[Qgis-developer] Warning from DigitizingTools about CRS mismatch

Sun Apr 10 23:02:21 PDT 2016

Hi,

it might be even easier to completely delete the prj file and either 
manually or by default set the layer's projection to the project's 
projection (as I understood they are both identical).

Bernhard

Am 09.04.2016 um 09:35 schrieb Bo Victor Thomsen:
> A futher note..
>
> The two projections 3044 and 25832 are *identical* regarding the proj4
> parameterdefinitions in the srs.db database, so QGIS might get confused
> when it opens a datasource, where the projection definition for the
> datasource is based on proj4.
>
> See
> http://gis.stackexchange.com/questions/115690/difference-between-etrs89-etrs-tm32-and-etrs89-utm-zone-32n
>
>
> You could do some kind of "cowboy" trick and remove the reference to
> 3044 from the srs.db database, table tbl_srs. The warnings from last
> post still apply :-)
>
> Regards
>
> Bo Victor Thomsen
> GIS & Database specialist
> Municipality of Frederikssund, Denmark
>
> Den 08/04/16 kl. 13:27 skrev Casper Børgesen (CABO):
>> Hi Bernhard
>>
>> I do follow your suggestions and they make perfectly sense. This is a
>> warning and I can probably safely disregard it in this case. I'm more
>> curious to discover why two computers using the same OS and QGIS
>> version seems to handle the CRS difference differently. My initial
>> mail was not specifically directed at DigitizingTools but it is (from
>> the user point of view) the source of the warning.
>>
>> What I suspect is that some setting somewhere, inside or outside QGIS,
>> might lead QGIS to behave differently - and I am curious to know :)
>>
>>
>> Regards Casper
>>
>> -----Original Message-----
>> From: Bernhard Ströbl [mailto:bernhard.stroebl at jena.de]
>> Sent: 8. april 2016 12:55
>> To: Casper Børgesen (CABO); qgis-developer at lists.osgeo.org
>> Subject: Re: [Qgis-developer] Warning from DigitizingTools about CRS
>> mismatch
>>
>> Hi Casper,
>>
>> I meant the CRS set in the layer's properties for the layer in question.
>> As you said both are using the same project so the project's CRS
>> should be the same in both cases.
>> In your first mail you state that the project's CRS is EPSG:25832 and
>> the layer's is EPSG:3044. There is the missmatch. Change this to
>> EPSG:25832 and all is fine. Check if the layer's CRS has been set to
>> EPSG:25832 on the working computer.
>> If the very same layer loads into the very same project with different
>> CRS on different machines then this is a question of QGIS in general
>> and has nothing to do with DigitizingTools (which is just pointing out
>> the difference).
>>
>> Bernhard
>>
>> Am 08.04.2016 um 12:43 schrieb Casper Børgesen (CABO):
>>> Hi Bernhard
>>>
>>> Since its the same QGIS project were opening on the different
>>> computers, I would expect them to behave the same. The current CRS
>>> (as stated in the bottom right of the QGIS window) is EPSG:25832 (OTF).
>>>
>>> I tried replacing the PRJ file of problematic shape file with the PRJ
>>> from the working shape file (see the first mail), but QGIS still
>>> displays the warning.
>>>
>>>
>>> Regards, Casper
>>>
>>> -----Original Message-----
>>> From: Bernhard Ströbl [mailto:bernhard.stroebl at jena.de]
>>> Sent: 8. april 2016 11:38
>>> To: Casper Børgesen (CABO); qgis-developer at lists.osgeo.org
>>> Subject: Re: [Qgis-developer] Warning from DigitizingTools about CRS
>>> mismatch
>>>
>>> Hi Casper,
>>>
>>> no idea why they behave differently. Are the settings for the layer's
>>> SRS on both machines the same?
>>> As I wrote, the warning is shown if there is a missmatch in the
>>> project's and the layer's SRS-id.
>>>
>>> Bernhard
>>>
>>> Am 08.04.2016 um 11:13 schrieb 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_Merca
>>>>> t
>>>>> o
>>>>> 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_19
>>>>> 8
>>>>> 9
>>>>> ",SPHEROID["GRS_1980",6378137,298.257222101]],PRIMEM["Greenwich",0],
>>>>> U
>>>>> N
>>>>> IT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"]
>>>>> ,
>>>>> P
>>>>> ARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",9],PAR
>>>>> A
>>>>> M
>>>>> ETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAME
>>>>> T E 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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