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Published byCharles Andersen Modified over 3 years ago

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Level Sets Framework Refactoring Arnaud Gelas, Kishore Mosaliganti, Sean Megason Harvard Medical School

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Framework Enhancements Different representation Different domains Multiphase ( > 1 levelset) Multichannel ( > 1 channel) General PixelType (vector, tensor, RGB) Term mashup ( geodesic, internal energy, etc ) Dynamic interactions Stopping and reinitialization criteria

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Level Set Domain Definition – Level Set Domain refers to the subset where the Level Set Function is defined No restriction on topological dimension – Image – Volumetric Mesh – Surface Mesh – Curve – Point Set – Etc… Courtesy of Peter Karasev Courtesy of Kush Varshney

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Level Set Representation Discrete – Dense – Narrow-band Parametric (Continuous) – RBF based Images Point-Set – Spline based Images

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Level Set Support Definition – Level Set Support refers to the subset of the Domain where the level set function is currently sampled and being evolved For instance – dense case: The level set support could be region of interest, or the whole domain – narrow band: The level set support is changing at each iteration The level set support is next to the 0 level set [Mosaliganti09] 0 level-set support domain

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Level Set Equation Terms Term class corresponds to one term in the level set evolution equation – Provide a scalar for a given location – Weight provided by the user – A Name provided by the developer All Terms are stored in containers, where – Terms can be added – Terms can be removed dynamically at run-time

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Any PixelType Independent of the underlying data type thanks to the introduction of the term container – Scalars – Vectors – Tensors Needs to be taken care In the term implementation! Needs to be taken care In the term implementation!

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Level Set Evolution Implementation depends – on the representation of the level sets Discrete Parametric – on the scheme use to solve Explicit Semi implicit Topologically constrained

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Multiphase # level sets N > 1 – Useful in microscopy Level set function container – Add / Remove level set functions Terms container – Add interactions between levelsets Geometrical constraints [Mosaliganti09]

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Stopping criterion Default implementation – Number of Iterations – RMS Change User can provide his own stopping criterion

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Reinitialization Filters – Provided by the user Depends on the level set representation – Periodically applied User-specified

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Multithread Strategies Depends on the number of level sets – if N > number of cores, the priority is given to the level set iteration – else the priority is given to the support iteration

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Visualization VTK widgets 0- Level Set + 2D image 0- Level Set in 3D Level Set Function in 2D

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Wrappers Provide default Traits Provide wrapper classes with API close to ITKv3 implementation for existing level set filters

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