CGAL users discussion list

[Michael Jeulin-L <>]

Laurent Saboret wrote:
> Michael Jeulin-L wrote:
> > Laurent Saboret wrote:
> > > Michael Jeulin-L wrote:
> > > > Laurent Saboret wrote:
> > > > > Hi Michael,
> > > > >
> > > > > The assertion below might occur when the Poisson reconstruction 
> > > > > parameters are out of the recommended range.
> > > > > See "Contouring parameters" paragraph at 
> > > > > http://www.cgal.org/Manual/3.5/doc_html/cgal_manual/Surface_reconstruction_points_3/Chapter_main.html#Subsection_45.6.1 
> > > > >
> > > > >
> > > > > You may reconstruct your objects with various parameters with the 
> > > > > examples provided with CGAL:
> > > > > - poisson_reconstruction in 
> > > > > examples/Surface_reconstruction_points_3 (command line)
> > > > > - Point_set_demo in demo/Surface_reconstruction_points_3 (Qt GUI)
> > > > > I recommend you to try first with the default parameters, then 
> > > > > with the parameters you used in your code.
> > > > >
> > > > > Best regards,
> > > > > Laurent Saboret
> > > > >
> > > > >
> > > > > Michael Jeulin-L wrote:
> > > > > > Hello everybody,
> > > > > >
> > > > > > Excuse me to disturb, but I have a problem with Poisson function 
> > > > > > and I cannot
> > > > > > find the solution to fix the problem.
> > > > > >
> > > > > > From this example :
> > > > > > http://www.cgal.org/Manual/3.5/doc_html/cgal_manual/Surface_reconstruction_points_3/Chapter_main.html 
> > > > > >
> > > > > >
> > > > > > I try to compute several object with a loop, for some of them all 
> > > > > > is working
> > > > > > fine and I have the output I expect. However, for others my 
> > > > > > application crash
> > > > > > with the following error :
> > > > > >
> > > > > > CGAL error: precondition violation!
> > > > > > Expression : tester(d)
> > > > > > File : CGAL/Triangulation_3.h
> > > > > > Line: 643
> > > > > > Explanation:
> > > > > > Refer to the bug-reporting instructions at 
> > > > > > http://www.cgal.org/bug_report.html
> > > > > >
> > > > > > when I try to compute, I think : 
> > > > > > "function.compute_implicit_function()"
> > > > > > When I look in the file triangularization_3.h, it seems to be 
> > > > > > caused by a
> > > > > > conflict with cell. How could I resolved the problem before my 
> > > > > > application bug
> > > > > > ?
> > > > > >
> > > > > > Thank you very much for every answer.
> > > > >   
> > > > Thank you very much.
> > > >
> > > > But I mean, I try to compute the surface for very different kind of 
> > > > objects.
> > > > So, is there a way to know before computing until the crash if the 
> > > > conditions are matched or not.
> > > > It`s the same problem for the normals computations.
> > > >
> > > > No way to make a preprocessing in order to detect wrong objects ?
> > > >
> > > > Actually I don`t think so, but still ask the question just in case.
> > > >
> > > > Thank.
> > > > Kind Regards.
> > > Hi Michael,
> > >
> > > The examples provided with CGAL (see above and also 
> > > examples/Point_set_processing_3 for normals computation) compute 
> > > appropriate parameters for any input object.
> > >
> > > Best regards,
> > > Laurent Saboret
> > Hi,
> >
> > Indeed, It is the case for normals computation but not for 
> > polyhedrons one.
> > So, I still have the problem to prevent/avoid the assertions when the 
> > Poisson reconstruction parameters are out of the recommended range.
> >
> > Is there any way to do that or should I change directly CGAL source 
> > code ?
> >
> > Thank you very much.
> > Best Regards.
> Hi Michael,
>
> I am not sure that I understand your question. The examples above 
> compute appropriate parameters for the reconstruction function 
> make_surface_mesh(). This should be enough to reconstruct your data.
> Am I missing something?
>
> Best regards,
> Laurent Saboret
>
>
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Hi,
The problem is that`s not. Cause when I compute the parameters I have in 
some cases assertion error.
It could be to compute average_spacing, bounding_sphere... and if I have 
understand well Poisson Construction (

// Defines the implicit surface: requires defining a
        // conservative bounding sphere centered at inner point.

), I need this parameters to compute the implicit surface.

So, in function of my options :

// Poisson options
   FT sm_angle = 20.0; // Min 
<http://www.cgal.org/Manual/last/doc_html/cgal_manual/NumberTypeSupport_ref/FunctionObjectClass_Min.html#Cross_link_anchor_105>
 triangle angle 
<http://www.cgal.org/Manual/last/doc_html/cgal_manual/Kernel_23_ref/Function_angle.html#Cross_link_anchor_343>
 in degrees.
   FT sm_radius = 30; // Max 
<http://www.cgal.org/Manual/last/doc_html/cgal_manual/NumberTypeSupport_ref/FunctionObjectClass_Max.html#Cross_link_anchor_104>
 triangle size w.r.t. point set average spacing.
   FT sm_distance = 0.375; // Surface Approximation error w.r.t. point set 
average spacing.

+

 FT average_spacing = CGAL::compute_average_spacing 
<http://www.cgal.org/Manual/last/doc_html/cgal_manual/Point_set_processing_3_ref/Function_compute_average_spacing.html#Cross_link_anchor_1517>(points.begin(),
 points.end(),
                                                      6 /* knn = 1 ring */);

My autommatic reconstruction works better or worse but still bug at a moment.
I just try to be able to prevents this bug cause by out of range parameters 
for Poisson Reconstruction.


Thank you to interest to my problem.
Kind Regards.

--
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Michael Jeulin-L, ComputaMaps

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