[OSGeo Africa] Field mapping GPS suggestions please

Mon May 25 04:39:33 PDT 2015

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

On Wed, May 20, 2015 at 3:46 PM, Aslam Parker <Aslam.Parker at drdlr.gov.za>
wrote:

>   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.
>
>
>
> 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.
>
>
>
> This is the advantage of GIS  and survey grade class receivers, which has
> the option of doing differential correction.
>
>
>
>
>
>
>
>
>
>
>
> *From:* africa-bounces at lists.osgeo.org [mailto:
> africa-bounces at lists.osgeo.org] *On Behalf Of *Losso Ekolo
> *Sent:* 20 May 2015 02:07 PM
> *To:* Africa local chapter discussions
> *Subject:* Re: [OSGeo Africa] Field mapping GPS suggestions please
>
>
>
> Hi Taryn,
>
>              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.
>
>
>
> http://www.resource-analysis.com/Services/GPS
>
>
>
> Regards,
>
>
>
> Losso Ekolo
>
>
>
>
>
>
>
> On Wed, May 20, 2015 at 1:54 PM, Wilhelm Herbst <wherbst at optron.com>
> wrote:
>
> 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.
>
>
>
>
>
>
>
>     *From:* africa-bounces at lists.osgeo.org [mailto:
> africa-bounces at lists.osgeo.org] *On Behalf Of *Dean Ollis
> *Sent:* Wednesday, 20 May, 2015 1:52 PM
> *To:* africa at lists.osgeo.org
>
>
> *Subject:* Re: [OSGeo Africa] Field mapping GPS suggestions please
>
>
>
> Hi, Taryn
>
> 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.
>
> 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.
>
> Kind regards
>
> Dean
>
> -----------------------------------------------------------
> Dean Justin Ollis *Pr.Sci.Nat.*
> *The Freshwater Consulting Group*
>
>
> ------- Original message -------
> *Subject: *Re: [OSGeo Africa] Field mapping GPS suggestions please
> *From: *Chris Berens
> *To: *Africa Local Chapter Discussions
> *Date: *2015/05/20 - 11:20
>
>
>
>
> Mobile phone GPS may give you an accuracy of 25m if you are lucky.
>
> Maybe just draw your special areas in by hand on a 1:1000 field map
>
> with a pencil crayon.
>
> For mobile GIS/GPS try HGIS from Starpal, it will only run on a
>
> Windows mobile OS but the demo works for free in Africa for
>
> Environmental projects. Otherwise if you find an android device with a
>
> decent clock you can run QGIS Android version.
>
> Chris Berens
>
> PLATO GISc 1308
>
> www.mapland.co.za
>
> +27 (0)82 567 9322
>
>
>
>
>
> On 20 May 2015 at 10:27, Gerhardus Geldenhuis
>
> <gerhardus.geldenhuis at gmail.com> <gerhardus.geldenhuis at gmail.com> wrote:
>
>  Hi,
>
> I am no expert but I can't imagine that a mobile phone will be equivalent in
>
> accuracy to something like a Trimble. You most certainly pay for the brand
>
> but you also pay of the more accurate internal clock that plays a crucial
>
> part in the error margin. I have used a Garmin 60CSx with a lot of success
>
> doing Geological mapping. If you add an external antenna that could also
>
> help with accuracy.
>
>
>
> Regards
>
>
>
> On 20 May 2015 at 08:21, Taryn Riddin <taryn.riddin at live.co.za> <taryn.riddin at live.co.za> wrote:
>
>
>
> Good day
>
>
>
> Is anyone able to give me some advice please on choosing a GPS setup to
>
> map estuarine habitats in the field?  Our SA estuaries are often very narrow
>
> (1 to 2 km wide) and habitats small.  We distinguish between supratidal salt
>
> marsh, intertidal salt marsh, reeds and sedges, among other habitats.  Reeds
>
> and sedges often form a very narrow band along an estuary.  Accuracy needs
>
> to be as close as possible to 1 m2, perhaps even better.
>
>
>
> Someone suggested using a windows / android phone running ArcGIS Collector
>
> as the GPS in them is as good as a Trimble and also cheaper?  It could also
>
> be a separate GPS linked to a tablet, not necessarily a single hand help GPS
>
> unit with mapping options.  We use ArcGIS software for final map productions
>
> and analysis.
>
>
>
> I am not very clued up on these aspects so any advise would be greatly
>
> appreciated.
>
>
>
> Many thanks in advance,
>
> Taryn
>
>
>
>
>
> ________________________________
>
> Research Associate - Botany Department
>
> Nelson Mandela Metropolitan University
>
> P.O. Box 77000
>
> Port Elizabeth
>
> 6070
>
>
>
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>
>
>
> --
>
> Gerhardus Geldenhuis
>
>
>
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