SPAM-LOW: RE: [mapguide-users] Problem with OS Geo FDO Provider for Raster.

[Frank Warmerdam]

Andy Morsell wrote:
> The link to the Autodesk whitepaper only pertains to the Autodesk raster
> provider.  The GDAL provider, in essence, works that way by default.   
> 
> I have a feeling with 50,000 images approaching a Terabyte, that MapGuide
> and the GDAL provider simply won't handle this well for dynamically serving
> the data.  You should strongly consider pre-processing your data into
> formats more suitable for this type of an application.  This would include
> mosaicing your data into county-wide wavelet compressed images.  I
> personally would recommend using ECW format, although MrSID would also work
> well.  By doing this, you eliminate the software having to open and process
> possibly thousands of images per map request.  As the user zooms in further,
> you might be able to switch to a layer that does display these higher
> resolution images, however.  My understanding is that the GDAL provider
> currently does not handle the indexing of many images in a directory well,
> so you may find this is not optimal at the moment.

Jeff,

I'd add that I think the GDAL provider *could* be suitable for this
size image if we get to incorporating a tileindexing scheme.  In the
meantime Andy has good advice.  Alternatively, you could build one really
large uncompressed Erdas Imagine format file with overviews.  This should,
in theory, also be fast to display from.  Of course, building a 1TB
mosaic may be a bit of an effort, and I an see how you would be annoyed
if after doing so it didn't actually have very good performance.

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