CGAL users discussion list

[Matthijs Sypkens Smit <>]

On Wednesday 15 August 2007 11:09, Kuan wrote:

> I write it not so precise. Just some points, and build a
> delaunay_triangulation_3, in some algorithm i have to find out whether a
> point is in convex hull (crust algorithm).

I'm sorry, but your problem is not very clear to me.

CGAL by itself has the capability to do exact computations of 
inside/outside tests for convex hulls. If you are experiencing problems 
with the results while requiring only 5 decimals of precision in your 
final answer, then you are most likely doing something fundamentally 
wrong.

If you cannot explain in more detail how your problem arises, I'm afraid I 
cannot help you any further.


> 2007/8/15, Matthijs Sypkens Smit 
> <>:
> > On Wednesday 15 August 2007 02:13, Kuan wrote:
> > > Hi all,
> > > Now i have a precision problem.
> > > I am using delaunay_triangulation_3 to find out whether a point is
> > > in convex hull.
> > > But because the problem of precision, i usually get a wrong answer.
> > > For example i generate some points on a cylinder by code, and write
> > > it into a file and read it out.
> >
> > Did you make sure to write the points out with maximal precision?
> >
> > > And then many of the points is defined as not in convex
> > > hull.(because the number is not so precision, you can image that?).
> >
> > The points are not in the convex hull of what? A cyclinder-surface
> > represented by triangles?
> >
> >
> > --
> > Matthijs Sypkens Smit
> > --
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-- 
Matthijs Sypkens Smit