How do you change GPS datum on EoTopo

Try:
Settings>
General settings>
Position display format

Will use WGS84 or GDA94 - wouldn't expect any maps to still be AGD66.
100M is not an issue, and is to be expected in some locations.
Which particular map and map scale do you have this error?
Never been a fan of the Samsung GPS chipset.
Switching OFF A-GPS can in fact give you better accuracy at times.
GPS Test from the Google Play Store is a good free App to test your GPS accuracy.
https://play.google.com/store/apps/details?id=com.android.gpstest

Thanks for the advice. These settings only change the way degrees minutes seconds is displayed.

Used three GPS units (Samsung S8, Hema HN7 and an old Garmin). The Hema and Garmin were set to WGS 84, do not know what the S8 datum is. I then went onto Google Earth and got there GPS reading for the same location. The Hema and Garmin where within 5 metres, but the S8 was at least 100 metres out.

Hello - your post is somewhat ambiguous. Do you mean the coordinate readout doesn't match what you expect/know to be the correct coordinates or that the position of the pointer displayed on the screen doesn't match a point on the underlying map?

If you are using EoTopo keep in mind it is a small scale map (most data based on 250K map data from Geoscience Australia) so what you see is not super accurate e.g some roads are shown as lines several hundred metres wide and some are offset to allow for plotting nearby features (e.g rail lines paralleling roads)

I suspect the issue is the map you are using and not the device or settings....but some more info would help establish what your issue is in the first place.

Cheers
Greg

Hi Allan, are you referring to Places shown on map?

Places data is managed separately to the EOTopo map data and is updateable live.

There are 90,000 POIs in the Places database and some old "Places" are data that was recorded using older technology/less accurate than todays technology but the good news is that our Places database is live so can be updated immediately. And because these Places are used as " Overlays" in the map it means everyone can get updates on demand via the ExplorOz Traveller app so their Places overlays are updated free.

If you can use our system tools please to alert us to each Place that you stumble across that needs a slight shift...we can action within 24 hrs.

You can use the system (app or website) to create a new place at the correct spot and put a comment in the old.

Allan,

I am very interested in your findings and as the app developer and map producer would like to be sure of exactly what we are talking about. Are you out and about looking at things or using Satellite images in the app or something else related to your noted differences.

You mention datum adjustment on EOTopo but are you using the ExplorOz Traveller App or some other mapping program on your device? The Raster map sheets are set to WGS84 via EPSG:4326 so if using OziExplorer or some other app on your phone set the datum to this (though I have configured this default in the OziExplorer .map files we send out with the Raster product). The online maps and ExplorOz Traveller App use EPSG:3857 to align them with the web/online accepted datum Spherical Mercator. This allows us to shift between online map sources without difference. The web site and ExplorOz Traveller App do not give you a datum adjustment option as they are locked to the production datum.

As mentioned by several people certain devices behave in different ways and AGPS/GPS/GLOSNASS, power management, cell tower triangulation, wifi detection and a wealth of other technologies can mess things up. But it is important to me that we identify any possible data errors to get a plan of action to check/remedy any potential issues. Can you point me at some of the places you have noted and is it the places layer shown on the app or was it a feature drawn on the underlying map data that was different.

As mentioned by Michelle above there are two sets of data at play in the app, one being the base map EOTopo and the other POI dataset being Places shown with the markers. These two layers are melded together during EOTopo updates so it is vital to us that we are sure we have the best Places data layer before we start on the next round of EOTopo updates though we do not use all Places data in the map production as a great number of Places elements are not needed on the Topo product.

Anyway if you can let us know we can work with you to identify what is going on, best to connect with us using the Help Desk as this allows us to manage it and track the issue to completion.

David

Hi David and Michelle
I am not referring to Places on EoTopo.
I did a GPS test with the three GPS units (Hema HN7, an old Garmin both set to WGS84 datum and Samsung S8 (do not know what datum it uses) with the latest EoTopo maps. I used the middle of our 10 hectare property in the hills and took a reading from all three GPS units. This position is easily visible on Google Earth. The Hema and Garmin were within 5 metres, but the Samsung S8 with EoTopo app gave a different reading which is about 100 metres to the SW.
My wife and I are bird watches and all of our Australian bird sightings are entered into eBird. Within this program you enter your bird sightings and GPS coordinates which then takes you to a map that can be either satellite or what looks like Google maps. This is we have found the Samsung S8 out. When travelling we use the car based Hema HN7 GPS readings for our locations. But when we walk away from the vehicle the offline EoTopo maps are used, but give us incorrect location readings.
The problem may well be the Samsung S8 having a different datum, but I do not know what datum they use.
Hope this helps

Michelle
I am using DMS format.
I have just taken a GPS reading with the Hema HN7 and EoTopo on the Samsung S8. There is only 0.4 of a second difference between the two. Thats very good. Don't know what the issue was the other day.
Apologies for wasting your time.
Thanks to you and your team for their thoroughness in trying to solve my problem. And. To others that came in on the conversation.
Cheers
Allan