Is there a package available to convert FROM UTM to
latitude/longitude?  We're trying to convert archaeological
site locations to a format required by the administrative
agency overseeing the work (not a U.S. agency).

Any help appreciated.

Alex Barker
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Alex W. Barker                   BITNET: USERLJPD@UMICHUM
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re:  Converting UTMs to Lat/Long?

Alex et al.:

One solution might be to consider "The Geographic Calculator" from
Resolution Mapping, Inc., River Road, P.O. Box 718, Newcastle, ME
04553. (207) 563-2311. The GC is a Microsoft Windows application that
enables conversion to-from Lat/Long, State Plane, UTM, Landsat WRS,
user defined coordinate and other systems. It sells for $225. This is
a solution if you don't have somehting like Arc/Info, in which these
CONVERTsions are standard fare.

Good luck. DLC.
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In <23553...@UMICHUM.BITNET> Alex Barker <USERL...@UMICHUM.BITNET> writes:
  One method for converting between UTM coordinates and
  latitude/longitude values is to utilize the General Cartographic
  Transformation Package (GCTP, Version 2), available from the
  National Geodetic Survey, NOAA.

  GCTP is a VS/FORTRAN callable set of entry points which can be used
  to convert between any two of the following 20 map projections
  (forward and inverse transformations).  Note that projections
  to/from latitude/longitude are also supported by GCTP.

  1.  Universal Transverse Mercator (UTM)
  2.  State Plane (where the state plane projections are supported for
      either NAD27 or NAD83, but not between NAD27 and NAD83)
  3.  Albers conical equal-area
  4.  Lambert conformal conic
  5.  Mercator
  6.  Polar stereographic
  7.  Polyconic
  8.  Equidistant conic
  9.  Transverse Mercator
  10. Stereographic
  11. Lambert azimuthal equal-area
  12. Azimuthal equidistant
  13. Gnomonic
  14. Orthographic
  15. General vertical near-side perspective
  16. Sinusoidal
  17. Equirectangular
  18. Miller cylindrical
  19. Van der Grinten I
  20. Oblique Mercator (Hotine)

  Note:  Projection parameters are available with the GCTP package for
         the State Plane projections and UTM projections.  For the
         other projections, the user must provide the appropriate
         projection parameters when calling GCTP.

  GCTP is available for a nominal fee ($98.00 US) and can be ordered
  from the following:

          National Geodetic Information Center
          N/CG174, Rockwall Building, Room 24
          National Geodetic Survey, NOAA
          Rockville, Maryland 20852-3019
          Tel:  301/443-8631
          Fax:  301/881-0390

  The GCTP package contains three physical files:  one with the
  VS/FORTRAN source code and two data files containing the State Plane
  Coordinate projection parameters for both NAD27 and NAD83.

  The GCTP documentation (NOAA Technical Report NOS 124 CGS 9) is pro-
  vided along with the package.  This documentation is an essential
  reference for using GCTP.  It includes the encoding information for
  the manner in which concepts such as projection method, zone, and
  measurement unit are provided to GCTP via the main entry point
  GTRNZ0.

  Based on recommendations from the National Geodetic Survey, for any
  transformations which are made involving either state plane coordi-
  nates or the Universal Transverse Mercator (UTM) projection, the
  application should perform the transformation in two steps:

  1.  From the source coordinate system into geographic coordinates
      (latitude/longitude).

  2.  From geographic coordinates (latitude/longitude) into the target
      coordinate system.

  This approach avoids any possible problems which may arise in the
  case where both the "source" and "target" coordinte system use the
  same underlying projection.  For example, some state plane zones use
  Transverse Mercator as their underlying projection.  The Transverse
  Mercator is also the basis for generating UTM coordinates.  The
  internal structure of the GCTP is such that it only allocates
  storage for a single use at a time of a given projection.  There-
  fore, if both the "source" and "target" coordinate systems attempted
  to use, say, the Transverse Mercator projection, the results of the
  GCTP computations will not be valid.  By using geographic coordi-
  nates (latitude/longitude) as intermediate values, the type of
  problem described above is avoided.

-- Scott
--
Scott Kutz                                 internet: sk...@vnet.ibm.com
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