MrSID is not displaying

[Frank Warmerdam]

On Tue, 22 Feb 2005 15:46:48 -0600, Yar Doroshenko <numerous at gmail.com> wrote:
> Hi guys, I need some help,
>
> I'm using Mapserver 4.2 and GDAL 1.2.5 (on Windows XP)
> I have compiled GDAL with DSDK for MrSID support.
>
> In my map file I defined a a layer
>
> LAYER
> NAME "14_1_1.sid"
> data "mrsid/14_1_1.sid"
> status default
> type raster
> #processing "bands=1, 2, 3"
> END
>
> Is this a correct MrSID raster definition?

Yar,

This looks fine.   I would suggest you review the extents you
are using for your map and the extents that gdalinfo reports
for the .sid file.

Also, you should seriously consider upgrading to a nightly
snapshot of GDAL.  I made changes in the MrSID driver
in GDAL that can dramatically improve performance with large
files.

> I'm not getting any errors, but my MrSID does not display. Now, I did
> not configure mapserver for GDAL. I've heard that I need to either
> recompile or reconfigure the Mapserver once I add MrSID support to
> GDAL. How do I do that?

I don't know what build of mapserver you are using, nor how you
are trying to replace the GDAL it is built with, so that question is
hard to answer.

Generally, if you have a MapServer build you have downloaded
from somewhere else, and then you try to substitute a new GDAL
build into that you are likely to run into serious problems.  If you
want to build your own GDAL you should likely build your own
mapserver as well.  That can be a challenging task.

For what it is worth (perhaps not much to you right now), I hope
to start releasing a MrSID driver "plugin" for FWTools releases in
the not to distant future.

If you have the disk space you might be best off just converting
your MrSID file(s) into GeoTIFF.  You should get comparible
or better display performance though of course disk space may
be an issue.  Try something like:

 gdal_translate -co TILED=YES your.sid your.tif
 gdaladdo your.tif 2 4 8 16 32 64

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent