[Qgis-developer] Unknown CRS problem

[Martin Dobias]

On Tue, Jan 11, 2011 at 10:11 AM, Paolo Cavallini <cavallini at faunalia.it> wrote:
> Il giorno mar, 11/01/2011 alle 11.05 +0200, Micha Silver ha scritto:
>
>> > So if they work without reprojection, everything works smoothly, and
>> > they do not see anything wrong with that.
>>
>> Not entirely correct. As QGIS works now, each new project
>> starts in Lon/Lat WGS84. If I all my layers are in the same
>> projected CRS I don't notice any problem *until* I want to
>> measure something ;-(
>
> You are right, I was unclear: I meant, they do not see any problem if
> they use other (proprietary) software. In qgis they have to define their
> default CRS.

My idea was that if they have layers with unknown CRS, also the
project's CRS would be set to unknown. So no reprojection would happen
and no warnings shown. Even measuring could work to some degree -
assuming planar coordinates, with unknown units. Warnings would be
issued only when user explicitly does an action where known CRS is
necessary - e.g. change project CRS, add a layer with different
(known) CRS. There could be a "learn more" button leading to a brief
explanation of CRS, projections and why is it good to have them in
order - we could educate our users :)

Martin