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Re: [cgal-discuss] Fast search of local positive quadruples on the sphere


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  • From: Илья Палачев <>
  • To: "" <>
  • Subject: Re: [cgal-discuss] Fast search of local positive quadruples on the sphere
  • Date: Wed, 18 Feb 2015 20:48:39 +0300
  • Envelope-from:

18.02.2015, 20:17, "Olivier Devillers" <>:

Are you sure ?

If you search for empty triangles for uniform distribution you have clearly Omega(n^2)
(any segment can be completed in an empty triangle.
I would guess something like n^2 log n for the correct result.

I also would expect something similar for triangles containing one point.
 
 
In this article http://ssg.mit.edu/~willsky/publ_pdfs/133_pub_MIV.pdf
authors published the following graph:
 
It shows that in their case there was 3000 local tests for 600 directions.
Maybe I'm misunderstanding their definition of "local positive cone tests":
 
DEFINITION 1 (LOCAL FAMILY) Given a set S of m distinct unit vectors in R^n and a member from this set u_k, we define the local family corresponding to u_k to be the set of all distinct (n + 1)-tuples of vectors from S such that u_k is one element of the (n + 1)-tuple and the remaining n vectors of the ( n + 1)-tuple contain only themselves and uk from S in their full positive cone.
 
What do you think about that?
 
 

PNG image




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