[mapguide-users] MrSID files through GDAL FDO provider

[Jonathon McIntyre]

BTW, I tried the gdal_translate to test how the images work as ecw
however, they end up being larger than the 500MB limit set by the free
ECW sdk so they won't translate.  The FWTools is a very cool utility
though.  Frank has done a great job with it.

Jonathon

 

From: mapguide-users-bounces at lists.osgeo.org
[mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of Andy
Morsell
Sent: Wednesday, June 13, 2007 11:20 PM
To: 'MapGuide Users Mail List'
Subject: RE: [mapguide-users] MrSID files through GDAL FDO provider

 

Hi Jonathon,

All of my answers refer to 1.2 RC1.

 

Yes, the GDAL provider does try to hit all of the images in the feature
source when the map is first accessed regardless of whether that layer
is actually visible.  This issue has been entered by me into Trac
already.  

 

I have seen the ECW and MrSID providers trying to access the same image
files as well.  Doesn't make sense to me either.

 

I am currently running a client site with 10 GB of ECW imagery, each
about 25 MB and seeing relatively good performance (except for the first
issue above).  So, perhaps your issue is more confined to the MrSID
format?  In my case, the data started as JPEG2000 format which the GDAL
provider could not successfully read so I used fwtools gdal_translate to
convert all of them to ECW.  Perhaps translating your MrSID's to ECW's
would help in this case?  Also, Jason Birch and others are working on
image tile index support for directories of images which could help with
your particular problem.

 

By the way, here are some of the GDAL issues I have logged with the 1.2
beta that might be of interest:

 

http://trac.osgeo.org/mapguide/ticket/191

http://trac.osgeo.org/mapguide/ticket/187

http://trac.osgeo.org/mapguide/ticket/160

 

 

Andy Morsell, P.E. 
Spatial Integrators, Inc. 
http://www.SpatialGIS.com 

________________________________

From: mapguide-users-bounces at lists.osgeo.org
[mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of Jonathon
McIntyre
Sent: Wednesday, June 13, 2007 12:21 PM
To: mapguide-users at lists.osgeo.org
Subject: [mapguide-users] MrSID files through GDAL FDO provider

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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