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Michaël Roy. Multiresolution Analysis of Irregular Meshes with Multiple Attributes. 3D Models. High quality 3D models High density meshes High resolution textures Available ressources are always constrained CPU, space, graphics speed, network bandwidth
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Michaël Roy Multiresolution Analysis of Irregular Meshes withMultiple Attributes
3D Models High quality 3D models High density meshes High resolution textures Available ressources are always constrained CPU, space, graphics speed, network bandwidth We need an efficient mesh representation
Motivations (1) Level of Detail Representation Adaptive representation Varies with context Picture of the original object Level 0 117,564 faces (initial scan) Level 5 25,100 faces Level 10 5,232 faces Level 15 1,066 faces Level 20 212 faces
Motivations (2) Multiresolution Analysis Space / Frequency analysis of 3D models Filtering Small scale detail: high frequency Large scale detail: low frequency min max
Wavelet Transform (1) V0 V1 W1 V2 W2 V3 W3 Vi Wi Synthesis(Reconstruction) Analysis(Decomposition) Approximation Details
Wavelet Transform (2) Decomposition A0 A1 Aj-1 V0 V1 V2 Vj-1 Vj B0 B1 Bj-1 W1 Wj W2 Reconstruction Pj Pj-1 P1 Vj-1 Vj-2 V0 Vj V1 Qj Qj-1 Q1 Wj W1 Wj-1
Previous Work (1) Coarse-to-fine hierarchies Lounsbery 1995Multiresolution for surface of arbitrary topological type Zorin 1997Interactive Multiresolution Mesh Editing
Previous Work (2) Fine-to-coarse hierarchies Bonneau 1998Multiresolution Analysis on Irregular Meshes Guskov 1999Multiresolution Signal Processing for Meshes
Multiresolution Analysis Framework Level of detail representation Detail extraction 3D model with attributes Multiresolution Analysis Multiresolution model Intelligent visualization Filtering Denoising Characterisation
Level of detail representation Simplification Level 0 117,564 faces Level 5 25,100 faces Level 10 5,232 faces Level 15 1,066 faces Level 20 212 faces Subdivision
Progressive Mesh (Hoppe 1996) Edge contraction Vertex split econ1 econj-2 econj-1 econ0 ... Mj-1 M0 M1 Mj vsplit1 vsplitj-2 vsplitj-1 vsplit0
Progressive Mesh (Hoppe 1996) Pro: Nested mesh hierarchy Vj Vj-1 ... V1 V0 Edge contraction Vertex split
Progressive Mesh (Hoppe 1996) Con: only one vertex removed per level Edge contraction Vertex split
Global Downsampling Create distinct levels of detail Select an independent set of vertices and remove them by a serie of edge contractions Fine mesh Select vertices to remove Coarse mesh
Detail Computation Details are the difference between a fine mesh and a smoothed version of that mesh Original Smoothed Difference
Surface Relaxation Smooth the surface using a relaxation operator minimizing the curvature
Attribute Details What about the attributes ? Attribute details are the difference between the attributes of a fine mesh and the smoothed attributes of that mesh Original Smoothed Difference
Surface Attribute Relaxation Smooth the attributes using a relaxation operator minimizing the curvature Assume the attributes are linked to the surface
Multiresolution Mesh Decomposition Fine model with attributes Vertex Selection Attribute Surface Relaxation Simplification _ + Coarse model Details
Multiresolution Mesh Reconstruction Coarse model Details Subdivision Attribute Surface Relaxation + + Fine model
Applications Level of detail representation Detail extraction 3D model with attributes Multiresolution Analysis Multiresolution model Characterisation Intelligent visualization Filtering Denoising
Denoising (1) We extend the concept of soft thresholding (AKA wavelet shrinkage) to 3D multiresolution model
Denoising (2) Initial model Laplacian smoothing Soft thresholding
Characterization (1) Thresholding the detail allows highlight of important features of a model
Characterization (2) Impulse Noise Detection Impulse noise Geometric analysis Normal analysis Noise detection Impulse Noise Detection
Intelligent Visualization (1) Level Vs Threshold Reconstruction Threshold reconstruction selects vertices according to their details
Intelligent Visualization (2) 131 242 faces (6.8 MB) 36 772 faces (1.9 MB)
Intelligent Visualization (3) Initial model (73.000 faces) Level reconstruction (17.000 faces) Threshold reconstruction (16.000 faces)
Conclusion Multiresolution decomposition for irregular meshes with attributes Global downsampling Attribute surface relaxation Applications Filtering Denoising using soft thresholding Characterization / feature detection Adaptive reconstruction
Future Work Improve characterization Use the angle between the normal and the detail vector Visualization of meshes with multiple attributes Management of multiple attributes Investigation for better detail metrics e.g. HSI space for colors
Multiresolution Mesh Analysis Thank you for your attention ! Questions ?