[Qgis-user] QGIS Server Projection Problems

[Bernhard Ströbl]

Hi Emma,

for me it is not quite clear, what you are trying to do. So I would like 
to ask you some questions:
I understand that your data and project are in EPSG:4326, is that true?
What CRS is your client using? Is it EPSG:3452?
What client do you use?
Are you sure your client does the reprojection or is it requesting the 
WMS map in the CRS it needs?

To further investigate I propose you use QGIS desktop as client. Set the 
project's CRS to EPSG:4326 and load the data (GML/shp) and load from 
mapserver. Do they match? Load the map from QGIS server, do they match? 
Do the same with another project with CRS EPSG:3452. What happens?

Bernhard

Am 17.10.2013 18:20, schrieb Hung,Emma [Ontario]:
> I am running Ubuntu 12.04 with qgis (2.0.1), qgis-mapserver and
> libapache2-mod-fcgid packages installed using apt-get install.
> I am trying to serve up data from gml files to a WMS client (I've also
> tried shape files). The source is in lat/lon EPSG:4326 projection, I've
> specified this same projection for the project (or at least I believe I
> have). Once I save the project I then use the .qgs file as my "mapfile"
> for the qgis mapserver. When I compare the output from QGIS Server and
> MapServer in my WMS client I observe that the projections do not match
> (note the source is the same for both), I see the same distortion
> whether I use gml or shape files as a source. I'm confident that the
> result from MapServer is correct because it matches the original images
> from the producing software. I've attached a screen shot to this email
> to illustrate the distortion, the green areas are from Map Server and
> the yellow are from QGIS Server.
>
> Here's a snippet from the destinationsrs block:
>          <projections>1</projections>
>          <destinationsrs>
>              <spatialrefsys>
>                  <proj4>+proj=longlat +ellps=WGS84 +datum=WGS84
> +no_defs</proj4>
>                  <srsid>3452</srsid>
>                  <srid>4326</srid>
>                  <authid>EPSG:4326</authid>
>                  <description>WGS 84</description>
>                  <projectionacronym>longlat</projectionacronym>
>                  <ellipsoidacronym>WGS84</ellipsoidacronym>
>                  <geographicflag>true</geographicflag>
>              </spatialrefsys>
>          </destinationsrs>
> and here's the srs block:
>              <srs>
>                  <spatialrefsys>
>                      <proj4>+proj=longlat +ellps=WGS84 +datum=WGS84
> +no_defs</proj4>
>                      <srsid>3452</srsid>
>                      <srid>4326</srid>
>                      <authid>EPSG:4326</authid>
>                      <description>WGS 84</description>
>                      <projectionacronym>longlat</projectionacronym>
>                      <ellipsoidacronym>WGS84</ellipsoidacronym>
>                      <geographicflag>true</geographicflag>
>                  </spatialrefsys>
>              </srs>
> and the SpatialRefSys block:
>         <SpatialRefSys>
>              <ProjectCRSProj4String type="QString">+proj=longlat
> +ellps=WGS84 +datum=WGS84 +no_defs</ProjectCRSProj4String>
>              <ProjectCrs type="QString">EPSG:4326</ProjectCrs>
>              <ProjectionsEnabled type="int">1</ProjectionsEnabled>
>          </SpatialRefSys>
>
> The WMS client is re-projecting to suit its needs.
>
> Please forgive me I'm not a GIS expert my background is computer science
> and I work with research meteorologists so my grasp on geographic
> projections is not great, mathematically I get what needs to be done but
> I'm not familiar with all the lingo for describing them.
>
> I'd appreaciate any insight you might have on this issue. I quite like
> the WYSIWYG aspect of creating the map file and would love to use the
> QGIS mapserver instead of MapServer, but if I can't fix this I'll have
> to settle I suppose. Thank-you!
>


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