[Qgis-user] Fwd: gfx in WSG 84 added to another CRS (EPSG:3021)

[Johan Nilsson]

If i said in the beguinning of my post I can transform, by save layer as
shape, and there choose the RT90 coordinate-system (it say it is in wsg
84). It just when I add a different layer, the transformation to metric
system, it's fail.

/Cheers

---------- Forwarded message ----------
From: Bo Victor Thomsen <bo.victor.thomsen at gmail.com>
Date: 2012/9/23
Subject: Re: [Qgis-user] gfx in WSG 84 added to another CRS (EPSG:3021)
To: Johan Nilsson <joni8135 at gmail.com>



The QGIS on-the-fly re-projection mechanism is able to manage both
different ellipsoids, projections and coordinate units.
Could the definition of EPSG:3021 in QGIS be wrong ? I'm am 100% sure, that
QGIS handles lat/long wgs84 (EPGS:4326) correct. What happens if you
convert and re-project the GPX file to shape/EPSG:3021 with ex. *ogr2ogr* (
www.gdal.org - no QGIS involved). Is your converted data then placed
correctly ?

Regards
Bo Victor Thomsen


09-2012 13:16, Johan Nilsson skrev:

Don't work
May it be that CRS have at least to components? Projections (Shape-models
of the earth) and Coordinate-system (defined as a grid from Equator and
Greenwich, but different according to the place on earth), and Enable 'on
the fly' reprojections don't change units from degrees to the metric
Coordinat-system?

/Cheers

2012/9/21 Bo Victor Thomsen <bo.victor.thomsen at gmail.com>

>
>    1. Choose a CRS for your _project_ using the menu "Settings" -->
>    "Project properties" --> Tab "Coordinate Reference System (CRS) and choose
>    the CRS from the dialog. Remember to enable "on the fly CRS transformation"
>    2. Open your layer(s). Don't think about the projection here.
>     3. Right-click on each of your layer(s) in the "Layers" dialog and
>    choose "Set layer CRS". If necessary, choose the CRS for the individual
>    layer.
>
> In some cases the CRS for a layer can't be inferred from the information
> in the layer's datafile or QGIS can't read it correctly. Executing step 3
> for each "problem" layer corrects this problem.
>
> Regards
> Bo Victor Thomsen
> Aestas-GIS
> Denmark
>
>
> Den 21-09-2012 09:23, Johan Nilsson skrev:
>
> When I click Layer-->'Add vector layer.....' I can browse for files, shp,
> gpx, and so on, but never chose an CRS in that menu. My Background map are
> in RT90 coordinate system in meters approx 1500000,6500000 m but gpx files
> come to 17  and 60 m (not degree), way ot of the map...
>
>
> /Cheers
>
> 2012/9/21 leyan ouyang <ouyang.leyan at hotmail.com>
>
>>  Yes it is possible, the option "on-the-fly reprojection" does just
>> that. Choose the main CRS as the project CRS (it will be used for distance
>> calculations, etc.). Then when you add a layer you can choose its CRS
>> individually, QGIS will do the transformation.
>>
>> Regards,
>>
>> Leyan
>>
>>  ------------------------------
>> Date: Fri, 21 Sep 2012 09:08:05 +0200
>> From: joni8135 at gmail.com
>> To: qgis-user at lists.osgeo.org
>> Subject: [Qgis-user] gfx in WSG 84 added to another CRS (EPSG:3021)
>>
>>
>> Hi.
>> I can transform gpx file from a GPS (WSG84) to an old swedisch CSR
>> EPSG:3021 (RT90 2,5 gon V metric coordinate system)) shape file, but I
>> whant to let the program transform on the fly.
>>
>>  I know that year 1999 Silicon graphic had it on there 'super coomputers'
>> and GIS-softwate, and I also see that QGIS have under menue:
>> *Settings-->Options-->CRS*-tab have an option to check 'on the fly
>> reprojection' in option.
>>
>> Under options-->CRS can you define default project CRS and defaut CRS to
>> what your add in layers, but If you have a lot of old files with diffenent
>> CRS it could be errors. Now Sweden is in transition from RT90 to SweRef99
>> (very near WSG84)
>>
>> Is it possible to add vector files with other CRS, or even rasters to a
>> project without transform it?
>>
>> /Cheers
>>
>>
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