GPS data not lining up with our basemap

[MiguelGarcia]

Using ArcGIS for Windows Mobile on Trimble's GeoExplorer 6000 Series handheld. The data we capture does not line up with our
basemap which is in NAD83 State Plane Zone 2, Lambert Conformal Conic Projection. It appears that the unit defaults to capturing data in WGS84 Datum. Is there workaround for capturing GPS coordinates to conform with our GCS and Projection?

[TimDonoyou]

Hi there,

We have had the same problem with Ashtech Mobile Mapper 10s converting from WGS84 to British National Grid.

I have submitted a support call but this has not been resolved yet but I received the following reponse:

I believe that, when using the out of the box functionality, ArcGIS for Windows Mobile will automatically reproject your GPS locations based on your map�??s coordinate system. So, if your points are misaligned, it�??s not likely to be because the GPS locations are incorrectly projected.

Please see the following web page and scroll down to the, �??GPS display on the map�?� section.

Using GPS in Windows Mobile devices - http://resources.arcgis.com/en/help/windows-mobile/app/index.html#//007v0000002t000000



If you were developing an application using the ArcGIS Runtime SDK for Windows Mobile, you can define the transformation using the SpatialReference class. You can read about this further on the following web help page. Scroll to the paragraph beginning, �??The most likely situation where you will need to work with projections is when your map is published in a projected coordinate system and you want to plot GPS position�?�.

Spatial references in ArcGIS for Windows Mobile - http://resources.arcgis.com/en/help/windows-mobile-sdk/concepts/index.html#//01sp0000003v000000



When you say that the points and polygons that you have collected using GPS are misaligned, by what distance are the features misaligned? The misalignment may not be because of any transformation issue but may instead be the result of inaccuracy of your GPS receiver. GPS data collection is not always highly accurate. Often, positions are only accurate to about 15 metres. The following web page explains the reasons for this. Scroll down to �??Accuracy and error sources�?�.

Global Positioning System - http://wiki.gis.com/wiki/index.php/GPS



Esri have very recently released a solution for high accuracy GPS data collection, however this is only compatible with selected Trimble devices.

Please see:

High Accuracy GPS now available with ArcGIS for Windows Mobile - http://blogs.esri.com/esri/arcgis/2012/10/04/high-accuracy-gps-now-available-with-arcgis-for-windows...

This may or may not help - please let us know if you come up with a solution.

Cheers

Tim