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Reconstruction from Polygon Soup

(GATE-540)

Dr.Çağatay ÜNDEĞER

InstructorMiddle East Technical University, GameTechnologies

&

General ManagerSimBT Inc.

e-mail : cagatay@undeger.com

Game Technologies Program – Middle East Technical University – Spring 2010

Reference: Thomas Funkhouser, Princeton University

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Outline

• Reconstruction

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Goals• Develop 3D Analysis Algorithms:

– Reconstruction– Segmentation– Feature Detection– Labeling– Matching – Classification– Retrielval– Recognition– Clustering

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Goal

• Aim to reconstruct consistent solid geometry and boundary representations for the objects modeled by a set of polygons or line segments of polygons.

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Problems with Input Data

• Model may be non-manifold (no topology):– Missing polygons– Overlapping / intersecting polygons– Unconnected polygons– Unoriented polygons– T-Junctions

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Methods

• Boundary Stitching• Boundary Resampling• Solid Region Labeling

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Boundary Stitching

• Boundary Stitching• Boundary Resampling• Solid Region Labeling

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Boundary Resampling

• Boundary Stitching• Boundary Resampling• Solid Region Labeling

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Boundary Resampling

• Boundary Stitching• Boundary Resampling• Solid Region Labeling

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Solid Region Labeling

• Boundary Stitching• Boundary Resampling• Solid Region Labeling

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Solid Region Labeling

• A Three Step Solid Region Labeling AlgorithmT.M.Murali and T.A.FunkerhouserConsistent Solid and Boundary Representations from Arbitrary Polygonal Data

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Spatial Subdivision• Determine BSP and Cell Complex

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Solid Determination

• Principles:– Adjacent cells sharing a transparent

boundary should have the same solidity– Adjacent cells sharing an opaque boundary

should have opposite solidities– Unbounded cells are not solid

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Model Output

• Output a polygon for each boundary separating a solid cell from a non-solid cell (oriented away from solid)

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Results

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Results