shape modelling - inria · final classification well split hollow blend limb joint funnel tip mount...
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Shape data modelling and analysisas a support in the diagnosis ofvascular diseases
M. Attene, M. Mortara, G. PatanèCNR-IMATI Ge
Speaker: Michela [email protected]
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Shape Modelling
Aquisition Reconstruction Processing …
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Shape Analysis
Characterization Segmentation Structuring …
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In the following…
Tailor
Plumber
Convex Approximation
ShapeAnnotator
with possible applications in the medical field
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Tailor
Use a curvature analysis to compute themain features of a given shape and organizethem into an abstract representation
Automate processes likematching, retrieval, comparisonof shapes.
M.Mortara, G.Patané, M.Spagnuolo, B.Falcidieno, J.Rossignac "Blowing Bubbles for the multiscaledecomposition of triangle meshes" Algorithmica - special issue on shape algorithms. Vol 38, (1), pp. 227-248,Springer, 2003.
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Tailor Label of v at scale i ←
configuration of theintersection between themesh and a sphere havingradius Ri and centred in v.
Curvature
Topology
Geometric attributes
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Classification criteria
Number of connected components: 1,2, 3 or more
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Classification criteria
One intersection curve Curvature characterization:
Sharp
Rounded
Blend
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GC(v)=L/R ∈[0, +∞) On a plane: GC(v)=2π On a spike: GC(v)< 2π →0 On a blend: GC(v)>2π → +∞
No distinction betweenconvex and concave
R
R
α
l
Pl : α = 2πR : 2πα = l / RΣ αi = L / R
Multi-scale curvature on meshes
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Classification criteria
Two intersection curves Relative length characterization:
Cylindrical Lmax≤ 2 Lmin
Conic otherwise
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Classification criteria
Status: One int. Convex Concave
More int. Full Empty
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Final classification
HOLLOWSPLITWELLFUNNELJOINTLIMBBLEND
DIPPITMOUNTTIP
TipTip TipTip
CylindricalCylindricalSaddleSaddle
ConicConic
SmoothSmooth
CylindricalCylindrical
ConcaveConcave
BranchingBranching
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Query Language
Each vertex isdescribed by avector of labels
The ith labelcorresponds to thevertexcharacterization atscale Ri
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Multi-scale Morphological analysis of the cortex
Tailor results
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Curvature-based Skeleton
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ProTailor Parallel implementation on a Linux Beowulf Cluster of
16 PCs 2.66 GHz Pentium IV processor 1 GB of Ram 2 EIDE 80 GB disks interfaced in RAID 0 by Antonella Galizia,IMATI
The scalability of thealgorithm is almostlinear(molecule model, 35MB,31 minutes -> 2 minutes)
M.Mortara, A.Galizia “ProTailor: a paralle operator for extremely fast shape analysis in Bioinformatics applications”in Proceedings of PDP2009, special session on Bioinformatics applications.
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Tailor on volumes
on tetrahedral meshes, computes the spheresurface inside the volume
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Plumber
Segmentation into tubular features and“bodies”
Is based on the Tailor characterization
Works in a multi-scale fashion wrt tubesection size
Computes axis and sections of eachtubular feature
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PlumberThe algorithm works in the following
steps:
Selection of the scale R
Classification of vertices andidentification of seed limb region
Tubular feature extraction
Increase R and repeat
M. Mortara, G. Patané, M. Spagnuolo, B. Falcidieno, and J. Rossignac. Plumber: A Multi-scale Decomposition of 3D Shapes into Tubular Primitives and Bodies, Proc. of SolidModeling and Applications, 2004
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Plumber
A sphere is centredin the barycentre ofthe medial loop.
The sphere rolls in the two possibledirections until a halting condition occurs.
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Plumber
At each step, the sphere generates a newcross section and a new axis point.
Stop when: The tube ends Curve length over threshold Bifurcation
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Results
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Results
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Plumber on Point Clouds
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Identification of human body parts
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Generalization of the hierarchical face clustering(Garland et al. 01)
Automatic generation of a binary tree of clusters,each fitted to one of the availableprimitives: planes, spheres and cylinders At the first step, each triangle is
considered to be a cluster Then, adjacent triangles are
clustered according tocluster-to-primitive fitting
M. Attene, B. Falcidieno, and M. Spagnuolo. Hierarchical Mesh Segmentation based onFitting Primitives. The Visual Computer, 22, 2006
Fitting Primitives
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Segments a shape into a hierarchy of nearlyconvex parts
Works on tetrahedra Applications:
fast region selectionfrom complex models
shape segmentation shape approximation deformation, editing
Hierarchical Convex Approximation
Marco Attene, Michela Mortara, Michela Spagnuolo and Bianca Falcidieno “Hierarchical Convex Approximationof 3D Shapes for Fast Region Selection” Computer Graphics Forum, Vol. 27, No. 5 (SGP'08 Procs.), pp. 1323-1333, 2008
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Region selection The tree of clusters can be traversed
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Complex Selections
Tracking cuttinglines or surfacestrokes can becomplicated Difficult topology Occlusions
Here the heart is connected with multiple vessels and tissues, and is tightly occluded bythe chest, thus selecting it through cutting lines would be rather unpractical.Through our mechanism the selection required just a mouse click and a wheel rotation.
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Annotation Psychological surveys show that humans “understand”
shapes by recognizing interesting sub-parts and theirstructure (Marr 1982, Biederman 1987). Shape Segmentation
For specific contexts, it is possible to describe what these“features” are and how they are structured. Geometric Description of the features Structural Description of the shape Semantic Annotation
cylinder
plane
CylinderIN plane
ThroughHole
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ShapeAnnotator
ShapeA surface mesh
DomainAn OWL ontology
CG ToolsSegmentation Plug-ins
Shape
Annotator
ExpertExpert Knowledge Base
AbstractedShape
A segmented mesh
Instance Instance
User knowledge → usable explicit content
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ShapeAnnotator The ShapeAnnotator is an open-source software
project hosted by sourceforge.net http://shapeannotator.sourceforge.net
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Scenario
Aquisition/reconstruction
Meshsimplification
Part selection
Annotation Analysis
Search/retrievalComparison
Sharing…
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Monitoring shape changes over time
Comparison of the shape of anatomical regionsamong patients
Semantic rendering of anatomical regions andsurgery planning
Analysis, automatic extraction of metadata,automatic or supported annotation of anatomicalregions for future retrieval, comparison and analysisof collected data.
Applications