[Qgis-user] KML to GoogleEarth

[Matt Boyd]

Walter,
the national standard isn't a legacy CRS. It's the one you'll need to
deal in and reference when you work with pretty much any government
departments and surveyors (at least that's how it is in Australia) and
if you want to work in meters and apply actual measurements to your
data. Land titles etc are all measured according to the national
standards (which do get updated over time).
I'd suggest you work out who the mapping is for, what it's purpose is
and choose a CRS to match those as well as observing any local laws
about using registered surveyors. Coordinates pulled out of GE won't
stand up in court if you're disputing a fenceline with a neighbour or
arguing with the local council about how far from the street you've
built your house.


regards
Matt
--------

Anyway: once i get those legacy data translated to WGS84, i think that
i should make all my new project-layers to use that CRS standard, for
the sake of GE compatibility and to avoid this confusion in future
-don't you think?





On Thu, Jul 28, 2011 at 10:03 PM, Walter Ludwick <wludwick at mac.com> wrote:
> Hey, Matt:  Thanks for taking the time to explain.
>
> I'm quite new to both QGIS and this whole problem domain, so it will take me some time to develop working understanding of all that you have said -which i do eventually hope to achieve!
>
> Meanwhile, taking my cue from the bottom line of your msg (below), i am now trying to find out what was the CRS used on that shapefile i am trying to export (see 1st file attached, "landplots.shp"), so that i can somehow generate .KML output from QGIS that makes more sense to Google Earth that the output i'm getting right now from QGIS (see 2nd file attached, "grandplandesign4.kml").
>
> FYI (in case it matters): this is about zoning (for agricultural purposes) a farm in coastal Portugal. The data comes from several different sources (including the topographer who did my land survey, and the municipal zoning authority, each of whom probably used an in-country datum from which to project, tho not necessarily the same one!), which data was aggregated in AutoCAD by a guy who works for me, before porting to QGIS. It was quite some time ago that these data were conveyed to me, tho, so it's a fair bit of work tracing it back to source!
>
> Once i find out about source data projection/CRS, i'm not quite sure how to do the xlation in QGIS, tho it sounds from what you've written like it should be easy enough...
> Anyway: once i get those legacy data translated to WGS84, i think that i should make all my new project-layers to use that CRS standard, for the sake of GE compatibility and to avoid this confusion in future -don't you think?
>
> Thanks again!  Yours, /w
>
>
>> Date: Thu, 28 Jul 2011 20:16:22 +1000
>> From: Matt Boyd <mattslists at gmail.com>
>> Subject: Re: [Qgis-user] KML to GoogleEarth
>> To: qgis-user <qgis-user at lists.osgeo.org>
>> Message-ID:
>>       <CAFgHUGKnUDYfEEpoGkwfKNcZ8uKhmZgmXW+uxAmFxRaW0J1Cnw at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Hi Walter,
>> I'm not sure what your understanding of qgis is but it deals with
>> pretty much every projection you can throw at it and the project
>> projection/CRS shouldn't really cause any issues if all the
>> projections are set correctly and the translations are working.
>>
>> Project CRS: the projection you'll see displayed on the map on the screen.
>>
>> Layer/item CRS: with on the fly reprojection enabled you can load a
>> file with pretty much any projection and QGIS will reproject the data
>> as required, it won't change the projection of the file you've loaded
>> the and if you want to reproject it permanently you'll need to go the
>> "save as" route and tell it what projection you want it to save the
>> new file in. When you create a new vector layer you have the option to
>> create it in the project or any other CRS.
>>
>> eg: You're able to load a file with CRS "A" into a project with CRS
>> "B" then load another file with CRS "C" and save the file that's CRS
>> "A" as CRS "D".
>>
>> The disadvantage to the flexibility of all of this is that
>> occasionally QGIS won't find the CRS or the projection file or you'll
>> get confused as to which CRS the file/layer your working in.
>>
>> The point to what I'm saying is that you shouldn't need to create a
>> new project or worry too much about the default CRS if what you want
>> to do is reproject the vector files so they're compatible with GE. You
>> do need to know what the CRS of the in and out files are though.
>>
>> If you're able to send me through a small file as an example to show
>> what you want to do I can have a look.
>>
>> Regards
>> Matt
> .........
>
>