AW: [mapserver-users] Mapserver Projection Errors

Fri Oct 21 12:31:54 PDT 2011

If you make the request in EPSG:4326 then yes. 

Compare EPSG:2393
http://188.64.1.61/cgi-bin/mapserv?map=/usr/map/osm-mapserver_i.map&REQUEST=GetMap&SERVICE=WMS&VERSION=1.1.1&WIDTH=459&HEIGHT=353&LAYERS=sea&TRANSPARENT=TRUE&FORMAT=image%2Fpng&BBOX=2451307.6345609063,6544820.0,4359512.365439094,8012350.0&SRS=EPSG:2393&STYLES=

and EPSG:4326
http://188.64.1.61/cgi-bin/mapserv?map=/usr/map/osm-mapserver_i.map&REQUEST=GetMap&SERVICE=WMS&VERSION=1.1.1&WIDTH=459&HEIGHT=353&LAYERS=sea&TRANSPARENT=TRUE&FORMAT=image%2Fpng&BBOX=3.5931,49.05782679738563,45.5442,81.3208732026144&SRS=EPSG:4326&STYLES=

Best to take a GIS program as WMS client and open some known data file to the same project for having something to compare with. I like OpenJUMP because it can show the WMS request it is sending with Customize - BeanTools - Display_WMS_URL.  Download a nightly build, I am not sure if the release version has that tool already.

-Jukka Rahkonen-

SixDegrees wrote:

> 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
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>>
>
>
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