[GRASS-user] Which EPSG code for location default?

[Jeff McKenna]

Hi Rich,

Taking a look at your output, my brain said "good question", ha.

Usually the key line to look for is the "AUTHORITY:" line, which yours 
lacks.

So the usual next step is to start searching on https://epsg.io for the 
text "UTM zone 10N".

But more recently the official EPSG homepage includes a search tool that 
does a live search on its own database (giving guaranteed 
accurate/uptodate responses):

- goto https://epsg.org
- click the top menu: EPSG Dataset/Text Search
- enter: UTM zone 10N and press "Go"
- gives a response of 12 items

EPSG:26910 does look somewhat similar :)

Hope that gives you some hints... (at least on the official EPSG code 
perspective)

-jeff




-- 
Jeff McKenna
GatewayGeo: Developers of MS4W, MapServer Consulting and Training
co-founder of FOSS4G
http://gatewaygeo.com/




On 2021-09-22 7:49 p.m., Rich Shepard wrote:
> Applying gdalsrsinfo to a shapefile's .prj produced these results:
> 
> PROJ.4 : +proj=utm +zone=10 +datum=NAD83 +units=m +vunits=m +no_defs
> 
> OGC WKT2:2018 :
> COMPOUNDCRS["NAD83 / UTM zone 10N + NAVD88 height",
>      PROJCRS["NAD83 / UTM zone 10N",
>          BASEGEOGCRS["NAD83",
>              DATUM["North American Datum 1983",
>                  ELLIPSOID["GRS 1980",6378137,298.257222101,
>                      LENGTHUNIT["metre",1]],
>                  ID["EPSG",6269]],
>              PRIMEM["Greenwich",0,
>                  ANGLEUNIT["Degree",0.0174532925199433]]],
>          CONVERSION["UTM zone 10N",
>              METHOD["Transverse Mercator",
>                  ID["EPSG",9807]],
>              PARAMETER["Latitude of natural origin",0,
>                  ANGLEUNIT["Degree",0.0174532925199433],
>                  ID["EPSG",8801]],
>              PARAMETER["Longitude of natural origin",-123,
>                  ANGLEUNIT["Degree",0.0174532925199433],
>                  ID["EPSG",8802]],
>              PARAMETER["Scale factor at natural origin",0.9996,
>                  SCALEUNIT["unity",1],
>                  ID["EPSG",8805]],
>              PARAMETER["False easting",500000,
>                  LENGTHUNIT["metre",1],
>                  ID["EPSG",8806]],
>              PARAMETER["False northing",0,
>                  LENGTHUNIT["metre",1],
>                  ID["EPSG",8807]],
>              ID["EPSG",16010]],
>          CS[Cartesian,2],
>              AXIS["(E)",east,
>                  ORDER[1],
>                  LENGTHUNIT["metre",1,
>                      ID["EPSG",9001]]],
>              AXIS["(N)",north,
>                  ORDER[2],
>                  LENGTHUNIT["metre",1,
>                      ID["EPSG",9001]]]],
>      VERTCRS["NAVD88 height",
>          VDATUM["North American Vertical Datum 1988"],
>          CS[vertical,1],
>              AXIS["gravity-related height (H)",up,
>                  LENGTHUNIT["metre",1,
>                      ID["EPSG",9001]]]]]
> 
> The data are the Columbia River and southern Washington state.
> 
> It's been a couple of decades since I last dug into proj and I'd appreciate
> being pointed to a document that will teach me which of the several EPSG
> codes above is the one to which I want to apply to PROJ_INFO in the
> PERMANENT mapset.
> 
> TIA,
> 
> Rich
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