CGAL 5.3 - CGAL and the Boost Graph Library

Several functions to enlarge or reduce a k-ring selection of vertices, edges, or faces.

## Functions

template<class FaceRange , class FaceGraph , class IsFaceSelectedPMap , class OutputIterator >
OutputIterator CGAL::expand_face_selection (const FaceRange &selection, FaceGraph &fg, unsigned int k, IsFaceSelectedPMap is_selected, OutputIterator out)
augments a selection with faces of fg that are adjacent to a face in selection. More...

template<class FaceRange , class FaceGraph , class IsFaceSelectedPMap , class OutputIterator >
OutputIterator CGAL::reduce_face_selection (const FaceRange &selection, FaceGraph &fg, unsigned int k, IsFaceSelectedPMap is_selected, OutputIterator out)
diminishes a selection of faces from faces adjacent to a non-selected face. More...

template<typename TriangleMesh , typename IsSelectedMap , typename NamedParameters >
void CGAL::regularize_face_selection_borders (TriangleMesh &mesh, IsSelectedMap is_selected, double weight, const NamedParameters &np)
regularizes a selection in order to minimize the length of the border of the selection. More...

template<class HalfedgeRange , class FaceGraph , class OutputIterator >
OutputIterator CGAL::select_incident_faces (const HalfedgeRange &hedges, FaceGraph &fg, OutputIterator out)
Discovers and puts in out all faces incident to the target vertex of a halfedge in hedges. More...

template<class EdgeRange , class HalfedgeGraph , class IsEdgeSelectedPMap , class OutputIterator >
OutputIterator CGAL::expand_edge_selection (const EdgeRange &selection, HalfedgeGraph &fg, unsigned int k, IsEdgeSelectedPMap is_selected, OutputIterator out)
augments a selection with edges of fg that are adjacent to an edge in selection. More...

template<class EdgeRange , class HalfedgeGraph , class IsEdgeSelectedPMap , class OutputIterator >
OutputIterator CGAL::reduce_edge_selection (const EdgeRange &selection, HalfedgeGraph &fg, unsigned int k, IsEdgeSelectedPMap is_selected, OutputIterator out)
diminishes a selection of edges from edges adjacent to a non-selected edge. More...

template<class VertexRange , class HalfedgeGraph , class IsVertexSelectedPMap , class OutputIterator >
OutputIterator CGAL::expand_vertex_selection (const VertexRange &selection, HalfedgeGraph &fg, unsigned int k, IsVertexSelectedPMap is_selected, OutputIterator out)
augments a selection with vertices of fg that are adjacent to a vertex in selection. More...

template<class VertexRange , class HalfedgeGraph , class IsVertexSelectedPMap , class OutputIterator >
OutputIterator CGAL::reduce_vertex_selection (const VertexRange &selection, HalfedgeGraph &fg, unsigned int k, IsVertexSelectedPMap is_selected, OutputIterator out)
diminishes a selection of vertices from vertices adjacent to a non-selected vertex. More...

template<class TriangleMesh , class FaceRange , class IsSelectedMap >
void CGAL::expand_face_selection_for_removal (const FaceRange &faces_to_be_deleted, TriangleMesh &tm, IsSelectedMap is_selected)
Expands a selection of faces so that their removal does not create any non manifold vertex. More...

## ◆ expand_edge_selection()

template<class EdgeRange , class HalfedgeGraph , class IsEdgeSelectedPMap , class OutputIterator >
 OutputIterator CGAL::expand_edge_selection ( const EdgeRange & selection, HalfedgeGraph & fg, unsigned int k, IsEdgeSelectedPMap is_selected, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

augments a selection with edges of fg that are adjacent to an edge in selection.

This process is applied k times considering all edges added in the previous steps. Two edges are said to be adjacent if they are incident to the same face or vertex. Each new edge added in the selection is added exactly once in out.

Template Parameters
 EdgeRange a range of edge descriptors, model of Range. Its iterator type is InputIterator. FaceGraph a model of FaceGraph. IsEdgeSelectedPMap a model of ReadWritePropertyMap with boost::graph_traits::edge_descriptor as key type and bool as value type. OutputIterator an output iterator accepting edge descriptors.
Parameters
 selection the initial selection of edges that will be expanded. fg the graph containing the selected edges. k the number of times the expansion procedure is iteratively applied. is_selected indicates if an edge is part of the selection. It is updated by the function to accommodate new edges added to the selection. out new edges added to the selection are added exactly once in out.

## ◆ expand_face_selection()

template<class FaceRange , class FaceGraph , class IsFaceSelectedPMap , class OutputIterator >
 OutputIterator CGAL::expand_face_selection ( const FaceRange & selection, FaceGraph & fg, unsigned int k, IsFaceSelectedPMap is_selected, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

augments a selection with faces of fg that are adjacent to a face in selection.

