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Dual Representations for Light Field Compression. EE368C Project January 30, 2001 Peter Chou Prashant Ramanathan. Outline. Background Model-based Coding Surface Light Fields Trade-offs Duality Proposed Experiments. Light Fields and Compression. What are light fields?
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Dual Representations for Light Field Compression EE368C Project January 30, 2001 Peter Chou Prashant Ramanathan
Outline • Background • Model-based Coding • Surface Light Fields • Trade-offs • Duality • Proposed Experiments
Light Fields and Compression • What are light fields? • 2-D array of images • Why is compression necessary? • Light fields are very large data sets Mouse Hemispherical Light Field University of Erlangen Michelangelo’s Night 96 GB raw image data Stanford Computer Graphics Laboratory
Light Fields with Geometry • Geometry used for light fields to aid compression • ex. model-based coding • Light fields are used with geometry for more realistic rendering • ex. surface light fields
Model-based Coding • Model-based Coding of Multi-Viewpoint Imagery (Magnor and Girod, VCIP-2000) • Eigen-Texture Method: Appearance Compression based on 3D Model (Nishino, Sato, and Ikeuchi, CVPR-1999) http://www.lnt.de/~magnor
Surface Light Fields • Surface Light Fields for 3D Photography (Wood et al., Siggraph 2000) http://grail.cs.washington.edu/projects/slf/
Surface Light Fields (cont’d) • Geometry acquired through range scan • For each point on surface, a lumisphere represents radiance in all directions • Lumispheres are coded using either: • function quantization (similar to VQ) • principal function analysis (similar to PCA)
Trade-offs • Textures + coherency along 4D coordinate directions – warping introduces artifacts, and possible loss of information • Surface Light Fields + more intuitive representation for compression – lumispheres are represented as continuous functions
Duality • View-dominant organization (textures) • Geometry-dominant organization (surface light fields) Surface Points View 1 View 2 View N Views Surface Point 1 Surface Point 2 Surface Point N
Proposed Experiments I • Compare the two organizations for any difference in compression results Surface Points View 1 View 2 View N Views Surface Point 1 Surface Point 2 Surface Point N
Proposed Experiments II • Reparameterize geometry-dominant organization using local coordinate system w.r.t. surface normals Views Surface Point 1 Surface Point 2 Normal Direction View Surface Point N
Proposed Experiments III • Use image data directly, instead of converting from warped texture data Views Surface Point 1 Surface Point 2 image pixels Surface Point N