[Qgis-user] RE: [Qgis-community-team] Problem changing a shapefile's coordinates

[Alister Hood]

Hi,

> -----Original Message-----
> From: qgis-community-team-bounces at lists.osgeo.org
[mailto:qgis-community-team-
> bounces at lists.osgeo.org] On Behalf Of giannis Nj
> Sent: Tuesday, 27 September 2011 10:53 p.m.
> To: qgis-user at lists.osgeo.org; qgis-community-team at lists.osgeo.org
> Subject: [Qgis-community-team] Problem changing a shapefile's
coordinates
> 
> Hello,
> 
> I have a .tiff file and a .shp one, showing the same area in the map
but they
> come in different coordinates. From the Properties of these files I
give them
> the same projection (4326 - WGS84), same as the project properties,
but still
> they don't match. Actually, the coordinates of the shapefile remain
the same
> (different from the project's), something that I thought would change
by
> changing the CRS.

Like Micha said, assigning a different CRS to a layer does not change
the coordinates of features in the layer, it just tells QGIS which CRS
the coordinates are in, for the sake of 'on the fly' CRS transformation.
For a layer to show up in the correct place you must assign it the
correct CRS (if not already assigned), and either:
(1) enable 'on the fly' CRS transformation, or 
(2) save copy of the layer, transformed into the same CRS as the
project, as the other guys have described, and use that copy.

(1) is fine if you only need to display the layer.  If you need to do
some sort of spatial analysis using layers in different CRSs you
normally need to do (2), because many tools in QGIS require layers to be
in the same CRS.

> I guess it's not that simple to change the coordinates in a
> file, so i would like to ask how it is possible to manage this so that
the two
> files will come in the same coordinates. Is something in the settings
that i
> forget to do? Is this able in QGIS or i have to try on another GIS
program?
> 
> Thank you.

Regards,
Alister