<div dir="ltr">Hi all,<div><br></div><div>Allow my to weigh in my two cents.</div><div><br></div><div>Obviously the accuracy requirements all depend on the scale of the project. If you're only mapping the bank of a stretch of estuary, 2-5m accuracy should be ok. The accuracy you require will depend on the scale of the other habitats you mention. If you're mapping small features of the landscape, such as the dripline of a tree or the cross section of a small pond, ideally you want sub meter accuracy. I've been using a Leica Zeno 15 DGPS with reasonable success for similar projects. Under typical field conditions this gives me 20-50cm accuracy. </div><div><br></div><div>Abri</div></div><div class="gmail_extra"><br><div class="gmail_quote">On 25 May 2015 at 13:39, Andrew Akera <span dir="ltr"><<a href="mailto:akera.andrew@gmail.com" target="_blank">akera.andrew@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hello group members, mapping an area of 1-2kms radius is small, you can use a hand-held GPS for preliminary survey, the maps from Hand-held GPS is not accurate approximately (1-5 meters) its good for planning and decision making purposes, Differential GPS is the most and reliable instrument used for mapping large areas its accuracy level is approximately 5-10cm depending on the satellites available, Differential GPS and Total stations are good for cadastral mapping, so it will depend on the purpose of data collection and project <br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, May 20, 2015 at 3:46 PM, Aslam Parker <span dir="ltr"><<a href="mailto:Aslam.Parker@drdlr.gov.za" target="_blank">Aslam.Parker@drdlr.gov.za</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The accuracy of smartphone can vary from 5m (when u lucky) to 30m, but generally in the 10m range and dependant on many factors including number and geometry
of satellites, multipath, signal to noise ratio etc.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">However, the accuracy and the reliability of the position increases when the position is supplemented by WIFI and cell tower trilateration. Unfortunately, there
are no QC tools and you do not know the position quality.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">This is the advantage of GIS and survey grade class receivers, which has the option of doing differential correction.
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:africa-bounces@lists.osgeo.org" target="_blank">africa-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:africa-bounces@lists.osgeo.org" target="_blank">africa-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Losso Ekolo<br>
<b>Sent:</b> 20 May 2015 02:07 PM<span><br>
<b>To:</b> Africa local chapter discussions<br>
</span><span><b>Subject:</b> Re: [OSGeo Africa] Field mapping GPS suggestions please<u></u><u></u></span></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<p class="MsoNormal">Hi Taryn,<u></u><u></u></p><span>
<div>
<p class="MsoNormal"> A smartphone alone will give you a best accuracy of 5m and not all the time. To get a submeter accuracy you have to invest in a survey grade device and they are costly. Here's nice read with cost estimate.<u></u><u></u></p>
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<p class="MsoNormal"><a href="http://www.resource-analysis.com/Services/GPS" target="_blank">http://www.resource-analysis.com/Services/GPS</a><u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<div>
<p class="MsoNormal">Regards,<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Losso Ekolo<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Wed, May 20, 2015 at 1:54 PM, Wilhelm Herbst <<a href="mailto:wherbst@optron.com" target="_blank">wherbst@optron.com</a>> wrote:<u></u><u></u></p>
<div>
<div>
<p class="MsoNormal">Optron, who are the suppliers of Trimble in SA, will provide you with a handheld GPS with differential capabilities with sub meter (or even better if you want to spend more money)
capabilities.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
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<p> </p>
<p><img border="0" src="cid:image62f91a.JPG@573859a2.46a4fbae" width="800" height="130"></p><div><div>
<p> </p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:africa-bounces@lists.osgeo.org" target="_blank">africa-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:africa-bounces@lists.osgeo.org" target="_blank">africa-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Dean Ollis<br>
<b>Sent:</b> Wednesday, 20 May, 2015 1:52 PM<br>
<b>To:</b> <a href="mailto:africa@lists.osgeo.org" target="_blank">africa@lists.osgeo.org</a></span><u></u><u></u></p>
<div>
<div>
<p class="MsoNormal"><br>
<b>Subject:</b> Re: [OSGeo Africa] Field mapping GPS suggestions please<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">Hi, Taryn<br>
<br>
For the accuracy of 1m2 that you are aiming for, I don't think that a mobile phone or a hand-held GPS (no matter what brand!) are going to do the job. I am not a surveyor, but I think that you are going to need to at least use a differential GPS to get that
sort of accuracy. <br>
<br>
Maybe a surveyor on the list can provide you with advice as to the most cost effective way to delineate the habitat units that you are trying to map.<br>
<br>
Kind regards<br>
<br>
Dean<br>
<br>
----------------------------------------------------------- <br>
<span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Dean Justin Ollis
<i>Pr.Sci.Nat.</i> <br>
<b>The Freshwater Consulting Group</b> <br>
</span><br>
<br>
------- Original message -------<br>
<b>Subject: </b>Re: [OSGeo Africa] Field mapping GPS suggestions please<br>
