[mapguide-users] Newbie learning to insert images

[Frank Warmerdam]

Krunoslav wrote:
> Thank you very much for your help. I downloaded latest fixes from gdal.org. 
> 
> Now it works with single TIFF image. It is right where it should be, but it
> takes pretty long time to load. Now I'll try "gdaladdo" and report back what
> happens.
> 
> My obvious mistake was that I thought (as former web designer) that it is
> better to have a lot of smaller files than one big file. Is there any
> "optimum" size for Tiff image or can I merge them all together or it depends
> on my hardware?

Krunoslav,

It can be better to use many small files but it depends on the nature of
the software and what the typical map view is like.  Unfortunately, the
raster provider has no support for a tileindex mechanism to rapidly
select only the desired rasters for the current view, so many small files
are actually worse for now.  This is the part we hope to correct for a
future version.

GeoTIFF only supports up to 4GB file size, so that is the upper limit.
Until some sort of tileindexing is in place, it will generally be better
to merge files assuming they are contiguous and all at the same resolution.

> One more question for Mapguide Studio users: when I enter DefaultRasterFile
> location, is it really necessary to add files via "New" button, or this Data
> Connection will always look for images in DefaultRasterFile location?

I do not believe the files added with the New button have any effect.
If the DefaultRasterFileLocation property is the only thing that has any
effect currently.  If it points to a single file, then that file is the only
thing used.  If it points to a directory, then all the GDAL recognised raster
files in that directory will be scanned.

So if DefaultRasterFileLocation is currently pointing to the directory with
all the images, then all the images are already being scanned.

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