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I would like to use QGIS to convert a CSV file from UTM to lat/long.

I imported the CSV file with the "Add Delimited Text Layer" plugin. This works fine, the data looks like it is projected properly on my map.

However, when I try Layer> Save as... and set the Selected CRS to NAD83, it does not convert my UTMs to lat/long. When I go Open Attribute Table, the x and y coordinates are still in meters, not degrees.

Any thoughts why this isn't working for me?

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1 Answer

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Reprojecting changes the geometries. It does not change any values in the attribute table. It never does. For the GIS, fields named x and y have no special meaning.

You can recalculate the values in the attribute table after the reprojection step using field calculator.

  1. Load the CSV in UTM
  2. "Save as ..." to reproject to NAD83
  3. Use Vector - "Add geometry columns" to add lat/lon values to the attribute table or use field calculator to update the existing x and y fields (the operators are $x and $y)
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Thanks for the answer, that would explain why it didn't work. I thought that QGIS would know which fields are x and y values, you have to select the X field and the Y field before you can import the data. How would I use QGIS to convert UTMs to lat/longs? I can't see anything in the field calculator for reprojecting. – Stu Jan 29 at 8:22
There are menu commands for reprojection of vector layers and for raster layers. But reprojecting (changing the underlying data) is a more sophisticated (although simple) action than viewing the data in a new projection, which QGIS does on the fly. – Willy Jan 29 at 9:16
@Stu: Sorry now I'm confused. You already said correctly that you reproject using Layer > Save as. – underdark♦ Jan 29 at 11:34
I have a CSV file that has my x and y coordinates as UTMs. I would like to convert the coordinates to lat/long. I understand how to view the data in whatever projection I want, but I would like to actually change the underlying data. I would like to change my CSV file so that it has lat/long instead of UTMs. – Stu Jan 29 at 21:23
I thought that I could do this by using Layer > Save As and changing the Selected CRS to NAD83, but when I go to the Attribute Table of the new file to get the reprojected x/y coordinates, they are still UTMs. – Stu Jan 29 at 21:27
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