[Qgis-developer] Warning from DigitizingTools about CRS mismatch

[Casper Børgesen (CABO)]

Hi Bernhard

Thanks for your answer.

Yes I know that QGIS tries hard to determine the SRS-id which matches the values of the PRJ file. But my main issue is why it displays the warning only on one computer and not the others (same QGIS project with same data)?

Which mechanisms could trigger the difference in whether the warning should be shown or not?

We are running QGIS 2.14.0 64 bit on Windows 7.


Regards Casper


-----Original Message-----
From: Qgis-developer [mailto:qgis-developer-bounces at lists.osgeo.org] On Behalf Of Bernhard Ströbl
Sent: 8. april 2016 10:38
To: qgis-developer at lists.osgeo.org
Subject: Re: [Qgis-developer] Warning from DigitizingTools about CRS mismatch

Hi Casper,

DigitizingTools compares _only_ the SRS-id (SRS =
SpatialReferenceSystem) of the project and the layer. If they missmatch the warning is thrown so the user gets a hint why certain functions are greyed out.
Thus relevant is not the prj file but the SRS assigned to the layer and the project in their properties. To solve this issue: if they share a common projection, go in the layer properties and choose the same SRS as the project's from the list of projections.
Background (AFAIK): In Shapefiles the data do not carry information on their SRS (like e.g. in PostGIS or gml). This information is contained in the (optional) prj file. QGIS reads the prj file and assigns the first matching SRS to the data (matching = definition is identical). If there is none matching, a USER-SRS is created with the projection information given in the prj file.

Bernhard

Am 08.04.2016 um 10:10 schrieb Casper Børgesen (CABO):
> Hi!
>
> I have a user who constantly get a yellow warning from QGIS when he enables editing on set of specific shape files. The message is:
>
> DigitizingTools: Amend Line is disabled because layer CRS and project CRS do not match!
>
> The project CRS is EPSG:25832. The shape file has the following .prj file:
>
> PROJCS["ETRS_1989_UTM_Zone_32N",GEOGCS["GCS_ETRS_1989",DATUM["D_ETRS_1
> 989",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",
> 0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercato
> r"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0
> ],PARAMETER["Central_Meridian",9.0],PARAMETER["Scale_Factor",0.9996],P
> ARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]
>
> In "layer properties/General/Coordinate reference system", QGIS displays "Selected CRS (EPSG: 3044, ETRS89 / ETRS-TM32".
>
> If he enables editing on a shape file with the following .prj file, it doesn't happen:
>
> PROJCS["ETRS89_UTM_zone_32N",GEOGCS["GCS_ETRS_1989",DATUM["D_ETRS_1989
> ",SPHEROID["GRS_1980",6378137,298.257222101]],PRIMEM["Greenwich",0],UN
> IT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],P
> ARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",9],PARAM
> ETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETE
> R["false_northing",0],UNIT["Meter",1]]
>
> The strange thing is that this only happens on his computer not on a couple of other machines we have tried on.
>
> If there indeed is a CRS mismatch it make sense, but he is the only of our users experiencing this.
>
>
> Regards, Casper
>
>
>


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