[vtkusers] KDTree timing demo

[Andy Bauer]

Now I'm not sure why you're not getting the search times to decrease.  At
this point I think you'd have to profile the code to see where the time is
being spent.

On Wed, Sep 29, 2010 at 1:22 PM, David Doria <daviddoria at gmail.com> wrote:

> On Wed, Sep 29, 2010 at 1:08 PM, Andy Bauer <andy.bauer at kitware.com>wrote:
>
>> I broke up the times between kdtree build time and search time and the
>> search time dominates the build time.
>>
>> I'm guessing that the problem is that the grid isn't suited for the kd
>> tree point locator.  This happens when the points have some "uneven"
>> clustering that results in the geometry of the bins in the kd tree to have
>> large aspect ratios (1 or 2 direction lengths dominates the others).  If you
>> try an image data/uniform grid with the cells having equal lengths on each
>> side you should see the timing drop down as the number of kd tree levels is
>> increased.
>>
>> Andy
>>
>
> I replaced the vtkSphereSource with a:
>
>   vtkSmartPointer<vtkPointSource> reader =
>     vtkSmartPointer<vtkPointSource>::New();
>   reader->SetNumberOfPoints(10000);
>   reader->SetRadius(5);
>   reader->Update();
>
> The run time is still pretty much flat across this SetMaxLevel parameter.
>
> David
>
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