This process is applied k times considering all faces added in the previous steps. Two faces are said to be adjacent if they share a vertex or an edge. Each new face added in the selection is added exactly once in out.

Template Parameters
 FaceRange a range of face descriptors, model of Range. Its iterator type is InputIterator. FaceGraph a model of FaceGraph. IsFaceSelectedPMap a model of ReadWritePropertyMap with boost::graph_traits::face_descriptor as key type and bool as value type. OutputIterator an output iterator accepting face descriptors.
Parameters
 selection the initial selection of faces that will be expanded. fg the graph containing the selected faces. k the number of times the expansion procedure is iteratively applied. is_selected indicates if a face is part of the selection. It is updated by the function to accommodate new faces added to the selection. out new faces added to the selection are added exactly once in out.

## ◆ expand_face_selection_for_removal()

template<class TriangleMesh , class FaceRange , class IsSelectedMap >
 void CGAL::expand_face_selection_for_removal ( const FaceRange & faces_to_be_deleted, TriangleMesh & tm, IsSelectedMap is_selected )

#include <CGAL/boost/graph/selection.h>

Expands a selection of faces so that their removal does not create any non manifold vertex.

For each vertex that is incident to a selected face, we turn around that vertex and check if there is exactly one set of consecutive selected faces. If not, additional faces around that vertex are selected to match this condition.

Template Parameters
 TriangleMesh a model of FaceGraph that is triangulated. FaceRange a range of boost::graph_traits::face_descriptor, with an iterator type model of ForwardIterator. IsSelectedMap a model of ReadWritePropertyMap with boost::graph_traits::face_descriptor as key and bool as value.
Parameters
 tm the triangle mesh. faces_to_be_deleted the range of selected faces. is_selected a property map containing the selected-or-not status of each face of tm. It must associate true to each face of faces_to_be_deleted and false to any other face of tm. It will be modified if the face selection must be expanded.

## ◆ expand_vertex_selection()

template<class VertexRange , class HalfedgeGraph , class IsVertexSelectedPMap , class OutputIterator >
 OutputIterator CGAL::expand_vertex_selection ( const VertexRange & selection, HalfedgeGraph & fg, unsigned int k, IsVertexSelectedPMap is_selected, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

augments a selection with vertices of fg that are adjacent to a vertex in selection.

This process is applied k times considering all vertices added in the previous steps. Two vertices are said to be adjacent if they are part of the same face. Each new vertex added in the selection is added exactly once in out.

Template Parameters
 VertexRange a range of vertex descriptors, model of Range. Its iterator type is InputIterator. FaceGraph a model of FaceGraph. IsVertexSelectedPMap a model of ReadWritePropertyMap with boost::graph_traits::vertex_descriptor as key type and bool as value type. OutputIterator an output iterator accepting vertex descriptors.
Parameters
 selection the initial selection of vertices that will be expanded. fg the graph containing the selected vertices. k the number of times the expansion procedure is iteratively applied. is_selected indicates if a vertex is part of the selection. It is updated by the function to accommodate new vertices added to the selection. out new vertices added to the selection are added exactly once in out.

## ◆ reduce_edge_selection()

template<class EdgeRange , class HalfedgeGraph , class IsEdgeSelectedPMap , class OutputIterator >
 OutputIterator CGAL::reduce_edge_selection ( const EdgeRange & selection, HalfedgeGraph & fg, unsigned int k, IsEdgeSelectedPMap is_selected, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

diminishes a selection of edges from edges adjacent to a non-selected edge.

This process is applied k times considering all edges removed in the previous steps. Two edges are said to be adjacent if they are incident to the same face or vertex. Each edge removed from the selection is added exactly once in out.

Template Parameters
 EdgeRange a range of edge descriptors, model of Range. Its iterator type is InputIterator. FaceGraph a model of FaceGraph. IsEdgeSelectedPMap a model of ReadWritePropertyMap with boost::graph_traits::edge_descriptor as key type and bool as value type. OutputIterator an output iterator accepting edge descriptors.
Parameters
 selection the initial selection of edges that will be reduced. fg the graph containing the selected edges. k the number of times the reduction procedure is iteratively applied. is_selected indicates if an edge is part of the selection. It is updated by the function to accommodate edges removed from the selection. out edges removed from the selection are added exactly once in out.

## ◆ reduce_face_selection()

template<class FaceRange , class FaceGraph , class IsFaceSelectedPMap , class OutputIterator >
 OutputIterator CGAL::reduce_face_selection ( const FaceRange & selection, FaceGraph & fg, unsigned int k, IsFaceSelectedPMap is_selected, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

diminishes a selection of faces from faces adjacent to a non-selected face.

This process is applied k times considering all faces removed in the previous steps. Two faces are said to be adjacent if they share a vertex or an edge. Each face removed from the selection is added exactly once in out.

