AW: [mapserver-users] Mapserver Projection Errors

[SixDegrees]

OK. So if my image is in UTM 38N and I have a PROJECTION block in the layer
with the Proj.4 string for that projection, but the wms_src setting in the
layer metadata is epsg:4326, will Mapserver reproject the image into
epsg:4326 when queried? It sounds that way, but I want to be certain.


Rahkonen Jukka wrote:
> 
> Hi,
> 
> The layer wms_srs (as well as the map level wms_srs) helps in building the
> list of projections which you want to support for output.  I believe you
> can safely insert there a list of SRS/CRS valurs you want to offer for
> your clients. For the projections on that list you must have a
> corresponding line in the epsg file. WMS clients do not use
> &SRS=+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs, they want
> to use &SRS=4326.
> 
> -Jukka Rahkonen-
> 
> SixDegrees wrote:
> 
>> Well, that certainly seems to explain things. If I supply a wms_srs
>> setting,
> the errors disappear. Sadly, I do not have the epsg codes, only the proj4
> strings, and I'm not sure the WMS XML concocted by Mapserver is correct.
> If
> I supply
> 
>>   "wms_srs" "+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs"
> 
> for example, the GetCapabilities request generates the following layer:
> 
> <Layer queryable="0" opaque="0" cascaded="0">
>         <Name>MyImage</Name>
>         <Title>MyImage</Title>
>         <SRS>+proj=longlat</SRS>
>         <SRS>+ellps=WGS84</SRS>
>         <SRS>+towgs84=0,0,0,0,0,0,0</SRS>
>         <SRS>+no_defs</SRS>
>         <LatLonBoundingBox minx="51.4432" miny="35.7193" maxx="51.6412"
> maxy="35.8732" />
>         <BoundingBox SRS="+proj=longlat"
>                     minx="51.4432" miny="35.7193" maxx="51.6412"
> maxy="35.8732" />
> </Layer>
> 
> Note how each term in the projection is given its own SRS tag, and the SRS
> of the BoundingBox only uses the first element. This does not look right
> to
> me, although things seem to work OK, as before. The Mapserver
> documentation
> states that the layer will use the map-level wms_srs, which is defined as
> "init=epsg:4326", but I worry that if I supply that in the layer metadata,
> Mapserver will think this layer is already in that format and fail to
> reproject when the image is acually in, say, a UTM format.
> 
> I have no way of retrieving or constructing the actual epsg code for each
> layer; most often it simply isn't in the file in any form other than
> Proj.4.
> If the layer-level wms_srs needs the actual epsg code of the file the
> layer
> references, then this is never going to work.
> 
> Thank you very much for taking the time to sort this all out, though. It's
> much, much farther than I ever would have got on my own.
> 
> 
> 
> 
> Eichner, Andreas - SID-NLK wrote:
>>
>> The error is caused by the msOWSPrintBoundingBox() function during the
>> GetCapabilities request because there's no {ows,wms}_srs metadata set.
>> The used function msOWSGetEPSGProj() tries to fall back to the
>> projections "init=" parameter but isn't available here.
>> It seems the whole thing is used to support bounding boxes for multiple
>> coordinate systems in the GetCapabilities document. This might only have
>> an effect if using WMS v1.3.0, {ows,wms}_bbox_extended metadata set to
>> "true" and {ows,wms}_srs projection list with more than one entry. In
>> such a case the original layer extent must be reprojected in  the listed
>> SRS which might fail. In your case this might have no negativ impact
>> beside the error message.
>> To get rid off the message you need to set a {ows,wms}_srs metadata at
>> layer level. It seems to be used to advertise the layer's CRS and build
>> the multi BBOX feature only. Altough it might not harm you it might
>> cause trouble in the future....
>>
>>
>>> LAYER
>>>    NAME "test_image"
>>>    EXTENT 51.44325 35.71925 51.64125 35.87325
>>>    METADATA
>>>       "wms_title" "test_image"
>>>       "wms_extent" "51.44325 35.71925 51.64125 35.87325"
>>>    END
>>>    PROCESSING "SCALE=AUTO"
>>>    PROCESSING "SCALE_BUCKETS=256"
>>>    TYPE RASTER
>>>    DATA "/data/geodata/yongbyon/test_image.vrt"
>>>    PROJECTION
>>>       "+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs"
>>>    END
>>> END
>> _______________________________________________
>> 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/Mapserver-Projection-Errors-tp6908527p6917339.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/Mapserver-Projection-Errors-tp6908527p6917647.html
Sent from the Mapserver - User mailing list archive at Nabble.com.