[Gdal-dev] Re: MrSID on MapServer w/ FWTools 0.9.9

[Frank Warmerdam]

On 8/17/05, Richard Greenwood <richard.greenwood at gmail.com> wrote:
> On windows, it seems that when GDAL_DRIVER_PATH is set as an
> environment variable, mapserver is not reading it, but when set in the
> map file with:
>    CONFIG GDAL_DRIVER_PATH "F:\FWTools0.9.9\gdal_plugins"
> thing work. I have tested this on Wondows 2000 and XP, with several
> variations of quoted/non-quoted, forwardSlash/backSlash,
> driveLetter/noDriveLetter. Gdalinfo see the environment variable,
> mapserver does not.

Rich,

I'm not too sure why the environment variable didn't work.  Did you
set it as a system env. variable or user env. variable?  

> I must admit that the distinction between 'gdal_plugins' and 'plugins'
>  had me chasing my tail for a bit.
> 
> Unfortunatley, now that mapserver/gdal is processing my sid file, I
> get the following error after a few seconds:
> msDrawMap(): Image handling error. Failed to draw layer named 'color2004'.
> MrSIDRasterBand::IRasterIO(): Failed to load image. mg2 somethi:
> Unable to access file. GDALRasterIO() failed: drawGDAL()

The above message seems to mean that a poImageReader->read()
call failed.   It looks like the low level MrSID error message has
been truncated for some reason, perhaps by an error message length
limit in MapServer.  So it literally says "mg2 somethi"?  Funky.

I will try some experiments here to see if I can reproduce this 
behavior.  Would you mind filing a bug in bugzilla for this issue 
with the error message, and the gdalinfo report of the mrsid file
in question?  Also, could you note the extents (and render size)
of the mapserver request that lead to this problem?  I am suspecting
we may be trying to read one-too-many overview levels, since this
is an area that has changed in recent months.  
 
> Getting this file to display in mapserver is not a big deal for me, so
> please don't put undue effort into addressing my problem. I am trying
> to help a small rural county access some federally produced imagery.
> I'd prefer not to use MrSID, but I have had mrsiddecode decoding this
> file for 5.5 days now, and it's only 40% of the way thru it.

Well, I have a number of paid clients using MrSID support, so I am
keen to work out any bugs or quirks in the implementation. 

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