[mapguide-users] MrSID files through GDAL FDO provider

Jonathon McIntyre jm at pat.ca
Wed Jun 13 15:20:40 EDT 2007


Good morning,

I am working with MGOS 1.2 RC1 and the latest GDAL FDO providers on XP
Pro.

 

I have a directory with twenty five 40MB MrSID files in it.  If I create
a single data source against that directory, I have a limited
possibility that the images will actually process although there does
not seem to be any errors when I run MGServer from the command line. It
appears that the datasource is processed whether or not the layer is
turned on.

 

As an aside,  I did notice that if I have the ECW dll in the directory,
the messages indicate that it is trying to read the .sid format files as
ECW which adds to the time.

 

In order to test things out, I created a data source for each file.  I
noticed that for a couple of files, the processor usage spikes to 100%
but the images are displayed quickly.  As I add more files, the
processor spikes become longer and the delays far more apparent.  When I
get all 25 added my processor spikes to 100% usage for several minutes
although the images will eventually display.  Watching the mgserver from
the command line shows that the images process and some go very quickly
but others seem to be very slow (which may just be the result of the
processor being pegged).

 

I tried using fwtools to mosaic these images together but can only get
about 4 together before I hit the 4GB tiff limit.

 

I am trying to create a new single mosaiced .sid file to see if that
will make a difference but was wondering if there were any other ideas
of what I could do to improve the performance of the display of the
images?

 

Thanks,

J

 

 

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