AW: [mapserver-users] Mapserver Projection Errors
SixDegrees
paulcarlisle at comcast.net
Fri Oct 21 15:41:00 EDT 2011
Excellent. I believe this means my problems will be solved simply by adding
the wms_src setting to each layer. Pity Mapserver doesn't just use the
map-level definition if it isn't defined, as the documentation states, but I
expect that will be solved in a future release.
Thanks again to everyone for all the patience and help.
Rahkonen Jukka wrote:
>
> 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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>>> mapserver-users at .osgeo
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>>>
>>
>>
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