Ilker O. Yaz and Sébastien Loriot
This package provides a method to generate a segmentation of a triangulated surface mesh. The algorithm first computes the Shape Diameter Function (SDF) for all facets and applies a graph-cut based algorithm over these values. Low level functions are provided to replace any intermediate step by a custom one.
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| template<class TriangleMesh , class SDFPropertyMap , class PointPropertyMap = typename boost::property_map<TriangleMesh, boost::vertex_point_t>::type, class GeomTraits = typename Kernel_traits<typename boost::property_traits<PointPropertyMap>::value_type>::Kernel> |
| std::pair< double, double > | CGAL::sdf_values (const TriangleMesh &triangle_mesh, SDFPropertyMap sdf_values_map, double cone_angle=2.0/3.0 *CGAL_PI, std::size_t number_of_rays=25, bool postprocess=true, PointPropertyMap ppmap=PointPropertyMap(), GeomTraits traits=GeomTraits()) |
| | Function computing the Shape Diameter Function over a surface mesh. More...
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| template<class TriangleMesh , class SDFPropertyMap > |
| std::pair< double, double > | CGAL::sdf_values_postprocessing (const TriangleMesh &triangle_mesh, SDFPropertyMap sdf_values_map) |
| | Function post-processing raw SDF values computed per facet. More...
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| template<class TriangleMesh , class SDFPropertyMap , class SegmentPropertyMap , class PointPropertyMap = typename boost::property_map<TriangleMesh, boost::vertex_point_t>::type, class GeomTraits = typename Kernel_traits<typename boost::property_traits<PointPropertyMap>::value_type>::Kernel> |
| std::size_t | CGAL::segmentation_from_sdf_values (const TriangleMesh &triangle_mesh, SDFPropertyMap sdf_values_map, SegmentPropertyMap segment_ids, std::size_t number_of_clusters=5, double smoothing_lambda=0.26, bool output_cluster_ids=false, PointPropertyMap ppmap=PointPropertyMap(), GeomTraits traits=GeomTraits()) |
| | Function computing the segmentation of a surface mesh given an SDF value per facet. More...
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| template<class TriangleMesh , class SegmentPropertyMap , class PointPropertyMap = typename boost::property_map<TriangleMesh, boost::vertex_point_t>::type, class GeomTraits = typename Kernel_traits<typename boost::property_traits<PointPropertyMap>::value_type>::Kernel> |
| std::size_t | CGAL::segmentation_via_sdf_values (const TriangleMesh &triangle_mesh, SegmentPropertyMap segment_ids, double cone_angle=2.0/3.0 *CGAL_PI, std::size_t number_of_rays=25, std::size_t number_of_clusters=5, double smoothing_lambda=0.26, bool output_cluster_ids=false, PointPropertyMap ppmap=PointPropertyMap(), GeomTraits traits=GeomTraits()) |
| | Function computing the segmentation of a surface mesh. More...
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template<class TriangleMesh , class SDFPropertyMap , class PointPropertyMap = typename boost::property_map<TriangleMesh, boost::vertex_point_t>::type, class GeomTraits = typename Kernel_traits<typename boost::property_traits<PointPropertyMap>::value_type>::Kernel>
| std::pair<double, double> CGAL::sdf_values |
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const TriangleMesh & |
triangle_mesh, |
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SDFPropertyMap |
sdf_values_map, |
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double |
cone_angle = 2.0 / 3.0 * CGAL_PI, |
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std::size_t |
number_of_rays = 25, |
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bool |
postprocess = true, |
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PointPropertyMap |
ppmap = PointPropertyMap(), |
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GeomTraits |
traits = GeomTraits() |
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) |
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template<class TriangleMesh , class SDFPropertyMap >
| std::pair<double, double> CGAL::sdf_values_postprocessing |
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const TriangleMesh & |
triangle_mesh, |
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SDFPropertyMap |
sdf_values_map |
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) |
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#include <CGAL/mesh_segmentation.h>
Function post-processing raw SDF values computed per facet.
Post-processing steps applied :
- Facets with -1 SDF values are assigned the average SDF value of their edge-adjacent neighbors. If there is still a facet having -1 SDF value, the minimum valid SDF value assigned to it. Note that this step is not inherited from the paper. The main reason for not assigning 0 to facets with no SDF values (i.e. -1) is that it can obstruct log-normalization process which takes place at the beginning of
CGAL::segmentation_from_sdf_values().
- SDF values are smoothed with bilateral filtering.
- SDF values are linearly normalized between [0,1].
See the section Post-processing of Raw SDF Values for more details.
- Precondition
is_triangle_mesh(triangle_mesh) -
Raw values should be greater or equal to 0. -1 indicates when no value could be computed
- Template Parameters
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| TriangleMesh | a model of FaceListGraph |
| SDFPropertyMap | a ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::face_descriptor as key and double as value type |
- Parameters
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| triangle_mesh | surface mesh on which SDF values are computed |
| [in,out] | sdf_values_map | the SDF value of each facet |
- Returns
- minimum and maximum SDF values before linear normalization
template<class TriangleMesh , class SDFPropertyMap , class SegmentPropertyMap , class PointPropertyMap = typename boost::property_map<TriangleMesh, boost::vertex_point_t>::type, class GeomTraits = typename Kernel_traits<typename boost::property_traits<PointPropertyMap>::value_type>::Kernel>
| std::size_t CGAL::segmentation_from_sdf_values |
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const TriangleMesh & |
triangle_mesh, |
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SDFPropertyMap |
sdf_values_map, |
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SegmentPropertyMap |
segment_ids, |
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std::size_t |
number_of_clusters = 5, |
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double |
smoothing_lambda = 0.26, |
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bool |
output_cluster_ids = false, |
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PointPropertyMap |
ppmap = PointPropertyMap(), |
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GeomTraits |
traits = GeomTraits() |
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) |
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#include <CGAL/mesh_segmentation.h>
Function computing the segmentation of a surface mesh given an SDF value per facet.
