[OSGeo Africa] Field mapping GPS suggestions please

Wed May 20 05:46:25 PDT 2015

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<mailto: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.

[cid:image62f91a.JPG at 573859a2.46a4fbae]

From: africa-bounces at lists.osgeo.org<mailto:africa-bounces at lists.osgeo.org> [mailto: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<mailto: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<http://www.mapland.co.za>

+27 (0)82 567 9322<tel:%2B27%20%280%2982%20567%209322>

On 20 May 2015 at 10:27, Gerhardus Geldenhuis

<gerhardus.geldenhuis at gmail.com><mailto: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><mailto: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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