I am a complete novice.

I have the following .prj file:


I need to get the EPSG code for this, but when I try http://prj2epsg.org/search I keep getting the following error

Recursive call while creating a 'HTTP_AuthorityFactory' object.

I have searched all over, but cannot figure this out. I have tried http://spatialreference.org/ and found http://spatialreference.org/ref/sr-org/7149/ which I think is the same .prj file, but 7149 is not a valid SRID according to PostGIS.

  • 2
    It's not a known EPSG (nor Esri) definition. You would have to put it in as a custom definition.
    – mkennedy
    Aug 31 '16 at 19:32
  • @mkennedy: If I do that, how do I know what the proj4 string format is for this?
    – Ask613
    Aug 31 '16 at 19:57
  • 1
    Simply run gdalsrsinfo on the .prj file.
    – AndreJ
    Sep 1 '16 at 6:21

EPSG and SRID are not the same thing. SRID is a tag identifier for Spatial Referencing Systems. The EPSG Geodetic Registry is a set of SRIDs created by the European Petroleum Survey Group. It's been around for quite a while, and encompasses many of the most widely used SRS', so it kind of became an informal industry standard, but it's but no means the only one. ESRI, for one, has its own SRID set. The biggest authority in it is probably SpatialReference.org, which you have already visited.

Many GIS softwares accept different combinations of SRID sets. QGIS accepts many types, whereas PostGIS only accepts EPSG (and not even the entire set, but a subset of about 5000 codes as of version 2.2.0). Your projection does not seem to be part of EPSG (you can search for EPSG projections at their website), so you won't be able to just use a code (in fact, the code you found on SR.org for your projection means an entirely different SRS in EPSG).

However, PostGIS lets you define your own SRS, and give it a custom SRID, which you'll then be able to use in your queries from then on (it's basically an insert in the spatial_ref_sys table, which all PostGIS-enabled DBs have). For how to set your own SRID, check this answer to a previously asked question.

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