[Qgis-user] reference raster layers

[Bernardo Rossi Doria]

thank you michael,
I learned a lot from your suggestions ( I also refreshed my knowledge  
about projections) and I improved my capacity with qgis.
In fact I did not solve the problem of overlap my files with different  
original projection (UTM  Shapefile and WGS84 geoTIFF & shapefile)  
even if now they output in a closer position.
I guess now that as you suggested one of the two groups are not  
correcly referenced. I will discuss with providers.

Now a further question. I opened  qgis prefs and set the locale to  
"IT" or "it"  (italian). The first  gave russian characters as local;
I gor back to preferences and I looked for "en" again  but it had  
disapeared so  I tried the second wich is  is realy italian.
  But in this way I find impossible to get back to preferences because  
it is grayed... Is it a bug? I tried also via keyboard  (command ,)  
with no response.   How to go to preferences ?

Thank you all
Bernardo


Il giorno 08/ott/08, alle ore 21:29, Michael Neubauer ha scritto:

> Hello Bernando,
>
> first: When you change the projection (or better "spatial reference  
> system")
> in the project properties, it does not change the "spatial reference  
> system"
> in the data of your layer. Transforming your data to another "spatial
> reference system" would be a more complicated operation.
> But the good thing is, that with OTF activated, you do not have to  
> do that and
> you can superpone layers in different "spatial reference systems".
> So do not wonder that the projection of your layer stays the same,  
> when you
> change the projection of the whole project. Changing the projection  
> of the
> whole project should only have an effect on the coordinates which are
> displayed (right bottom of the screen)
>
> second: UTM is a "projected coordinate system" in contrast to  
> "geographic
> coordinate systems". "Geographic coordinate systems" treat the earth  
> like a
> sphere and work with degrees. "Projected coordinate systems" project  
> the
> spere (ball earth :-) ) on a flat surface and deal with other  
> numbers, which
> are defined in each coordinate system differently.
> UTM stands for "Universal Transverse Mercator" and you find it at  
> the bottom
> of "projected coordinate systems" in QGIS (between "geographic  
> coordinate
> systems" and "user defined coordinate systems").
> So you have to look for "WGS84 / UTM zone 32N" --> N for northern  
> hemisphere.
>
> So I hope that practical and theoretical information helps...  :-)
> Let me know if everything works
>
> bye
> michael

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