[Proj] Using cs2cs to convert UTM/NAD27 to latlong/WGS84

Eric Miller EMiller at dfg.ca.gov
Fri Oct 1 12:24:46 EDT 2004

I would convert to NAD83 using nadgrids=conus (to exclude interference
from other grids).  Then, just take it on faith that NAD83 is close
enough to WGS84.

$ cs2cs -E +proj=utm +zone=11 +datum=NAD27 +nadgrids=conus +to
+proj=latlong +datum=NAD83
0300917 4502746
0300917 4502746 119d21'20.664"W 40d39'12.176"N 0.000

This result is nearly the same as what I get from GEOTRANS (to WGS84
using different datum transform method).

I didn't check the accuracy of your UTM coordinates for the stated

Eric G. Miller
GIS Analyst
Wildlife and Habitat Data Analysis Branch
Department of Fish and Game

>>> Carl Reisinger <carl_reisinger at sbcglobal.net> 9/30/2004 7:07:55 PM
I have downloaded and built the proj-4.4.8 sources (also downloaded and
into the nad directory prog-nad27-1.1.tar.gz before the build).
The build system is FreeBSD 4.9 running gcc version 2.95.4.

I am now trying to convert a series of coordinates that are in UTM and
based on
the NAD27 datum into latlong/WGS84.

I have been unable to get any result out of cs2cs. Example output with
environment variable PROJ_DEBUG defined:

$ sh -x example
+ cs2cs -E +proj=utm +datum=NAD27 +to +proj=latlong +datum=WGS84 -v
pj_open_lib(proj_def.dat): call
fopen(/usr/local/share/proj/proj_def.dat) -
pj_open_lib(proj_def.dat): call
fopen(/usr/local/share/proj/proj_def.dat) -
# ---- From Coordinate System ----
#Universal Transverse Mercator (UTM)
#       Cyl, Sph
#       zone= south
# +proj=utm +datum=NAD27 +ellps=clrk66
# +nadgrids=@conus, at alaska, at ntv2_0.gsb, at ntv1_can.dat 
# ---- To Coordinate System ----
#Lat/long (Geodetic)
# +proj=latlong +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
pj_open_lib(conus): call fopen(/usr/local/share/proj/conus) -
Ctable Conterminous United States 273x121: LL=(-131,20)
pj_open_lib(alaska): call fopen(/usr/local/share/proj/alaska) -
Ctable Alaska 529x249: LL=(-194,46) UR=(-127.875,77.125)
pj_open_lib(ntv2_0.gsb): call fopen(/usr/local/share/proj/ntv2_0.gsb) -
pj_open_lib(ntv1_can.dat): call
fopen(/usr/local/share/proj/ntv1_can.dat) -
NTv1 393x177: LL=(-142,40) UR=(-44,84)
pj_apply_gridshift(): failed to find a grid shift table for
                      location (-5.3547203dW,40.6534808dN)
   tried: @conus, at alaska, at ntv2_0.gsb, at ntv1_can.dat 
0300917 4502746 11      *       * 11.000

The location is Gerlach, NV if that matters at all.

Punting on cs2cs and using nad2nad, I get:

+ nad2nad -i utm=11,27 -o 83 -r conus
pj_open_lib(conus): call fopen(/usr/local/share/proj/conus) -
119d21'20.664"W 40d39'12.176"N

Now, I really don't know if that answer is correct but comparing it to
obtained from jeeep.com, it is different.

I would like to see the cs2cs work. Is there anything obvious in the
output that
I need to address?

Failing that, is the results from the nad2nad to be trusted?

Carl Reisinger

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