u s1,u1 s2,u2
Lumigraph - Rendering q Fast s,t,u,v finding scanline interpolate texture mapping shear warp s u
Lumigraph - Rendering q Fast s,t,u,v finding scanline interpolate texture mapping shear warp s u
Lumigraph - Demo q Lumigraph Lion, Fruit Bowl, Visible Woman, Path Tracing
Lightfield - Demo q Digital Michelangelo Project Marc Levoy, Stanford University Lightfield (“night”) assembled by Jon Shade
Surface Lightfields q Turn 4D parameterization around q Leverage coherence
Surface Lightfields q Wood et al, SIGGRAPH 2000
3D Representations q Image is 2D q Lumigraph is 4D q What happened to 3D? 3D Lumigraph subset Concentric mosaics
3D Lumigraph q One row of s,t plane i.e., hold t constant s,t u,v
3D Lumigraph q One row of s,t plane i.e., hold t constant thus s,u,v a “row of images” s u,v
Concentric Mosaics q Replace “row” with “circle” of images
Concentric Mosaics
q From above
Concentric Mosaics q From above
Concentric Mosaics q Panorama
2.5D Representations q Image is 2D q Lumigraph is 4D q 3D 3D Lumigraph subset Concentric mosaics q 2.5D Layered Depth Images View Dependent Surfaces
Layered Depth Image Image Depth Layered 2.5 D ?
Layered Depth Image q Rendering from LDI Incremental in LDI X and Y Guaranteed to be in back-to-front order
Layered Depth Image q Rendering from LDI Incremental in LDI X and Y Guaranteed to be in back-to-front order
Layered Depth Image (LDI)
Tiled LDIs q Multiresolution q Directionally dependent
View Dependent Surfaces
Summary q 5D: Plenoptic Function (Ray) q 4D: Lumigraph / Lightfield q 3D: Lumigraph Subset q 3D: Concentric Mosaics q 2.5D: Layered Depth Image q 2.5D: View Dependent Models q 2D: Image
Thanks q Peter-Pike Sloan (Lumigraph) q Jonathan Shade (Lightfield, LDI) q Marc Levoy, Stanford University Michaelangelo data set