I used QGIS to find the extents/bounding boxes of a list of features from census data.

I used the following method: Vector - Research tools - Polygon From Layer Extent, which creates a new shapefile with a table of extent values for each feature.

However, the resulting extent values (minx, miny, etc.) are not LAT/LONG. I'm not sure what they are. The properties show CRS as "USER:100000 - Generated CRS (+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=37.5 +lon_0=-96 +x_0=0" even though I set the project default to WGS 84 EPSG: 4326. If I change it back to WGS84, the data stays to same.

What CRS format are QGIS extents and how can I convert them to standard Lat/long so that I can plot them?


1 Answer 1


Extents are computed in the native projection of the data. If you want "standard lat/lon" I believe that the easiest way is to re-project your source data physically into EPSG:4326 and compute extents from the projected file.

  • That's the problem, the source data is EPSG:4326. Everything, by defualt, is EPSG:4326, except the resulting extents, for some reason. Sep 19, 2014 at 8:27
  • I used this for testing, could you repeat nacis.org/naturalearth/10m/cultural/…
    – user30184
    Sep 19, 2014 at 8:30
  • Thanks, but the link appears to be broken. Is there a way to compute the lat/long using the current CRS? I'm using a Google Maps API. Perhaps I can add code that computes the Lat/Long using the generated CRS? Sep 19, 2014 at 8:43
  • 1
    The link seems to be now naturalearthdata.com/http//www.naturalearthdata.com/download/…. But do not start fixing anything before knowing what is broken. QGIS believes your data is in user projection, you believe it is in EPSG:4326 and you must find the reason. What does ogrinfo tell about the projection? Have you played with custom projections docs.qgis.org/2.0/en/docs/user_manual/working_with_projections/…?
    – user30184
    Sep 19, 2014 at 9:11
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    Have a look at the .prj parts of your shapefiles. They define the projection and there you can read PROJCS["USA_Contiguous_Albers_Equal_Area_Conic",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Albers"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-96.0],PARAMETER["Standard_Parallel_1",29.5],PARAMETER["Standard_Parallel_2",45.5],PARAMETER["Latitude_Of_Origin",37.5],UNIT["Meter",1.0]]. Reproject your data to 4326.
    – user30184
    Sep 20, 2014 at 8:08

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