<b>From: </b>Chris Berens<br>
<b>To: </b>Africa Local Chapter Discussions<br>
<b>Date: </b>2015/05/20 - 11:20<br>
<span style="font-family:"Arial","sans-serif""> </span><u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p>
<pre>Mobile phone GPS may give you an accuracy of 25m if you are lucky.<u></u><u></u></pre>
<pre>Maybe just draw your special areas in by hand on a 1:1000 field map<u></u><u></u></pre>
<pre>with a pencil crayon.<u></u><u></u></pre>
<pre>For mobile GIS/GPS try HGIS from Starpal, it will only run on a<u></u><u></u></pre>
<pre>Windows mobile OS but the demo works for free in Africa for<u></u><u></u></pre>
<pre>Environmental projects. Otherwise if you find an android device with a<u></u><u></u></pre>
<pre>decent clock you can run QGIS Android version.<u></u><u></u></pre>
<pre>Chris Berens<u></u><u></u></pre>
<pre>PLATO GISc 1308<u></u><u></u></pre>
<pre><a href="http://www.mapland.co.za" target="_blank">www.mapland.co.za</a><u></u><u></u></pre>
<pre><a href="tel:%2B27%20%280%2982%20567%209322" target="_blank">+27 (0)82 567 9322</a><u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>On 20 May 2015 at 10:27, Gerhardus Geldenhuis<u></u><u></u></pre>
<pre><a href="mailto:gerhardus.geldenhuis@gmail.com" target="_blank"><gerhardus.geldenhuis@gmail.com></a> wrote:<u></u><u></u></pre>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<pre>Hi,<u></u><u></u></pre>
<pre>I am no expert but I can't imagine that a mobile phone will be equivalent in<u></u><u></u></pre>
<pre>accuracy to something like a Trimble. You most certainly pay for the brand<u></u><u></u></pre>
<pre>but you also pay of the more accurate internal clock that plays a crucial<u></u><u></u></pre>
<pre>part in the error margin. I have used a Garmin 60CSx with a lot of success<u></u><u></u></pre>
<pre>doing Geological mapping. If you add an external antenna that could also<u></u><u></u></pre>
<pre>help with accuracy.<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>Regards<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>On 20 May 2015 at 08:21, Taryn Riddin <a href="mailto:taryn.riddin@live.co.za" target="_blank"><taryn.riddin@live.co.za></a> wrote:<u></u><u></u></pre>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<pre> <u></u><u></u></pre>
<pre>Good day<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>Is anyone able to give me some advice please on choosing a GPS setup to<u></u><u></u></pre>
<pre>map estuarine habitats in the field? Our SA estuaries are often very narrow<u></u><u></u></pre>
<pre>(1 to 2 km wide) and habitats small. We distinguish between supratidal salt<u></u><u></u></pre>
<pre>marsh, intertidal salt marsh, reeds and sedges, among other habitats. Reeds<u></u><u></u></pre>
<pre>and sedges often form a very narrow band along an estuary. Accuracy needs<u></u><u></u></pre>
<pre>to be as close as possible to 1 m2, perhaps even better.<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>Someone suggested using a windows / android phone running ArcGIS Collector<u></u><u></u></pre>
<pre>as the GPS in them is as good as a Trimble and also cheaper? It could also<u></u><u></u></pre>
<pre>be a separate GPS linked to a tablet, not necessarily a single hand help GPS<u></u><u></u></pre>
<pre>unit with mapping options. We use ArcGIS software for final map productions<u></u><u></u></pre>
<pre>and analysis.<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>I am not very clued up on these aspects so any advise would be greatly<u></u><u></u></pre>
<pre>appreciated.<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>Many thanks in advance,<u></u><u></u></pre>
<pre>Taryn<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>________________________________<u></u><u></u></pre>
<pre>Research Associate - Botany Department<u></u><u></u></pre>
<pre>Nelson Mandela Metropolitan University<u></u><u></u></pre>
<pre>P.O. Box 77000<u></u><u></u></pre>
<pre>Port Elizabeth<u></u><u></u></pre>
<pre>6070<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>_______________________________________________<u></u><u></u></pre>
<pre>Africa mailing list<u></u><u></u></pre>
<pre><a href="mailto:Africa@lists.osgeo.org" target="_blank">Africa@lists.osgeo.org</a><u></u><u></u></pre>
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</blockquote>
<pre> <u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>--<u></u><u></u></pre>
<pre>Gerhardus Geldenhuis<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<pre>_______________________________________________<u></u><u></u></pre>
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<pre>_______________________________________________<u></u><u></u></pre>
<pre>Africa mailing list<u></u><u></u></pre>
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<pre>.<u></u><u></u></pre>
<pre> <u></u><u></u></pre>
<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal"><br>
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You can UNSUBSCRIBE at <a href="http://lists.osgeo.org/mailman/listinfo/africa" target="_blank">http://lists.osgeo.org/mailman/listinfo/africa</a><br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr">Abri de Buys<div>Technical Officer</div><div>SAEON Fynbos Node</div><div>Tel: + 27 21 799 8683</div><div><a href="http://www.saeon-fynbos.org/" style="color:rgb(17,85,204);background-color:rgb(255,255,255);font-size:13px;font-family:arial,sans-serif" target="_blank">http://www.saeon-fynbos.org</a></div><div><img src="cid:ii_14975479f3b17fea" width="200" height="68"><img src="cid:ii_149755af80a8afed" width="200" height="78"><br></div></div></div></div></div>
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