[mapserver-users] [gdal-dev] Gdaltindex with -t_srs and Mapserver

[Rahkonen Jukka]

Hi,

This is an intentional cross-posting and the main message is to support implementing RFC 37
http://mapserver.org/development/rfc/ms-rfc-37.html
and enlarge it to support mixed-projection raster tileindex layers, if possible.

-Jukka Rahkonen-

Vastaanottaja: 'gdal-dev at lists.osgeo.org'
Aihe: Re: [gdal-dev] Gdaltindex with -t_srs and Mapserver

Hi,

I did not meant to underestimate this little but extremely useful improvement. However, you made me hungry: if you can see so simply the image footprints, why not also the images?  I am already publishing in our WMS also the tileindex  shapefiles so people can see the image boundaries and make GetFeatureInfo queries from the image metadata that we have added to the shapefile as a few extra fields. In order to make it works we have reprojected images from their original projection zones into one common zone.  Now I wonder if it could be possible to make Mapserver to support tileindex layers containing source images with mixed projections. As a non-programmer I have a strong belief that if I can say what I want, someone can program it.

I believe that Mapserver already gets the correct image list from the mixed-projection shapefile.   I guess also that Mapserver does not read image metadata from the geotiff image files for getting the projection but it relies on the LAYER level PROJECTION setting. In my simple test case with two images, one in EPSG:2393 and another in EPSG:2392 this means that Mapserver thinks that images are 1000 kilometers apart and sharing the EPSG:2393 system that I used in the PROJECTION block.

Perhaps there could be an optional setting for LAYER level PROJECTION, both for individual images and tileindex layers, something like "init:internal_metadata".  It would mean that Mapserver would do first a query in a same manner than gdalinfo and ogrinfo for reading the native projection of the dataset.

Ok, once written this long I started to think about using PROJECTION AUTO and then I found this three-year-old RFC http://mapserver.org/development/rfc/ms-rfc-37.html

+1 for implementing it.

By the way, woudn't it be nice if desktop GIS like QGIS would show you also your Landsat archive images and not only the footprints in some pretty automatic way, let's say, after ticking a check box and setting the maximum scale denominator value?

-Jukka Rahkonen-



 

> -----Alkuperäinen viesti-----
> Lähettäjä: Etienne Tourigny [mailto:etourigny.dev at gmail.com]
> Lähetetty: 27. syyskuuta 2012 15:27
> Vastaanottaja: Rahkonen Jukka
> Kopio: gdal-dev at lists.osgeo.org
> Aihe: Re: [gdal-dev] Gdaltindex with -t_srs and Mapserver
> 
> Jukka,
> 
> nice that you noticed this new feature I added - was about to 
> advertise it here!
> 
> The goal of adding this feature was not to make it available in 
> mapserver, but for using in desktop applications as a reference for 
> multiple files with different projections (e.g. landsat archives).
> 
> cheers
> Etienne
> 
> On Thu, Sep 27, 2012 at 6:07 AM, Jukka Rahkonen 
> <jukka.rahkonen at mmmtike.fi> wrote:
> > Hi,
> >
> > I had a try with gdaltindex and the new -t_srs option that is 
> > discussed in http://trac.osgeo.org/gdal/ticket/4773. It seems to be 
> > as Even was thinking in the very beginning and Mapserver does not 
> > work with tileindex which is containing reprojected bounding boxes. 
> > Images with BBOX in the native projection are shown but not the 
> > others. This line
> appears into Mapserver log:
> > msDrawRasterLayerGDAL(): Error in overlap calculation.
> >
> > It might indeed be good to emit a warning about Mapserver 
> > incompability. It would be very nice if Mapserver supports this kind 
> > of
> tileindeces.
> >
> > -Jukka Rahkonen-
> >
> > _______________________________________________
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> > gdal-dev at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/gdal-dev