Shape Optimization

[Frank Warmerdam]

On 1/19/06, Luca Manganelli <luca76 at gmail.com> wrote:
> hi, which optimizations are available for shapefiles?
>
> I have one big shape of 17MB.

Luca,

I am correct that this is a 17MB shapefile with just a single
shape in it?   That's a big shape!

> I made:
>
> shptree bigshape.shp 8
>
> it created a new .qix file (but I should insert it anywhere in my map file?),
>
> but the performance is same as before...
>
> Is there any tool such   'gdaladoo'  for shapefiles?

I would suggest what you need is "feature generalization" to
produce a version of this feature with less vertices, suitable for
use at lower resolutions.  You might also consider whether it
would be appropriate to break your feature into tiles, though
whether this is practical depends on your use of the feature, and
how you want it rendered.

It is also quite possible that there are points in the shape reading
code, or the rendering code that are not really adapted
optimally to handling very large single features.  There may be
things that could be done to optimize the code, though I can't
think of any obvious issues off hand.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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