[mapguide-users] Newbie learning to insert images

[Frank Warmerdam]

Krunoslav wrote:
> I have a folder of 50 high quality georeferenced TIFF images, and I would
> like to make a map with those images. Each image has about 100MB. I'm using
> OSGeo FDO Provider for raster in Mapguide Studio
> 
> So when I make new data connection, enter Default Raster File location, and
> add 10 images, Studio communicates with site for about 20 minutes and
> finally connection fails. I guess tiff images are too large.
> 
> Other thing I tried to do is convert images to jpeg. But, how do I convert
> georeferencing .tfw files for those images? I tried to rename them to .jwg ,
> but doesn't work. So, can FDO provider for raster handle jpeg images? What
> format of georeferencing file does it expect?
> 
> Anyway, my question would be: which is the easiest way to publish raster
> images? 

Krunoslav,

First, can you be more specific about what version of the OSGeo raster
provider you are using?  There are some important fixes at:

   http://www.gdal.org/dl/mapguide

Second, have you tried it with a single image first?

Third, to extract an image for mapping purposes from a TIFF file it is
pretty important to organize the image in an appropriate manner.  In
particular for optimum performance you should convert the image to tiled
format, and build overviews.  This can be accomplished with the following
GDAL commandline commands.  The GDAL utilities are available as part of
FWTools (http://fwtools.maptools.org).

  gdal_translate -co TILED=YES in.tif out.tif
  gdaladdo out.tif 2 4 8 16 32 64 128

Once you are comfortable with the performance using one image, you can
try scaling up to more images.  If you add each image as a seperate
datasource and layer I think the overhead will be substantially higher
than if you just put all the images you want to serve in a single directory
and add that directory as the raster location.  Make sure the images you
want to serve are the only thing in that directory.

As things currently stand the GDAL based OSGeo raster provider does not
include any optimizations to keep track of the set of files in a
directory.  So each map draw request is likely to result in all the images
being opened and the summary information scanned.  This will be fairly
expensive for 50 images, and will degrade performance substantially.

There is some work likely to happen soon to help address this.  In the meantime
it might actually be better for you to merge your 50 images into a smaller
number of larger images.  For instance if you merged these into four TIFF
files of around 1.2GB each that would be quite helpful.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org