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

[SixDegrees]

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.
>>>>
>>>> --
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>>
>>
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