CGAL users discussion list

[ak4733 <>]

Hi all,

Disclaimer: I am new to CGAL. I've been working with CGAL for less than a
week, so apologies if this is a silly question.

I'm attempting to speed up my application utilizing alpha shapes. To my
understanding, Alpha_shapes_3 generates a family of alpha shapes across
different alphas. Fixed_alpha_shape_3 generates a single alpha shape for a
given alpha (I just need a single alpha shape). The documentation says that
this approach should be faster, but I'm finding that it takes just as long,
if not even longer, than Alpha_shapes_3 !!! I'm not too sure as to why this
is occurring; unfortunately it may be because of some type / kernel
mismatch, and I don't have enough understanding of CGAL to debug that
effectively given the limited examples on alpha shapes. I use the same point
models for both alpha generations. 

Here is my simplified setup:

typedef CGAL::Exact_predicates_inexact_constructions_kernel Gt;

typedef CGAL::Fixed_alpha_shape_vertex_base_3<Gt> Vb;
typedef CGAL::Fixed_alpha_shape_cell_base_3<Gt> Fb;
typedef CGAL::Triangulation_data_structure_3<Vb, Fb> Tds;
typedef CGAL::Delaunay_triangulation_3<Gt, Tds> Triangulation_3;
typedef CGAL::Fixed_alpha_shape_3<Triangulation_3> Alpha_shape_3;

typedef Gt::Point_3 Point;

std::list<Point> points; //I generate some points for this list in my code

Alpha_shape_3 as(points.begin(), points.end(), 1); //note I defined
alpha_shape_3 for fix_alpha

Any help / tips are appreciated!






--
Sent from: http://cgal-discuss.949826.n4.nabble.com/