[GRASS-user] cs2cs Command Syntax Check

[Tom Russo]

On Mon, Feb 27, 2012 at 03:23:55PM -0800, we recorded a bogon-computron collision of the <rshepard at appl-ecosys.com> flavor, containing:
>    I have many lon-lat coordinates in decimal degree format that are to be
> converted to spcs Nevada East Zone (FIPS: 2701, ADS: 4601, UTM Zone 11),
> NAD83, US survey feet or, as the PROJ_INFO in that location has it:
> 
> name: Transverse Mercator
> proj: tmerc
> datum: nad83
> ellps: grs80
> lat_0: 34.75
> lon_0: -115.5833333333333
> k: 0.9999
> x_0: 200000.00001016
> y_0: 8000000.000010163
> no_defs: defined
> 
>    The command I propose to use is:
> 
> cs2cs +proj=latlong +datum=NAD83 +to +proj=utm +zone=11 +datum=NAD83
> 
>    Is this correct?

No.  Nevada East Zone State Plane Coordinate System is not the same as 
UTM, Zone 11 (even though it may lie in UTM zone 11).   Your command line will 
return UTM coordinates in meters easting and northing, not SPCS coordinates in 
US survey feet.

What you want is to tell cs2cs to use the EPSG number 3421
as the target coordinate system.   From the PROJ.4 epsg file, that means:

# NAD83 / Nevada East (ft US)
<3421> +proj=tmerc +lat_0=34.75 +lon_0=-115.5833333333333 +k=0.9999 +x_0=200000.00001016 +y_0=8000000.000010163 +ellps=GRS80 +datum=NAD83 +units=us-ft +no_defs  <>

which you can see matches your PROJ_INFO information.

(On my system, the EPSG database for PROJ.4 is in /usr/local/share/proj/epsg)

You should use this command line instead:

cs2cs +proj=latlong +datum=NAD83 +to +init=epsg:3421



-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick