Problem displaying GPS data Re: [Qgis-user] From Bob Peck who needs help

[Alex Mandel]

On 12/16/2011 05:00 PM, Ramon Andiñach wrote:
> 
> On 17/12/2011, at 01:44 , Robert Peck wrote:
> 
>> Hello,
>>  
>> Uncle!  I need help.
>>  
>> I have been trying to learn QuantumGIS so that I can put GPS (NAD 83 datum) locations of rock outcrops on a USGS quadrangle topographic map (NAD 27 datum), connect the points to make contours, and produce a geological map of the quadrangle.  I know how to make an Excel file into a .csv file which I can use to import the data to the project.  I have learned how to open a new project, load a topo quad map, load a data set, and make either one of them visible on the map panel, and that's as far as I get.  I'm trying to get the data points to appear on the map but am having no success.  Below are the steps I've taken to get that far.
>>  
>> Any suggestions as to what I'm doing wrong or what I'm not doing right?  Any assistance will be gratefully appreciated.  Thank you, Pilgrim
>>  
>> 1.  Open QGIS.
>> 2.  File  >>  New Project.
>> 3.  Layer  >>  Add Raster Layer  >>  Browse  >>  Hinton_UTM27z17_nocoll_grey400dpi.tiff  >>  Open.
>> 4.  The Hinton,WV USGS quadrangle map appears in the map panel.
>> 5.  Settings  >>  Project Properties.
>>             a.  Enable 'on the fly' CRS transformation.
>>             b.  Set CRS to NAD 27/UTM zone 17N (ID 2146).
>>             c.  Hit "apply" and then "OK".
>> 6.  The map disappears.
>> 7.  Right click on the Hinton quad layer in the left panel   >>  Set layer CRS  >>  Set CRS to NAD 27/UTM zone 17N  (ID 2146)  >>  hit "OK".
>> 8.  The map reappears.
>> 9.  Layer  >>  Add delimited text layer  >>  browse   >>  NRGGPSHINTONAVIS.csv  >>  Open.
>> 10.  "Create a layer from a delimited text file" dialog box opens.
>> 11.  I made sure that "selected delimiters" and "comma" boxes were both checked.
>> 12.  I set X to UTME and Y to UTMN  >>  hit "OK".
>> 13.  No data points appear.
>> 14.  Right click on the data layer  >>  set layer CRS  >>  set CRS to NAD 83/UTM zone 17N (ID 2294).
>> 15.  View  >>  zoom to layer  >>  data appear but no map.
>> 16.  If I choose the map layer and go to View  >>  zoom to layer  >>  the map appears but no data.  This goes back and forth with no data points appearing on the map, even when the map layer is the bottom layer in the layer panel.
> 
> Hi Bob,
> 
> I have a suggestion. I'm not saying that I definitely have the answer.
> 
> The bit of information that we'll need here is how you made the csv file (or maybe a look at the first few rows of the csv file).
> 
> If you copied the waypoints down manually, then that's probably the right path, and I'd suggest checking your numbers.
> 
> But, if you downloaded the data from the GPS, then the data is probably not in NAD 83.
> On all of the GPS units I've used, they only display points in the datum you select. Really they store them in another datum, typically WGS84 (lat-long, and not projected). You should be able to confirm this by looking in the csv file (WGS84 would be a small number with lots of decimals, NAD would be a big number with few decimals).
> 
> And a suggestion to finish with. Try and use an informative subject line "Help!" doesn't give me any idea if it's something I can help with, but "problem displaying GPS data" is something I might be able to help with (or at least make a suggestion :) 
> 
> -ramon.
> 

Yes, I agree if you copied the data via cable from the GPS it is most
likely WGS84 Lat/Lon EPSG:4326

However, note that NAD 83 is only a datum, not a coordinate system. If
the data was written down by hand on a unit set to display UTM Zone
whatever NAD 83 then the statement in the prior email would be correct.
If the unit was set to Lat/Lan NAD 83 then it's would actually look the
same and only be off by a few meters.

So yes, verify what you actually have in your csv. If you're still
having trouble I'd be happy to convert it to a shp or gml file for you,
and make a quick tutorial video (hmm look online there might be one).

Thanks,
Alex