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I'm very new to QGIS, and I have a sample GeoTIFF (and corresponding TFW) file(s) that I'm trying to determine what the longitude and latitude coordinates for each of the 4 corners of the image are - coordinates of 2 opposite corners of the image would also be okay.

I'm able to import the GeoTIFF as a raster layer in QGIS, but I noticed that all the coordinates that are displayed are in UTM format. In the metadata, I see the layer extent, which I was told are the UTM coordinates of the bottom-left and top-right of the corners of the image (square-shaped), which I can work with. However, I have to determine what the UTM zone is so I can use that along with the UTM coordinates in the metadata to convert the points to latitude and longitude.

This seems like a fairly simple task, but I'm unable to find out what the zone is of the image to move forward with the UTM to long/lat conversion.

  • Do you know where the images are located in this world? In which country? – ahmadhanb Oct 6 '16 at 1:20
  • I find the simple way is to set Google Earth to display UTM coordinates (Tools -> Options) and then fly to a town or other feature that appears on the raster image. The UTM coordinates for the location under the GE pointer appear in the bottom bar, including the UTM zone. This usually works, but with UTM zones there can be a fair amount of overlap, in the event of problems try the UTM zones on each side of the one reported by GE. – nhopton Oct 6 '16 at 8:43
  • These are sample GeoTIFFs so I have no context on the location of these images. All I know is the extent (UTM coordinates for the bottom-left and top-right of the image), but no idea what the UTM zone is. It sounds like I'm stuck and unable to convert to lat/long without knowing the zone, which I can't find in the metadata. – Dexter J. Oct 6 '16 at 14:47
  • In the metadata, however, I do have the layer spatial reference system defined as: +proj=lcc +lat_1=53.83333333333334 +lat_2=51.83333333333334 +lat_0=51 +lon_0=-176 +x_0=1000000 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs - can this help? – Dexter J. Oct 6 '16 at 15:21
  • @AndreJ my question is different from the one you pointed out to. That one talks about calculating the UTM zone once you have the lat/long. In this case all I have is the UTM coordinates and I want to convert to lat/long without knowing the UTM zone. – Dexter J. Oct 6 '16 at 16:36
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If you enter the metadata proj string in Google search, you end up at http://spatialreference.org/ref/epsg/3477/proj4/ or NAD83(NSRS2007) / Alaska zone 10. EPSG:26940 is basically the same.

So it has nothing to do with UTM, rather state plane coordinate systems

  • Because I know the image, I know it's not in Alaska. The extent in the image metadata has the following UTM coordinates: 256587.2038488080142997,2708590.4406288559548557 : 258556.4038783459982369,2710614.4406592161394656 (no UTM zone defined) – Dexter J. Oct 6 '16 at 18:39
  • Can you add the full metadata of the image to your question? Or upload the file somewhere if allowed? – AndreJ Oct 7 '16 at 5:46
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I was able to determine the UTM zone by importing a UTM shapefile that I found into the QGIS project as a vector layer, as well as the image (GeoTIFF) I was working with. I then located the image that was overlayed on top of the UTM shapefile to see which zone it was located in. I used the info tool (identify features button on the toolbar) in QGIS to select the the zone the image was in, and the zone number is listed in the properties/infobox.

Once I had that, I used this utility (http://www.rcn.montana.edu/resources/converter.aspx) to convert the UTM coordinates (with zone) to determine the latitude and longitude.

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