CGAL users discussion list

[Pierre Alliez <>]

dear Leon,

thank you for discussing this bug.
I think the problem comes from the eigenvalue computation.

we will dig this out.

in the meantime I invite you to replace the code which computes the
eigenvalues/vectors by
calls to the eigen library, and report whay you get here in this list.

thank you,

Pierre



Le 21/09/2011 08:13, Leon Nan a écrit :
> Hi all,
>
> I am using CGAL::linear_least_squares_fitting_3() to fit planes from point 
> set. It works pretty well for data set with more than 3 points. But I was 
> surprised that this function behaved when fitting a plane form 3 points. 
> The function returned 0.495031, which meant the variance orthogonally to 
> the fitting plane was quite big. Acutally 1.0 is expected because 3 points 
> are exactlly in the same plane. Can someone explain?
>
> Here is the code I call the fitting function:
>                 Plane3f plane;
>               double q = CGAL::linear_least_squares_fitting_3(
>                       pts.begin(), 
>                       pts.end(), 
>                       plane,
>                       CGAL::Dimension_tag<0>()
>                       );
>
>
> And the input(only 3 points):
>       ==================================
>               86.1817 3075.31 1031.53
>               164.575 3075.31 913.936
>               754.546 0 28.9401
>       ==================================
>
> --
> Leon
> http://web.siat.ac.cn/~liangliang/
>
>