[gdal-dev] GDAL Speed Optimization

[Stefano Moratto]

Frank,
        I have increased the cache as you suggested using GDALSetCacheMax
and it produced a performance gain. Thanks.

I think I can improve more acting on the virtual datataset that I use to
adapt the image to the paper size.
I have to look into the tms driver in order to understand how it download
the tiles to compose the final image.

Stefano

On Fri, Jun 11, 2010 at 6:17 PM, Frank Warmerdam <warmerdam at pobox.com>wrote:

> Stefano Moratto wrote:
>
>> Frank,
>>        The source images are  a sequence of tiles from openstreetmaps.
>> Every tiles has a fixed size (256 x 256) and the area they covers depends
>> from the zoom level.
>> It is explained very well in
>> http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection.
>>
>> I use interpolation (via a virtual dataset)  because my window size and
>> the paper size are not a multiple of 256 x 256.
>> I use reprojection because I've to mix this raster datasource with a
>> vector datasource that has a different projection. Reprojecting my vector
>> data to openstreet projection do not affect the performance.
>>
>> So I think the key factor is the resizing ( I use "bilinear"
>> interpolation) and the size of the bitmap that may cause paging.
>>
> ...
>
>  Can you suggest some other parameters?
>>
>
> Stefano,
>
> Sorry, I wasn't able to learn much more skimming the code and
> referenced web page.  Have you tried the cache size setting
> I suggested?
>
>
> Best regards,
>
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam<http://pobox.com/%7Ewarmerdam>
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>
>


-- 
Dr.Eng. Stefano Moratto
stefano.moratto at gmail.com
stefano.moratto at csiat.it
http://www.csiat.it - Traffic Optimization Software
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