CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

What I mean is if you need both clusters and segments but want to save 
on computation time, you can run the segmentation algorithm to extract
segments and then clusters using `connected_components()` (instead of
another run of segmentation).

Sebastien.

On 05/22/2016 02:32 PM, Sukhraj Singh wrote:
> Thanks for your answer, Sebastien
> Do I really need to use connected_components()
>
> I already have the "segment_pmap", where the value is the segment id to
> which that particular face belongs.
> And one could parse the Polyhedron and collect all the faces having
> particular segment ID.(Of-course I need to check, how to implement the same)
> Is my understanding correct ?
>
>
>
> Further, quoting from my previous email:
>
>     Two spatially apart areas( i.e. not having
>     common edges) of a Mesh may fall into same segment, since they had
>     comparable SDF values.
>
>
> I am not sure about it, they of-course may fall into same cluster, but
> may not be to the same segment.  In such a case if, faces that don't
> share edge, will fall into different segment always, even though they
> were in same cluster, using connected_components() may not be required ?
>
>
>
>
> On Thu, May 12, 2016 at 6:00 PM, Sebastien Loriot (GeometryFactory)
> <
>  
> <mailto:>>
>  wrote:
>
>     On 05/12/2016 02:16 PM, Sukhraj Singh wrote:
>
>         Salut,
>
>         The "Triangulated Surface Mesh Segmentation" module allows one to
>         segment a surface mesh using the SDF values.
>         It creates a Property Map which is colorized according to the
>         indices,
>         resulting into segments. Two spatially apart areas( i.e. not having
>         common edges) of a Mesh may fall into same segment, since they had
>         comparable SDF values.
>
>         My question is, how can one extract these segments. Since I want
>         to do
>         further processing on a segment separately. Also I would like
>         further
>         divide a segment, into say sub-segments , where a sub-segment
>         will have
>         faces which are not spatially apart, i.e.  a subset which is having
>         common edges only.
>
>
>
>     Set the parameter output_cluster_ids to true when calling the
>     segmentation function
>
>     
> http://doc.cgal.org/latest/Surface_mesh_segmentation/group__PkgSurfaceSegmentation.html#ga8533ea7b1062ebbabe3bf23fed303f24
>
>     If you need also the segments, then set the option to false and
>     use the function connected_components() considering as constrained
>     edges the edges between two faces belonging to different
>     segments.
>
>     
> http://doc.cgal.org/latest/Polygon_mesh_processing/group__keep__connected__components__grp.html#gabe2052b2281e1e628e68d8fea94be2d9
>
>
>     Sebastien.
>
>
>
>         Thanks to inform.
>
>
>
>
>         P.S. I am a newbie.
>         --
>         Sukhraj Singh
>
>
>
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>
>
>
> --
> Sukhraj Singh