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Hi Ramon,<br>
<br>
Not sure what going on with problem 1. Thats weird.<br>
<br>
I'm no expert on Problems 2 and 3 but I was derailed by the same
issue. Problem is that QGIS can't distinguish between GDA94, AGD84
and AGD66. It doesn't contain the required projection definition
files. These will all silently default to WGS84 (or WGS72
occasionally). This also true if you import mapinfo files with
these projections, QGIS doesn't recognise them and they default to
WGS84 which means they are upto 150m out of position (AGD84 V's
GDA94).<br>
<br>
My understanding is that the problem lies with Proj4, the projection
reference system used, but not developed by QGIS. We looked into
getting the bug squashed a few months ago but it didn't work out,
probably because QGIS has no control over Proj4<br>
<br>
Have a look at
<a class="moz-txt-link-freetext"
href="http://blog.gmane.org/gmane.comp.gis.gdal.devel/month=20060301">http://blog.gmane.org/gmane.comp.gis.gdal.devel/month=20060301</a>
for
another discussion on using AGD66 / AGD84. It also contains the
projection definitions. In theory you could create your own CRS
entries for your area. My solution was to swap programmes.<br>
<br>
I am yet to see a solution for the Windows format but I believe the
Linux version works if you insert the correct gsb files. <br>
<br>
I keep an eye out hoping this issue will get fixed as I really like
QGIS as a package, I just can't use it.<br>
<br>
-- <br>
Brett Adams<br>
<a href="http://www.spinifexgeophysics.com.au/">
Spinifex Geophysics</a><br>
0438 861 974<br>
<a class="moz-txt-link-freetext" href="SKYPE:brettadams_spinifex">SKYPE:brettadams_spinifex</a>
<br>
<br>
<br>
<br>
<br>
On 21/12/2010 5:50 PM, Micha Silver wrote:
<blockquote cite="mid:4D10784C.9080806@arava.co.il" type="cite">Ramon
Andinach wrote:
<br>
<br>
<blockquote type="cite">Hello,
<br>
<br>
I am wanting to take a set of points stored in csv format that
are in the projected CRS GDA94/MGA94 zone 51 (MGAz51) and end up
with a csv file with the same points in CRS AGD84/AMG zone 51
(AMGz51). Being able to do this is useful for reconstructing
some historical datasets that I deal with.
<br>
</blockquote>
<br>
If all you need is the new AMG z51 coordinates, you might want to
try using cs2cs to do the conversion. You could script this to
create a new CSV file from the original with two new columns for
the new coord pair.
<br>
Here's a one liner to get started (tested on linux):
<br>
while read line; do echo $line | gawk -F , '{print $13"\t"$12}' |
cs2cs +init=epsg:28351 +to +init=epsg:20251; done <
MGAOnlyAC.csv
<br>
<br>
Columns 12 and 13 are the N and E coords, but in "reverse" order.
The gawk output gets piped straigt into the cs2cs utility, which
then dumps (to the screen, at this point) the coordinates,
transformed from EPSG 28351 (MGA z51 ) to EPSG 20251 (AMG94 z51)
<br>
<br>
<blockquote type="cite">I was intending to use the following path,
but have hit a few problems on the way. These are using qgis 1.6
on win7-64bit by osgeo, and was updated last thursday. At least
Problem 1 has been duplicated using qgis 1.6 on ubuntu 10.4, the
others I have yet to have an opportunity to test.
<br>
<br>
1. Import CSV using the Delimited Text Plugin (Problem 1).
<br>
2. Save as a shape file in MGAz51.
<br>
3. Load shape file
<br>
4. Export to AMGz51 using either;
<br>
a. Vector -> Data Management Tools -> Export to New
Projection (Problem 2), or
<br>
b. Save As and select a different CRS (Problem 3)
<br>
5. Load new shape file.
<br>
6. Extract coordinates using Vector -> Geometry Tools ->
Export/Add Geometry Columns and then
<br>
7. Save As a CSV.
<br>
<br>
So my first question is, is this path reasonable? Is there a
better way?
<br>
<br>
Problem 1.
<br>
I experienced problems importing a text file. In the Delimited
Text dialogue box the file appears to be correctly parsed, and I
can select the correct X and Y fields (East_MGA94 and
North_MGA94 respectively). However on import data is scattered
all over the place, and most fields do not have data in the X
and Y columns. This is weird, and I don't see why. Could some
one explain?
<br>
<br>
What I really don't get is why this file,
<br>
<a class="moz-txt-link-freetext" href="http://members.westnet.com.au/ramon_et_al/files/MGAOnlyAD.csv">http://members.westnet.com.au/ramon_et_al/files/MGAOnlyAD.csv</a>
<br>
does not import correctly when this file:
<br>
<a class="moz-txt-link-freetext" href="http://members.westnet.com.au/ramon_et_al/files/MGAOnlyAC.csv">http://members.westnet.com.au/ramon_et_al/files/MGAOnlyAC.csv</a>
<br>
does? There is only one column difference, and it does not
remove the columns that would create duplicate headers at an 8
column width.
<br>
<br>
</blockquote>
I think there's an empty column at the end of the problem CSV file
with no header, then after that another column called Item. i.e.
after DateSampled there are two commas. That might be confusing
the import...
<br>
<br>
Regards,
<br>
Micha
<br>
<blockquote type="cite">Problem 2.
<br>
Translating from MGA94z51 to GDA94 or WGS84 is successful.
<br>
But any of these to AMG84z51 fails silently after creating the
shape file.
<br>
<br>
Equally, AMG84z51 to any of these fails silently.
<br>
<br>
I don't know what the problem is. If the error is logged
somewhere, and someone can tell me where to look I'll hunt it
down and post what it says.
<br>
<br>
For reference I have also tried this on a test file that *only*
contains the coordinates, and hence no duplicate headers at 8
character width, and had the same problem.
<br>
<br>
Problem 3.
<br>
Translating using Save As also fails but gives an error.
<br>
Exception : forward transform of 2.11507, -0.524793 failed with
error: failed to load datum shift file.
<br>
<br>
Running from AMG84z51 to MGA94z51 gives a very similar error,
except gives the numbers 2.11507, -0.525033
<br>
<br>
<br>
Does anyone have any suggestions?
<br>
-ramon._______________________________________________
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<br>
<br>
</blockquote>
<br>
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</blockquote>
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