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/ -- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://sympa.inria.fr/sympa/info/cgal-discuss |
Could you share your benchmark?
I've just gave it a try with a bench program [1] with 351750 weighted points and I got: Building regular triangulation: 2.03785 Build Fixed weighted alpha complex Fixed 4.41835 Build family weighted alpha complex Family 13.0819 Build family filtered weighted alpha complex Family filtered 25.4051 Building exact regular triangulation: 4.34791 Build exact family weighted alpha complex Family exact 23.192 so ~4s vs 13s. Sebastien. [1] https://github.com/CGAL/cgal/blob/master/Alpha_shapes_3/test/Alpha_shapes_3/bench_walpha.cpp On 06/19/2018 05:26 PM, ak4733 wrote: > 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/ > -- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://sympa.inria.fr/sympa/info/cgal-discuss |
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