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Importing GPS points

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#1
GrannyNerd

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I have downloaded some waypoints from a GPS, imported the table as XY Data and exported to a layer file, but I cannot get the points to plot where they should. Infact, they plot several hundred miles to the south!
I tried importing the waypoints from the GPS in several different projections appropriate for my area (NAD'83 Zone 9, WGS_1984, GCS_NA_1983) but they all plot in the same area. I tried bringing the table in using the XY tool in Data Management, Tables. Still no luck. The lat and long values in the table downloaded from the GPS are correct.
I cannot imagine what I am doing wrong. Any ideas out there? :(

#2
David Medeiros

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I have downloaded some waypoints from a GPS, imported the table as XY Data and exported to a layer file, but I cannot get the points to plot where they should. Infact, they plot several hundred miles to the south!
I tried importing the waypoints from the GPS in several different projections appropriate for my area (NAD'83 Zone 9, WGS_1984, GCS_NA_1983) but they all plot in the same area. I tried bringing the table in using the XY tool in Data Management, Tables. Still no luck. The lat and long values in the table downloaded from the GPS are correct.
I cannot imagine what I am doing wrong. Any ideas out there? :(


The point table needs to be imported as whatever coordinate system the GPS was set to on export, not what you want it to be in the map. Be sure to get the datum as well. Since you see lat/long in the table than that is what they should be imported as.

If you continue to have point misplacement double check that the coordinates are exporting as decimal degrees instead of degree, minutes, seconds and that the numbers for either W or S hemisphere coordinates have a negative value.

GIS Reference and Instruction Specialist, Stanford Geospatial Center.

 

www.mapbliss.com

 


#3
P.Raposo

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Agreeing with David - check the coordinate system (i.e., datum and projection) that the GPS unit is set to record/export in. The default usually is, I think, geographic coordinates (lat and long) using the WGS 1984 datum, since that's what the GPS system is based on.

Not sure what software you're using, but I often do this in ArcMap. I bring the table itself into ArcMap, usually as an Excel or CSV file. Then, in ArcMap, right-clicking the table from the table of contents you can plot x,y values. In that process, just be sure to assign the same coordinate system to that plotting as your unit is recording/exporting in. You'll get an "events" layer in your map document that you then probably want to export to a proper shapefile or geodatabase feature class.

Also, in case this is just one of those things that seems too silly to consider, make sure negative signs are in your coordinate values where appropriate :)

Hope that's helpful somewhere along your process!




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