COMP4610/8610 Computer Grahpics
Tutorial 4
HW3 Mesh Processing
Haorui Ji
Haorui.ji@anu.edu.au
28/Mar/2024
Agenda
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01 Overview
02 Task1
03 Task2
04 Q & A
01 Overview
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Overview
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• Topic: Mesh processing
• Totally 2 tasks.
• Take 12% of the final mark.
• No more report template and marking criteria.
• Declaration of Originality as the first page of report.
02 Task1 Half-Edge Data Structure
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Half-Edge Data Structure
Task1 Half-Edge Data Structure
• Represent the mesh in the memory by a half-edge data structure.
• Implement traversal:
• Traverse all half edges that points away from given vertex
• Traverse all member vertices of given face
• Compute its topology properties (genus number).
• Compute its volume and surface areas.
• Compute the average degree of all the vertices.
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Task1 Half-Edge Data Structure
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In your report:
•Use the two OBJ meshes provided in ”model”
folder (bigguy2.obj, teeth.obj) to show the results.
•Put a screenshot of the mesh represented by half-
edge data structure
•Brief introduction describing the process of your
conversion (a pseudo-code will be best for better
clarification).
•Show the geometric properties (e.g. number of
vertices, faces, half-edges and edges) of the mesh
as well as the topology computation results.
03 Task2 Mesh Simplification
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Task2 Mesh Simplification
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Pair Contraction
Reference: https://www.cs.cmu.edu/~./garland/Papers/quadrics.pdf
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Quadratic Error Metric
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Edge Contraction (Edge Collapse)
Task2 Mesh Simplification
• Compute the coefficient vector q that represent the quadratic
coefficient of this vertex.
• Compute the following results for edge (v1, v2)
• Optimal contraction target v*
• The quadratic error metrics E(v∗) which is the combined
quadratic for the union of v1, v2. Note that the computed
results will become the cost of contracting this edge.
• Perform edge-collapse
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Task2 Mesh Simplification
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In your report:
• Use the two OBJ meshes provided
in ”model” folder (bigguy2.obj, teeth.obj)
to show the results.
• Display the original mesh as well as the
simplified mesh with MeshLab or Blender.
• In addition, take the screenshot of the
mesh information as well as the
verification results from the terminal
output of task2.cpp to demonstrate the
correctness of your implementation.
04 Q&A
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THANK YOU
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