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Assessment of Mesh Simplification Algorithm Quality. Michaël ROY, Frédéric NICOLIER , Sebti FOUFOU , Frédéric TRUCHETET, Andreas KOSCHAN, Mongi ABIDI. Outline. Introduction Mesh Mesh simplification Quality metrics Quality assessment Geometric deviation Attribute deviation Results
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Assessment of Mesh Simplification Algorithm Quality Michaël ROY, Frédéric NICOLIER, Sebti FOUFOU, Frédéric TRUCHETET, Andreas KOSCHAN, Mongi ABIDI
Outline • Introduction • Mesh • Mesh simplification • Quality metrics • Quality assessment • Geometric deviation • Attribute deviation • Results • Conclusion and future work
Mesh • Geometrical data • Vertices • Faces • Appearance data • Colors • Normals • Texture coordinates
Mesh Synthetic mesh Digital elevation map
Mesh simplification • High quality / big meshes • High vertex & face number • Motivations • Interactive manipulation • Low space storage • Quick network transmission
Mesh simplification 60 000 faces Original mesh Simplified mesh 1 000 faces
Quality metrics • Geometric error METRO -P. Cignoni, C. Rocchini, R. Scopigno (1998)
Quality metrics • Geometric error - METRO 1998 • Point-to-surface distance P: a point S: a surface d(p,p’) : Euclidian distance between two points in R3
Quality metrics • Texture deviation - Cohen (1998) Original mesh Simplified mesh
Quality metrics • Texture deviation- Cohen (1998) S1 etS2: two surfaces pi: a point onS1 F(p) = (s,t) : texture coordinates of the point p F-1(s,t) = p : point with texture coordinates(s,t)
Quality metrics • Texture deviation- Cohen (1998) If no real texture deviation Cohen’s texture deviation = geometric deviation Conclusion: not suitable for assessing mesh simplification quality
Quality assessment Two measurements • Geometric deviation • Attribute deviation
Geometric deviation M1et M2: two meshes S1 etS2: their respective surfaces pi: a point on surfaceS1
Attribute deviation Original mesh Simplified mesh
Attribute deviation M1et M2: two meshes S1 etS2: their respective surface pi: a point on surfaceS1 A(p) = av: attribute at point p N(p,S) = pc: nearest pointto point pon surface S
Implementation • Find the nearest point • Uniform grid • Uniform distributed point on surface • Surface sampling • Deviation texture • Texture packing
Results • Mesh simplification algorithm used • Qslim 2.0 (Garland 98) • Jade 2.1 (Ciampalini, Cignoni 97) • ProgMesh 1.2 (Hoppe 96)
Results • Test mesh 53 696 faces 1 073 faces
Results QSlim Jade ProgMesh Geometric deviation Normal deviation
Results Original Simplified (L) Simplified (H) Geometric Cohen (L) Cohen (H) Attribute (L) Attribute (H)
Conclusion and future work • Quality assessment • Geometric deviation • Attributes deviation • Results on three simplification algorithms • Software: http://meshdev.sourceforge.net • Future : • Adapt attribute deviation to the color space • Estimate triangulation quality
Assessment of Mesh Simplification Algorithm Quality Michaël ROY, Frédéric NICOLIER, Sebti FOUFOU, Frédéric TRUCHETET, Andreas KOSCHAN, Mongi ABIDI