CGAL::Feature_graph::Detect_sharp_features_on_surface< K > Struct Template Reference

#include <CGAL/Feature_graph/detect_sharp_features.h>

Definition

template<typename K>
struct CGAL::Feature_graph::Detect_sharp_features_on_surface< K >

Detector for sharp feature extraction in surfaces.

It constructs a feature graph model of VertexAndEdgeListGraph.

Template Parameters

K	the requirements for the geometric objects, model of Kernel.

See also

Detect_sharp_features_on_labeled_image

Types
typedef K::Point_3	Point_3
	Output feature graph point type.
typedef std::size_t	Size
	Natural number type.
typedef K::FT	FT
	Numerical type.

Detector
template<typename PolygonMesh, typename NamedParameters = CGAL::parameters::Default_named_parameters>
unspecified_type	operator() (const PolygonMesh &pmesh, const NamedParameters &np=parameters::default_values()) const
	detects and constructs the feature graph from a surface

Member Function Documentation

operator()()

template<typename K>

template<typename PolygonMesh, typename NamedParameters = CGAL::parameters::Default_named_parameters>

unspecified_type CGAL::Feature_graph::Detect_sharp_features_on_surface< K >::operator()	(	const PolygonMesh &	pmesh,
		const NamedParameters &	np = parameters::default_values() ) const

detects and constructs the feature graph from a surface

The feature graph has polylines that lie on the sharp features of the surface.

Template Parameters

PolygonMesh

a model of FaceListGraph that represents a surface mesh.

Parameters

pmesh

a polygon mesh from where the sharp features are extracted.

np

an optional sequence of Named Parameters among the ones listed below: Optional Named Parameters sharpness_estimator an estimator model of SharpnessEstimator. See Sharpness Estimator for available estimators. Default: CGAL::Feature_graph::Surface_sharpness_estimator(pmesh) line_distance_threshold the threshold on the distance between lines. In the regularization step, if the maximum distance of a line to another line is less than this threshold, then the line is collapsed. It can be a constant or a scalar field that return the threshold at a point on the surface. If it is a scalar field, it must implement template <typename DimensionTag, typename Descriptor> FT operator()(const Point_3& point_in_space, const Descriptor& element_descriptor, const PolygonMesh& pmesh) const The type DimensionTag represents the element type, it can either be CGAL::Dimension_tag<0>, CGAL::Dimension_tag<1> or CGAL::Dimension_tag<2>, which represent either a vertex element, an edge element, or a facet element respectively. The type Descriptor is either a vertex_descriptor, halfedge_descriptor or face_descriptor and is set respectivelly to the DimensionTag. Default: FT(0.0) Extra: This parameter sets a baseline distance and is overridden by the parameters parameters::isthmus_line_distance_threshold, parameters::simple_line_distance_threshold and parameters::corner_line_distance_threshold if they are set. isthmus_line_distance_threshold the threshold on the distance between an isthmus line and any line. An isthmus line is bounded by a corner that is incident to only the same line. In the regularization step, if the maximum distance of a line to another line is less than this threshold, then the line is collapsed. It can be a constant or a scalar field that return the threshold at a point on the surface. If it is a scalar field, it must implement template <typename DimensionTag, typename Descriptor> FT operator()(const Point_3& point_in_space, const Descriptor& element_descriptor, const PolygonMesh& pmesh) const See the description of parameters::line_distance_threshold for more details on this scalar field. Default: FT(-1.0) Extra: Negative values implies the use of the parameter parameters::line_distance_threshold. simple_line_distance_threshold the threshold on the distance between a simple line and any line. A simple line is a line that can be removed without splitting the graph of its neighbors. In the regularization step, if the maximum distance of a line to another line is less than this threshold, then the line is collapsed. It can be a constant or a scalar field that return the threshold at a point on the surface. If it is a scalar field, it must implement template <typename DimensionTag, typename Descriptor> FT operator()(const Point_3& point_in_space, const Descriptor& element_descriptor, const PolygonMesh& pmesh) const See the description of parameters::line_distance_threshold for more details on this scalar field. Default: FT(-1.0) Extra: Negative values implies the use of the parameter parameters::line_distance_threshold. corner_line_distance_threshold the threshold on the distance between a corner line and any line. A corner line is neither isthmus nor simple. In the regularization step, if the maximum distance of a line to another line is less than this threshold, then the line is collapsed. It can be a constant or a scalar field that return the threshold at a point on the surface. If it is a scalar field, it must implement template <typename DimensionTag, typename Descriptor> FT operator()(const Point_3& point_in_space, const Descriptor& element_descriptor, const PolygonMesh& pmesh) const See the description of parameters::line_distance_threshold for more details on this scalar field. Default: FT(-1.0) Extra: Negative values implies the use of the parameter parameters::line_distance_threshold. do_optimize a boolean indicating if the optimization step is called. Default: true maximum_number_of_iterations the maximum number of iterations of the gradient descent during the optimization step. Default: Size(20) start_step_size the step size at the first iteration of the gradient descent during the optimization step. Default: FT(0.0) end_step_size the step size at the last iteration of the gradient descent during the optimization step. Default: FT(0.0) mininmum_energy_delta the minimum energy change to stop the gradient descent iterations during the optimization step. Default: FT(1.e-3) collapse_distance the distance to collapse adjacent points in a line during the gradient descent of the optimization step. Default: FT(0.0) smoothing_factor the smoothing factor of the energy of the optimization step. 0 means no smoothing, 1 means that the energy will consider smoothing with the same weight as the displacement toward the sharp features of the surface. Default: FT(1.0) normal_refinement_distance the distance to refine the normals of elements near the sharp features during the optimization step. Default: FT(0.0) plane_detection_distance the distance to collect elements near the sharp features to determine the adjacent planes during the optimization step. Default: FT(0.0) normal_estimator an estimator to evaluate the normals on elements. Default: CGAL::Feature_graph::Surface_normal_estimator(pmesh) point_to_element_output_map an output property map that will be filled if supplied. It allow retrieving of the surface element where a feature graph point is embedded. It must be a model of WritablePropertyMap, and must implement put(output_pmap, feature_vertex_descriptor, facet_descriptor) where the key type is the vertex_descriptor of the feature graph, and the value type is the facet_descriptor of the polygon mesh. Default: parameters::default()

Returns

a graph model of VertexAndEdgeListGraph containing the constructed features.