Framework for segmentation of cylindrical structures using two dimensional hybrid models
First Claim
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1. A method of modeling a structure comprising the steps of:
- initializing a parametric component of a hybrid model from a vohumetric image, the volumetric image comprising image planes;
creating starting points for two dimensional segmentations at intersections between the parametric component and the image planes;
segmenting a boundary of the structure by applying active contours;
sampling the active contours to create a dataset;
parametrically and locally fitting the hybrid model to the dataset to represent the structure;
reducing a number of iterations to fit the hybrid model by introducing a finite element shape function for distributing forces to draw the hybrid model to data of the dataset wherein the forces include data forces and smoothing forces;
introducing a scale factor to weight data locations from the dataset to provide a scaled force vector for more rapidly fitting the hybrid model to the dataset; and
combining the data forces and the smoothing forces by introducing a trade-off parameter for balancing data forces against smoothing forces and thereby providing increased stability to the fitting of the hybrid model.
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Abstract
A method of modeling a structure comprises the steps of initializing a parametric component of a hybrid model from a volumetric image, the volumetric image comprising image planes, creating starting points for two dimensional segmentations at intersections between the parametric component and the image planes, segmenting a boundary of the structure by applying active contours, sampling the active contours to create a dataset and parametrically and locally fitting the hybrid model to the dataset to represent the structure.
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Citations
25 Claims
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1. A method of modeling a structure comprising the steps of:
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initializing a parametric component of a hybrid model from a vohumetric image, the volumetric image comprising image planes;
creating starting points for two dimensional segmentations at intersections between the parametric component and the image planes;
segmenting a boundary of the structure by applying active contours;
sampling the active contours to create a dataset;
parametrically and locally fitting the hybrid model to the dataset to represent the structure;
reducing a number of iterations to fit the hybrid model by introducing a finite element shape function for distributing forces to draw the hybrid model to data of the dataset wherein the forces include data forces and smoothing forces;
introducing a scale factor to weight data locations from the dataset to provide a scaled force vector for more rapidly fitting the hybrid model to the dataset; and
combining the data forces and the smoothing forces by introducing a trade-off parameter for balancing data forces against smoothing forces and thereby providing increased stability to the fitting of the hybrid model. - View Dependent Claims (2, 3, 4, 5)
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3. The method of modeling a structure as recited in claim 1 wherein the shape function is represented by a formula:
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4. The method of modeling a structure as recited in claim 1 wherein the scale factor is represented by a formula:
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where i is a set of all nodes and M is a number of datapoints associated with a node i,j which has a closest point to an element s(j) in element coordinates and Ni is a shape function for node i with respect to element s(j).
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5. The method of modeling a structure as recited in claim 1 wherein the dataset represents three dimensions.
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6. A method of modeling branching cylindrical structures comprising the steps of:
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initializing a parametric component of a three dimensional hybrid model from a volumetric image of the branching structure;
the volumetric image comprising image planes;
creating starting points for two dimensional segmentations at intersections between the branching structure and the image planes;
segmenting the branching structure by applying two dimensional active contours to the image planes to more accurately depict features of the branching structure;
sampling the active contours to create a dataset;
parametrically and locally fitting the hybrid model to the dataset to represent the branching structure by applying forces to draw the hybrid model onto the data of the dataset;
reducing a number of iterations to fit the hybrid model by introducing a finite element shape function for distributing forces to draw the hybrid to data of the dataset;
introducing a scale factor to weight data locations from the dataset to provide a scaled force vector for more rapidly fitting the hybrid model to the dataset, wherein the scale factor is represented by the formula;
where i is a set of all nodes and M is a number of datapoints associated with a node i,j which has a closest point to an element s(j) in element coordinates and Ni is a shape function for node i with respect to element s(j).- View Dependent Claims (7, 8, 9, 10, 11)
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9. The method of modeling branching cylindrical structures as recited in claim 11 wherein the shape function is represented by the formula:
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10. The method of modeling branching cylindrical structures as recited in claim 6 wherein the forces include data forces and smoothing forces.
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11. The method of modeling a structure as recited in claim 10 further comprising the step of combining the data forces and the smoothing forces by introducing a trade-off parameter τ
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12. A method of modeling a structure, comprising the steps of:
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initializing a parametric component of a hybrid model from a volumetric image, the volumetric image comprising image planes;
creating starting points for two dimensional segmentations at intersections between the parametric component and the image planes;
segmenting a boundary of the structure by applying active contours;
sampling the active contours to create a dataset;
parametrically and locally fitting the hybrid model to the dataset to represent the structure;
reducing a number of iterations to fit the hybrid model by introducing a finite element shape function for distributing forces to draw the hybrid model to data of the dataset, wherein the shape function is represented by a formula;
- View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method of modeling a structure comprising the steps of:
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initializing a parametric component of a hybrid model from a volumetric image, the volumetric image comprising image planes;
creating starting points for two dimensional segmentations at intersections between the parametric component and the image planes;
segmenting a boundary of the structure by applying active contours;
sampling the active contours to create a dataset;
parametrically and locally fitting the hybrid model to the dataset to represent the structure;
reducing a number of iterations to fit the hybrid model by introducing a finite element shape function for distributing forces to draw the hybrid model to data of the dataset, wherein the shape function is represented by a formula;
- View Dependent Claims (20, 21, 22, 23, 24, 25)
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Specification