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Course Schedule
Structured Lighting
Projector Calibration / Structured Light Reconstruction
Combining Point Clouds Recovered from Multiple Views
Surface Reconstruction from Point Clouds
Elementary Mesh Processing
Related Projects
Conclusion / Q & A
Elementary Mesh Processing
•  We will talk about a few simple algorithms which can be
applied interactively
•  Polygon mesh smoothing / denoising
•  Polygon mesh simplification
•  j3DPGP (Java 3D Photography and Geometry Processing)
Polygon Mesh Smoothing / Denoising
Laplacian Smoothing
N=10
N=40
N=240
Low Pass Filter
•  Laplacian smoothing is the simplest smoothing/denoising algorithm
•  Fix to shrinkage problem: toggle parameter sign at each iteration !
G. Taubin. A Signal Processing Approach To Fair Surface Design.
Siggraph, 1995
Poligon Mesh Simplification / Decimation
•  Algorithms to reduce the number of vertices and faces while
preserving geometric approximation to original shape
•  Vertex clustering (Rossignac & Borrel, 1993)
•  Edge Collapse (Garand Heckbert 1997; many others)
Vertex Clustering
•  Quantize coordinates with respect to a bounding box
•  Identify vertices with same coordinates
•  Remove empty triangles
Vertex Clustering Algorithm
•
•
•
•
•
•
Quantize coordinates with respect to bounding box
Assign a new vertex index to each occupied cell
Determine coordinates of new vertices
Construct new vertex index look-up table
Replace vertex indices in faces
Remove empty triangles from list of faces
Vertex Clustering
•  Advantages
–  Simple to implement
–  Works on large scenes with multiple objects
•  No manifold restriction
•  Disadvantages
–  Produces non-manifold meshes
–  Quality of simplified model is often not very good
Edge Collapse
•
•
•
•
•
Identify endpoints
Determine vertex position
Remove incident triangles
Which edges to collapse ?
In which order ?
Non-existing edges
Basic Edge Collapse Algorithm
•  Put all collapsible edges in a priority queue according to
removal error
•  While queue is not empty
–  Delete minimum edge from queue
–  Collapse edge
–  Identify vertices
–  Remove all incident edges from the queue, determine if
collapsible, recompute removal error, re-insert in queue
•  Need dynamic data structures
Course Schedule
Session II
Structured Lighting
Projector Calibration / Structured Light Reconstruction
Combining Point Clouds Recovered from Multiple Views
Surface Reconstruction from Point Clouds
Elementary Mesh Processing
Related Projects
Conclusion / Q&A
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Course Schedule
Session II
Structured Lighting
Projector Calibration / Structured Light Reconstruction
Combining Point Clouds Recovered from Multiple Views
Surface Reconstruction from Point Clouds
Elementary Mesh Processing
Related Projects
Conclusion / Q & A