This function fills a property map which associates a segment-id (in [0, number of segments -1]) or a cluster-id (in [0, number_of_clusters -1]) to each facet. A segment is a set of connected facets which are placed under the same cluster (see fig__Cluster_vs_segment).
- Note
- Log-normalization is applied on
sdf_values_map before segmentation. As described in the original paper [5], this normalization is done to preserve thin parts of the mesh by increasing the distance between smaller SDF values and reducing it between larger ones.
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There is no direct relation between the parameter
number_of_clusters and the final number of segments after segmentation. However, setting a large number of clusters will result in a detailed segmentation of the mesh with a large number of segments.
- Precondition
is_triangle_mesh(triangle_mesh) -
number_of_clusters > 0
- Template Parameters
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| TriangleMesh | a model of FaceListGraph |
| SDFPropertyMap | a ReadablePropertyMap with boost::graph_traits<TriangleMesh>::face_descriptor as key and double as value type |
| SegmentPropertyMap | a ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::face_descriptor as key and std::size_t as value type |
| GeomTraits | a model of SegmentationGeomTraits |
| PointPropertyMap | a ReadablePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key and GeomTraits::Point_3 as value type. |
- Parameters
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| triangle_mesh | surface mesh corresponding to the SDF values |
| sdf_values_map | the SDF value of each facet between [0-1] |
| [out] | segment_ids | the segment or cluster id of each facet |
| number_of_clusters | number of clusters for the soft clustering |
| smoothing_lambda | factor which indicates the importance of the surface features for the energy minimization. It is recommended to choose a value in the interval [0,1]. See the section Hard clustering for more details. |
| output_cluster_ids | if false fill segment_ids with segment-ids, and with cluster-ids otherwise (see fig__Cluster_vs_segment) |
| traits | traits class |
| ppmap | point property map. An overload is provided with get(boost::vertex_point,triangle_mesh) as default. |
- Returns
- number of segments if
output_cluster_ids is set to false and number_of_clusters otherwise
- Examples
- Surface_mesh_segmentation/extract_segmentation_into_mesh_example.cpp, Surface_mesh_segmentation/segmentation_from_sdf_values_example.cpp, Surface_mesh_segmentation/segmentation_from_sdf_values_SM_example.cpp, and Surface_mesh_segmentation/segmentation_with_facet_ids_example.cpp.
template<class TriangleMesh , class SegmentPropertyMap , class PointPropertyMap = typename boost::property_map<TriangleMesh, boost::vertex_point_t>::type, class GeomTraits = typename Kernel_traits<typename boost::property_traits<PointPropertyMap>::value_type>::Kernel>
| std::size_t CGAL::segmentation_via_sdf_values |
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const TriangleMesh & |
triangle_mesh, |
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SegmentPropertyMap |
segment_ids, |
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double |
cone_angle = 2.0 / 3.0 * CGAL_PI, |
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std::size_t |
number_of_rays = 25, |
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std::size_t |
number_of_clusters = 5, |
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double |
smoothing_lambda = 0.26, |
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bool |
output_cluster_ids = false, |
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PointPropertyMap |
ppmap = PointPropertyMap(), |
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GeomTraits |
traits = GeomTraits() |
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) |
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#include <CGAL/mesh_segmentation.h>
Function computing the segmentation of a surface mesh.
This function is equivalent to calling the functions CGAL::sdf_values() and CGAL::segmentation_from_sdf_values() with the same parameters.
- Note
- There is no direct relation between the parameter
number_of_clusters and the final number of segments after segmentation. However, setting a large number of clusters will result in a detailed segmentation of the mesh with a large number of segments.
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For computing segmentations of the mesh with different parameters (i.e. number of levels, and smoothing lambda), it is more efficient to first compute the SDF values using
CGAL::sdf_values() and use them in different calls to CGAL::segmentation_from_sdf_values().
- Precondition
is_triangle_mesh(triangle_mesh) -
number_of_clusters > 0
- Template Parameters
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| TriangleMesh | a model of FaceListGraph |
| SegmentPropertyMap | a ReadWritePropertyMap with boost::graph_traits<TriangleMesh>::face_descriptor as key and std::size_t as value type |
| GeomTraits | a model of SegmentationGeomTraits |
| PointPropertyMap | a ReadablePropertyMap with boost::graph_traits<TriangleMesh>::vertex_descriptor as key and GeomTraits::Point_3 as value type. |
- Parameters
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| triangle_mesh | surface mesh on which SDF values are computed |
| [out] | segment_ids | the segment or cluster id of each facet |
| cone_angle | opening angle in radians for the cone of each facet |
| number_of_rays | number of rays picked in the cone of each facet. In our experiments, we observe that increasing the number of rays beyond the default has a little effect on the quality of the segmentation result |
| number_of_clusters | number of clusters for the soft clustering |
| smoothing_lambda | factor which indicates the importance of the surface features for the energy minimization. It is recommended to choose a value in the interval [0,1]. See the section Hard clustering for more details. |
| output_cluster_ids | if false fill segment_ids with segment-ids, and with cluster-ids otherwise (see fig__Cluster_vs_segment) |
| traits | traits class |
| ppmap | point property map. An overload is provided with get(boost::vertex_point,triangle_mesh) as default. |
- Returns
- number of segments if
output_cluster_ids is set to false and number_of_clusters otherwise
- Examples
- Surface_mesh_segmentation/segmentation_via_sdf_values_example.cpp.
1.8.17