[Mapserver-users] Projection AUTO, GDAL and ECW files

[Brent Fraser]

Frank,

  I see where I can implement your suggestion in mapraster.c.  From the
implementor's perspective the enhancement would pertain to raster files used
in a TILEINDEX layer:

    - no additional map file keywords needed (I wasn't looking
        forward to adding TILEINDEXPROJECTION!)
    - defaults to current behavior: if the tileindex shapefile
         is in the same coord sys as the data, state the coord
         sys using PROJECTION in the layer definition

    - if TILEINDEX is in a different coord sys, then simply

    1.  add .prj file for the shapefile and .prj files for the
         datafiles (if they do not already hold coord sys
         definition info).
    2. add PROJECTION AUTO to layer definition.

That should take my 20 layers down to one layer, and not break Ed's
scripting.

Thanks!
Brent

----- Original Message -----
From: "Frank Warmerdam" <warmerdam at pobox.com>
To: "Brent Fraser" <bfraser at geoanalytic.com>
Cc: "mapserver-users" <mapserver-users at lists.gis.umn.edu>
Sent: Monday, May 12, 2003 2:41 PM
Subject: Re: [Mapserver-users] Projection AUTO, GDAL and ECW files


> Brent Fraser wrote:
> > Frank (and others),
> >
> >   I'm doing some investigation into making the TILEINDEX feature a
> > little more flexible with respect to coordinate systems.  I like the
> > PROJECTION AUTO feature added to MapServer 3.7 for datastores, but not
> > all of them store coordinate system information with the data (e.g.
> > shapefiles, jpg), and some of them have their own "proprietary" method
> > of specifying it (e.g. ECW) not handled by GDAL.  This means that
> > integrating new datasets requires Mapserver implementors to carefully
> > define the coordinate system in each map file.
> >
> >   What do you think about having GDAL read an additional file that
> > specifies the coordinate system definition for a specific data file?
> > The file could/should have the same filename prefix as the datafile with
> > an extension of prj, csd or something that hasn't been used for similar
> > things.  The format could be PROJ strings (or EPSG numbers, or OGIS WKT
> > format).
>
> Brent,
>
> I think it would be reasonable for GDAL drivers for formats that no
> inherent coordinate system support to allow using .prj files.  However,
> in the case of the ECW driver the real solution is to fix the damn thing.
>
> However, I am in no immediate danger of implementing such a .prj file
> fallback feature for all the coordinate-system-less drivers at this time.
> We could however conceivable implement the same thing within MapServer
> much like the .wld file fallback code is/was working in mapserver.
> Basically, if GDALGetProjectionRef() doesn't return something helpful,
just
> check for a .prj file and use that if present.
>
> Best regards,
>
> --
> ---------------------------------------+----------------------------------
----
> 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    | Geospatial Programmer for Rent
>
>
> _______________________________________________
> Mapserver-users mailing list
> Mapserver-users at lists.gis.umn.edu
> http://lists.gis.umn.edu/mailman/listinfo/mapserver-users