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<div class="moz-cite-prefix">Thanks Melissa<br>
<br>
The NGI DEM is probably a lot more accurate (and higher
resolution) than SRTM so it would be worth scripting that GRASS
process if you're concerned about accuracy. <br>
<br>
The NGI DEM if I remember correctly is derived from stereo
orthophotos, more recent ones being done 100% digitally. SRTM on
the other hand has many artefacts. I've used this fixed-up SRTM
data before: <a class="moz-txt-link-freetext" href="http://www.viewfinderpanoramas.org/dem3.html">http://www.viewfinderpanoramas.org/dem3.html</a>. <br>
<br>
Gavin<br>
<br>
On 28/04/2015 08:11, Melissa Akoue Mve wrote:<br>
</div>
<blockquote
cite="mid:CAM86ncsBWDjSVBkw-7vdCw9hK5dc+vi61ZqS-+WEP=sTX3L3tA@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>
<div>
<div>
<div>
<div>Hi Gavin and Walter,<br>
<br>
</div>
Sorry for my late response. I got caught in meetings
and only managed to try out your suggestions late on
friday and this morning.<br>
<br>
</div>
I tried both ways and they both work well. Walter's
suggestion of downloading the SRTM 30m DEMs is the faster
method because I can download the images as geotiffs and
load them in directly without Grass or any other
manipulation. However I have learnt a lot from trying
Gavin's method too.<br>
<br>
</div>
Thank you both for your invaluable assistance. This
discussion group is very valuable tool.<br>
<br>
</div>
Regards,<br>
</div>
Melissa<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2015-04-24 13:50 GMT+02:00 Jean Paul
Ngalams <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:jpngalams@gmail.com" target="_blank">jpngalams@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Thank you Gavin for your answer to Melissa's
question; I had the same preoccupation. </div>
<div class="gmail_extra">
<div>
<div class="h5"><br>
<div class="gmail_quote">On Fri, Apr 24, 2015 at 12:17
PM, Gavin Fleming <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:gavin@kartoza.com" target="_blank">gavin@kartoza.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Hi Melissa<br>
<br>
I've just done one of the NGI ort files
(2631AA07.ort) in GRASS (result below). Pretty
much everything you need is at <a
moz-do-not-send="true"
href="http://grasswiki.osgeo.org/wiki/Import_XYZ"
target="_blank">http://grasswiki.osgeo.org/wiki/Import_XYZ</a>.
Note there are multiple spaces so you'll have
to use the trick on that page to collapse
multiple spaces to single spaces. Also note
the coordinates are south facing TM so you'll
have to do one zone at a time then project
them together, or project all to UTM or Albers
first. <br>
<br>
<img
src="cid:part4.09010409.09020306@gmail.com"
alt=""><br>
<br>
You should be able to import directly in QGIS
(which uses GDAL) after re-ordering the data
as per <a moz-do-not-send="true"
href="http://www.gdal.org/frmt_xyz.html"
target="_blank">http://www.gdal.org/frmt_xyz.html</a>.
However on this one I tried, GDAL thinks the
number of lines doesn't match the size of the
grid it has calculated so it fails., so I just
switched to GRASS. <br>
<br>
Good luck and let us know when you've done it
(and how you did it).<br>
<br>
Gavin
<div>
<div><br>
<br>
On 24/04/2015 11:09, Melissa Akoue Mve
wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div>
<div>Hi All,</div>
<div> </div>
<div>I need to do a slope analysis of the
whole Western Cape area. I had planned
to do this with the raster tool set in
QGIS but after getting the DEM's from
the NGI I discovered their DEMs are in a
.ort format which is not a standard GDal
format. </div>
<div> </div>
<div>I was informed that the only way to
load this .ort into QGIS is by
converting it to a CSV and then loading
the CSV file into QGIS, and then
converting it to raster when in DEM. I
have tried this but it is laborious and
will take too long because there
are more than 50 NGI DEMs that make up
the Western Cape area.</div>
<div> </div>
<div>Does anyone know of a simpler way to
load the .ort file. I have searched
for ways to convert the .ort to a
geotiff but I havent been successful
yet,</div>
<div> </div>
<div>Kind Regards,</div>
<div>Melissa Akoue Mve,</div>
<div> </div>
<div> </div>
<div> </div>
<br>
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<pre class="moz-signature" cols="72">--
Gavin Fleming
t: 0218620670
w: 0218630660
c: 0845965680
f: 0866164820
Paarl
South Africa
18°59'19.6"E 33°44'46.1"S</pre>
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