Template Parameters
 FaceRange a range of face descriptors, model of Range. Its iterator type is InputIterator. FaceGraph a model of FaceGraph. IsFaceSelectedPMap a model of ReadWritePropertyMap with boost::graph_traits::face_descriptor as key type and bool as value type. OutputIterator an output iterator accepting face descriptors.
Parameters
 selection the initial selection of faces that will be expanded. fg the graph containing the selected faces. k the number of times the reduction procedure is iteratively applied. is_selected indicates if a face is part of the selection. It is updated by the function to accommodate faces removed from the selection. out faces removed from the selection are added exactly once in out.

update is-selected attribute and output iterator

## ◆ reduce_vertex_selection()

template<class VertexRange , class HalfedgeGraph , class IsVertexSelectedPMap , class OutputIterator >
 OutputIterator CGAL::reduce_vertex_selection ( const VertexRange & selection, HalfedgeGraph & fg, unsigned int k, IsVertexSelectedPMap is_selected, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

diminishes a selection of vertices from vertices adjacent to a non-selected vertex.

This process is applied k times considering all vertices removed in the previous steps. Two vertices are said to be adjacent if they are part of the same face. Each vertex removed from the selection is added exactly once in out.

Template Parameters
 VertexRange a range of vertex descriptors, model of Range. Its iterator type is InputIterator. FaceGraph a model of FaceGraph. IsVertexSelectedPMap a model of ReadWritePropertyMap with boost::graph_traits::vertex_descriptor as key type and bool as value type. OutputIterator an output iterator accepting vertex descriptors.
Parameters
 selection the initial selection of vertices that will be reduced. fg the graph containing the selected vertices. k the number of times the reduction procedure is iteratively applied. is_selected indicates if a vertex is part of the selection. It is updated by the function to accommodate vertices removed from the selection. out vertices removed from the selection are added exactly once in out.

## ◆ regularize_face_selection_borders()

template<typename TriangleMesh , typename IsSelectedMap , typename NamedParameters >
 void CGAL::regularize_face_selection_borders ( TriangleMesh & mesh, IsSelectedMap is_selected, double weight, const NamedParameters & np )

#include <CGAL/boost/graph/selection.h>

regularizes a selection in order to minimize the length of the border of the selection.

The alpha expansion algorithm is used (see CGAL::alpha_expansion_graphcut()) using the length of the edge between two faces as the edge cost and the initial selected/unselected property of a face as the face cost.

If prevent_unselection is set to true, the cost of unselecting a face is set to infinity, which forces the regularization to only select new faces and ensures that the regularization keeps all selected faces.

Template Parameters
 TriangleMesh a model of FaceGraph IsSelectedMap a model of ReadWritePropertyMap with boost::graph_traits::face_descriptor as key type and bool as value type NamedParameters a sequence of named parameters
Parameters
 mesh the mesh containing the selected faces. is_selected indicates if a face is part of the selection. It is updated by the function to accommodate faces added or removed from the selection. weight sets the tradeoff between data fidelity and regularity, ranging from 0 (no regularization at all, selection is left unaltered) to 1 (maximum regularization, usually selects or unselects everything so that the length of the border of the selection is 0) np an optional sequence of Named Parameters among the ones listed below
Optional Named Parameters
 a property map associating points to the vertices of tm Type: a class model of ReadWritePropertyMap with boost::graph_traits::vertex_descriptor as key type and Point_3 as value type Default: boost::get(CGAL::vertex_point, tm) Extra: If this parameter is omitted, an internal property map for CGAL::vertex_point_t must be available in TriangleMesh. a property map associating to each face of tm a unique index between 0 and num_faces(tm) - 1 Type: a class model of ReadablePropertyMap with boost::graph_traits::face_descriptor as key type and std::size_t as value type Default: an automatically indexed internal map Boolean used to indicate if selection can be only extended or if it can also be shrinked. Type: bool Default: false Extra: The geometric traits class must be compatible with the vertex point type. an instance of a geometric traits class Type: a class model of Kernel Default: a CGAL Kernel deduced from the point type, using CGAL::Kernel_traits Extra: The geometric traits class must be compatible with the vertex point type.
Examples:
BGL_graphcut/face_selection_borders_regularization_example.cpp.

## ◆ select_incident_faces()

template<class HalfedgeRange , class FaceGraph , class OutputIterator >
 OutputIterator CGAL::select_incident_faces ( const HalfedgeRange & hedges, FaceGraph & fg, OutputIterator out )

#include <CGAL/boost/graph/selection.h>

Discovers and puts in out all faces incident to the target vertex of a halfedge in hedges.

Faces are put exactly once in out.

Template Parameters
 HalfedgeRange a range of halfedge descriptors, model of Range. Its iterator type is InputIterator. HalfedgeGraph a model of HalfedgeGraph. OutputIterator an output iterator accepting face descriptors.
Parameters
 hedges the range a halfedge descriptors consider during the face selection. fg the graph containing the input halfedges. out faces added to the selection are added exactly once in out.