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I have close to zero GIS background.

My goal is to extract only a certain UTM zone of this land use tiff file. I only know how to do that via specifying lat lon clipper box, however right now Qgis only shows things in pixel coordinate. Is there any way I can:

i. change project coordinates to lat/lon, or ii. extract UTM zone straight from the current one (meters from origin @ 45N100W)?


The docs show the projection as Lambert Azimuthal Equal Area Central Meridian -100.0, Lat of Origin 45.0 which to my knowledge corresponds to US National Atlas Equal AREA EPSG:2163

I've tried setting both layer and project CRS to the mentioned projection, but no avail.

Here's a screenshot + first bit of gdalinfo.

enter image description here

Size is 37000, 35000
Coordinate System is:
PROJCS["Sphere_ARC_INFO_Lambert_Azimuthal_Equal_Area",
    GEOGCS["Sphere_of_Radius_6370997m",
        DATUM["Sphere_of_Radius_6370997m",
            SPHEROID["Sphere of Radius 6370997m",6370997,0]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433]],
    PROJECTION["Lambert_Azimuthal_Equal_Area"],
    PARAMETER["latitude_of_center",45],
    PARAMETER["longitude_of_center",-100],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["meters",1]]
Origin = (-4418000.000000000000000,4876500.000000000000000)
Pixel Size = (250.000000000000000,-250.000000000000000)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_RESOLUTIONUNIT=1 (unitless)
  TIFFTAG_SOFTWARE=IMAGINE TIFF Support
Copyright 1991 - 1999 by ERDAS, Inc. All Rights Reserved
@(#)$RCSfile: etif.c $ $Revision: 1.10.1.9.1.9.2.11 $ $Date: 2004/09/15 18:42:01EDT $
  TIFFTAG_XRESOLUTION=1
  TIFFTAG_YRESOLUTION=1
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (-4418000.000, 4876500.000) 
Lower Left  (-4418000.000,-3873500.000) 
Upper Right ( 4832000.000, 4876500.000) 
Lower Right ( 4832000.000,-3873500.000) 
Center      (  207000.000,  501500.000) 
  • 1
    Pixels are 250 metres... this is an odd SRS, not that I'm familiar will North American projections. I can see it's confusing but where is the problem? If you load other data does it align to where you'd expect or off the page? – Michael Stimson Jun 13 '16 at 23:26
  • sry, editted post to make things more clear. I need to extract an UTM zone, but I don't know how to do that without using lat/lon. Is there a way to display the coordinates to lat/lon as opposed to pixels? – M. F Jun 14 '16 at 17:19
  • 1
    These coordinates are not pixels, but meters from the origin of the projection. You might want the UTM zone boundaries shapefile from earth-info.nga.mil/GandG/coordsys/grids/… and clip your raster to the UTM zone you need. And you need to reproject your raster to WGS84, or the shapefile to the rasters CRS. – AndreJ Jun 14 '16 at 17:28
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If you want to change the CRS of the raster, use Raster -> Projections -> Warp(Reproject), choosing a different filename and WGS84 EPSG:4326 as target SRS.

DO NOT use Set Layer CRS for this task, it will corrupt your data.

To avoid future mistakes, remove the original layer from the canvas, and set the project CRS to WGS84 as well.

With the raster now in lat/lon, you can clip it to the degree bounds of the UTM zone you need.

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