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Re: [cgal-discuss] Nearest neighbor query time increases as epsilon increases?!


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  • From: "Sebastien Loriot (GeometryFactory)" <>
  • To:
  • Subject: Re: [cgal-discuss] Nearest neighbor query time increases as epsilon increases?!
  • Date: Mon, 02 Dec 2013 09:59:25 +0100
  • Organization: GeometryFactory

Could you provide a minimal example showing the issue?

Sebastien.

On 12/01/2013 11:29 PM, Samaras wrote:
To make matters worse, here is another behavior with the same distance class
as mentioned above, that I don't understand.

Now I have a dataset in 22 dimensions with 110K number of points. Then I
produce 1000 random query points in the cube [-1000, 1000]^D (have tried
with 1 and 2, instead of 1000, but the behavior seems to be the same).

If I use the splitting rule Midpoint_of_max_spread for the kd_tree, the tree
is smaller. The strange fact is that now the time measurements seem to be
pretty much the same, regardless epsilon. With the default rule (i.e.
Sliding_midpoint), we have (roughly) the behavior mentioned in the previous
post.

default
Number of nodes: 69441
Tree depth: 53
NN 0.061071443 0.065089808 0.065244869
0.066301312
FN 0.057983228 0.051108550 0.047526043
0.042351644

Midpoint_of_max_spread
Number of nodes: 59123
Tree depth: 37
NN 0.057491852 0.058924140 0.059315090
0.058354231
FN 0.058201980 0.056180041 0.056738955
0.058448647

Two questions, that I can not answer myself and I am afraid no one from here
is able to do it too! :/



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