[mapserver-users] Re: QGis 'Zoom to best scale' Not Working

Rahkonen Jukka Jukka.Rahkonen at mmmtike.fi
Tue Nov 22 23:36:48 PST 2011 

Hi,

If you haven't already asked from the QGis mailing list, I would say that the next thing to do is to ask what metadata element QGIs is using for zoom to best scale. After that we can check if it is included in the Mapserver GetCapabilities and how.


-Jukka Rahkonen-

> -----Alkuperäinen viesti-----
> Lähettäjä: mapserver-users-bounces at lists.osgeo.org 
> [mailto:mapserver-users-bounces at lists.osgeo.org] Puolesta SixDegrees
> Lähetetty: 22. marraskuuta 2011 22:15
> Vastaanottaja: mapserver-users at lists.osgeo.org
> Aihe: [mapserver-users] Re: QGis 'Zoom to best scale' Not Working
> 
> I'm requesting the layer. Interesting that grouped layers 
> cause problems; we
> have an identical mapfile with the groups commented out, so 
> I'll give that a
> try when I return to work and see if it has the same problem or not.
> 
> 
> Travis Kirstine wrote
> > 
> > Are you requesting the "MyGroup" layer or "MyImage", I'm not sure if
> > the group inherits the layer metadata (I'm sure someone on the list
> > knows).  I have noticed that when adding grouped layers in QGIS the
> > zoom to extent does not work however it will work when individual
> > layers are added.
> > 
> > Regards
> > 
> > On 22 November 2011 06:08, SixDegrees <paulcarlisle@> wrote:
> >> Sorry, I was wrong in the previous message; the resx and 
> resy settings do
> >> show up in the capabilities document. They make no 
> difference, however;
> >> the
> >> bounding box requested by QGis is still in error.
> >>
> >>
> >> SixDegrees wrote
> >>>
> >>> Thank you. I added wms_resx and wms_resy to my mapfile 
> with reasonable
> >>> values (and some unreasonable ones, just as tests). This makes no
> >>> difference. When I make a GetCapabilities request, the 
> layer's bounding
> >>> box is correct but it does NOT contain the resx or resy 
> settings, as I
> >>> believe it should.
> >>>
> >>> I don't know if this is a problem in my mapfile or in 
> MapServer. My
> >>> mapfile layer looks like this (file names changed for proprietary
> >>> reasons):
> >>>
> >>> LAYER
> >>>    NAME "MyImage"
> >>>    GROUP "MyGroup"
> >>>    EXTENT 75.80425 35.304 76.01625 35.476
> >>>    METADATA
> >>>       "wms_title" "MyImage"
> >>>       "wms_group_title" "MyGroup"
> >>>       "wms_extent" "75.80425 35.304 76.01625 35.476"
> >>>       "wms_srs" "EPSG:4326"
> >>>       "wms_resx" "1.0" # Note: these values are for 
> testing only. The
> >>> actual values have
> >>>       "wms_resy" "1.0" # also been tried, with no 
> success. They are
> >>> 5.90139233796e-06, -4.85244300668e-06
> >>>    END
> >>>    PROCESSING "SCALE=AUTO"
> >>>    PROCESSING "SCALE_BUCKETS=256"
> >>>    TYPE RASTER
> >>>    DATA "MyImage.vrt"
> >>>    PROJECTION
> >>>       "+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs"
> >>>    END
> >>> END
> >>>
> >>>
> >>>
> >>>
> >>> Rahkonen Jukka wrote
> >>>>
> >>>> Hi,
> >>>>
> >>>> WMS does not advertise by default the native resolution 
> of the data.  I
> >>>> have never tried but perhaps adding wms_resx, wms_resy 
> metadata into
> >>>> layer metadata would add that information into GetCapabilities
> >>>> http://mapserver.org/ogc/wms_server.html.
> >>>>  I do not know if QGis can utilise that information even 
> if it exists.
> >>>>
> >>>> -Jukka Rahkonen-
> >>>>
> >>>> SixDegrees wrote:
> >>>>
> >>>>> I'm not sure if this is a QGis problem or a problem with my
> >>>> Mapserver-generated WMS layer. When I load a WMS image in QGis,
> >>>> everything
> >>>> works as expected except when I select 'Zoom to best 
> scale' I get a
> >>>> Mapserver error stating that the bounding box is 
> illegal. And it is -
> >>>> the
> >>>> bounding box corner points in the getmap request are 
> identical. This
> >>>> selections is supposed to zoom in so the pixels 
> displayed are 1:1 or
> >>>> 100%
> >>>>
> >>>>> A look at the capabilities request returned by Mapserver and the
> >>>>> mapfile
> >>>>> and
> >>>> images involved don't show anything obviously wrong. Is 
> it possible
> >>>> that
> >>>> QGis is sending the wrong request? Or is something 
> missing from either
> >>>> the
> >>>> capabilities document or the mapfile layer?
> >>>>
> >>>>> I'm not really sure where to start looking to isolate 
> the problem.
> >>>>> Note
> >>>>> that
> >>>> if I load images directly instead of through Mapserver 
> WMS I am able to
> >>>> zoom
> >>>> to scale without any problem, which suggests a problem 
> with Mapserver,
> >>>> likely in the mapfile. I am using VRT files as 
> intermediaries between
> >>>> the
> >>>> Mapfile and the underlying NITF files; it seems that 
> Mapserver should
> >>>> be
> >>>> using the affine transform contained in the VRT to 
> determine proper
> >>>> scaling,
> >>>> but I'm not sure if that is sufficient. Are there 
> arguments that need
> >>>> to
> >>>> be
> >>>> placed in the Mapfile metadata to help WMS generation along? Or
> >>>> something
> >>>> that would cause items in the capabilities document to 
> be left out?
> >>>>
> >>>>> Using QGis 1.7.0 on Linux.
> >>>>
> >>>> --
> >>>> View this message in context:
> >>>> 
> http://osgeo-org.1803224.n2.nabble.com/QGis-Zoom-to-best-scale
> -Not-Working-tp7017776p7017776.html
> >>>> Sent from the Mapserver - User mailing list archive at 
> Nabble.com.
> >>>> _______________________________________________
> >>>> mapserver-users mailing list
> >>>> mapserver-users at .osgeo
> >>>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >>>> _______________________________________________
> >>>> mapserver-users mailing list
> >>>> mapserver-users at .osgeo
> >>>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >>>>
> >>>
> >>
> >>
> >> --
> >> View this message in context:
> >> 
> http://osgeo-org.1803224.n2.nabble.com/QGis-Zoom-to-best-scale
> -Not-Working-tp7017776p7020066.html
> >> Sent from the Mapserver - User mailing list archive at Nabble.com.
> >> _______________________________________________
> >> mapserver-users mailing list
> >> mapserver-users at .osgeo
> >> http://lists.osgeo.org/mailman/listinfo/mapserver-users
> >>
> > _______________________________________________
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> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
> > 
> 
> 
> --
> View this message in context: 
> http://osgeo-org.1803224.n2.nabble.com/QGis-Zoom-to-best-scale
> -Not-Working-tp7017776p7021775.html
> Sent from the Mapserver - User mailing list archive at Nabble.com.
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