[mapserver-users] Shapefile spatial index challenge

[Ben Madin]

G’day Lydon,

I feel your pain, but there is little benefit to creating more quadrants. The idea (as I understand it - could be wrong) is to be able to use a (fast) bounding box to find the polygons to test, rather than having to test against every polygon using more complex algorithms. 

I suppose you could consider that if you want to find out if a point is in one or more of your polygons, the benefit of having more index squares. You only have 8 polygons (I presume) so this should limit you in most cases to only having to compare your ‘point’ with only a couple of polygons using the more complex algorithms.

hth

cheers

Ben




> On 2015-10-08, at 21:31 , Lydon Chandra <lydon_chandra at technologyonecorp.com> wrote:
> 
> Hi List,
> 
> How can we generate more quadrants for the spatial index for the Australia polygon below ?
> 
> Using MapServer shptree, even forcing it to go to 50 level deep, the spatial index does not have more quadrants.
> 
> More data and details at:
> http://www.evernote.com/l/AhrYASBGtqVOkJn0BLqZkceADvOsA_UBfvY/ <http://www.evernote.com/l/AhrYASBGtqVOkJn0BLqZkceADvOsA_UBfvY/>
> 
> 
> <image.png>
> 
> 
> Kind Regards,
> Don
> 
> 
> 
> 
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Ben Madin

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