I'm working on a project with a few publicly available datasets. One of them is from the USGS, it's their prediction of peak ground acceleration in 50 years. Here's a link, and here's what it looks like loaded into QGIS:

enter image description here

The problem is that the "coordinates" of San Diego, California are (roughly) -1,700,000 by 3,000,000.

The real data I'm working with is stored in SQL Geography, in a SQL Server, with SRID 4328 matched up real-world latitude and longitude.

My question is, especially since I've seen a lot of this type of who-knows-geometry going on, how do I mesh up geography with weird geometry? I'm using OGR2OGR to convert from shapefiles, in this case.

  • It's unlikely the USGS wouldn't say what projection was being used. If you edit the question to add a link to the data, or include the projection file (.prj) content, it will be easier to help you. – Vince Sep 25 '14 at 17:08
  • @Vince link added in the question, and here for reference: earthquake.usgs.gov/hazards/products/conterminous – Eric Sep 25 '14 at 17:50
  • @Vince in this question ( gis.stackexchange.com/questions/30613/… ) it's stated that QGIS will read the .prj file automatically when it loads the shapefile. It's in the right directory, I'm looking at it with notepad open. So now I have the projection, but curious why QGIS didn't set it up that way from the beginning and went with project defaults. – Eric Sep 25 '14 at 17:59

That data appears to be in the following coordinate system based on the files I found here.

You need to reproject/transform all of your data to be in the same coordinate system, whether it be on the fly in GIS software, or permanently in the data itself.


Authority: Custom

Projection: Albers, False_Easting: 0.0, False_Northing: 0.0, Central_Meridian: -95.0, Standard_Parallel_1: 29.5, Standard_Parallel_2: 45.5, Latitude_Of_Origin: 0.0, Linear Unit: Meter (1.0)

Geographic Coordinate System: GCS_Clarke_1866

Angular Unit: Degree (0.0174532925199433), Prime Meridian: Greenwich (0.0), Datum: D_Clarke_1866, Spheroid: Clarke_1866, Semimajor Axis: 6378206.4, Semiminor Axis: 6356583.799998981, Inverse Flattening: 294.9786982

  • thanks, I think you've got me on the right track. I'm in QGIS trying to set the projection for the layer but can't seem to find the one referenced there. – Eric Sep 25 '14 at 17:51
  • The definition is not in EPSG nor it is an Esri one. – mkennedy Sep 25 '14 at 19:53
  • Why the USGS is distributing data using the Clarke 1866 datum is beyond me... I understand using the Albers projection, but not sure why they couldn't use the NAD83 or WGS84 datums to be consistent with most other data sources. – jmpreiks Sep 25 '14 at 22:11

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