CGAL users discussion list

[Wonwoo Lee <>]

> Your implementation must have been terribly slow.

Yes, mine is very slow if the number of views increases and the shape  
of the silhouette becomes complicated.
It may not be my intention to use filtering, because I'm not much  
familiar with the kernel things.
When I wrote the code, I referred your visual hull example and demo  
codes.

Here is the question.
If I want to compute the exact visual hull from silhouettes,
How do I have to change my headers and kernels from the current code,
while preserving the compatibility with CGAL 3.3 ?

And, which header file employs the use of MP_Float ?


On Aug 27, 2007, at 5:29 PM, Peter Hachenberger wrote:

> Hi,
>
> I'm a bit surprised that you used filtering with Nef_3 in CGAL 3.2.1,
> because filtering was not supported for Nef_3 in that CGAL version.  
> Your
> implementation must have been terribly slow.
>
> The problem with your program is, that Nef_3 does not work with
> MP_Float, since it does not support divisions. You must have installed
> CGAL 3.3 without GMP. If you add GMP support, the Exact_..._kernel  
> uses
> Gmpq instead of MP_Float and the compilation works.
>
> Peter
>
> On Mon, 2007-08-27 at 14:11 +0900, Wonwoo Lee wrote:
> > Hi, CGAL developers and users.
> >
> > I wrote a class which uses Nef_3 boolean operation for the
> > exact visual hull reconstruction from silhouette images.
> > My code had no errors with the CGAL 3.2.1, when I built it.
> >
> > However, it causes many compile errors with the file  
> > 'lazy_exact_nt.h'
> > when I try to compile my code
> > after I updated the CGAL to version 3.3.
> >
> > The errors are about the definition of the operator '/', such as :
> >
> > c:\program files\cgal-3.3\include\cgal\lazy_exact_nt.h(325) : error
> > C2784: 'CGAL::Root_of_2<RT_> CGAL::operator /(const
> > CGAL::Root_of_2<RT_> &,const CGAL::Root_of_2<RT_> &)' : could not
> > deduce template argument for 'const CGAL::Root_of_2<RT_> &' from
> > 'CGAL::MP_Float'
> >
> > 1>c:\program files\cgal-3.3\include\cgal\lazy_exact_nt.h(325) : error
> > C2784: 'CGAL::Interval_nt<Protected> CGAL::operator /(double,const
> > CGAL::Interval_nt<Protected> &)' : could not deduce template argument
> > for 'const CGAL::Interval_nt<Protected> &' from 'CGAL::MP_Float'
> >
> > Actually, I'm not much familar with the way CGAL works.
> > I referred the demos and examples to develop my code.
> > Anyone can help me ?
> >
> >
> >
> > For more information, I listed header files I'm using.
> >
> > #include <CGAL/Homogeneous.h>
> > #include <CGAL/Nef_polyhedron_3.h>
> > #include <CGAL/IO/Nef_polyhedron_iostream_3.h>
> > // Headers for Polydedron_3
> > #include <CGAL/Polyhedron_3.h>
> > #include <CGAL/IO/Polyhedron_iostream.h>
> > #include <CGAL/Polyhedron_incremental_builder_3.h>
> >
> > #include <CGAL/Exact_predicates_exact_constructions_kernel.h>
> >
> > // typedefs....
> > typedef CGAL::Exact_predicates_exact_constructions_kernel Kernel;
> >
> > typedef CGAL::Nef_polyhedron_3<Kernel>  Nef_polyhedron_3;
> >
> > typedef CGAL::Polyhedron_3<Kernel> Polyhedron_3;
> > typedef Polyhedron_3::HalfedgeDS HalfedgeDS;
> > typedef Kernel::Point_3  Point_3;
> > typedef Kernel::Vector_3 Vector_3 ;
> > typedef Kernel::Plane_3  Plane_3;
> > typedef Kernel::Line_3  Line_3 ;
> >
> > typedef Nef_polyhedron_3::Aff_transformation_3   
> > Aff_transformation_3 ;
> --
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