[Proj] pms finally comes to project projection library

Gerald I. Evenden geraldi.evenden at gmail.com
Fri May 15 13:53:46 EST 2009

The prime meridian system offset option has finally been added to the 
projection library.  There are two ways to use it:

1. use the list of "standard" prime meridians from the list below:

sproj -l pms
      Athens : 23d42'58.815"E
        Bern : 7d26'22.5"E
      Bogota : 74d04'51.3"W
    Brussels : 4d22'4.71"E
       Ferro : 17d40'W
   Greenwich : 0dE
     Jakarta : 106d48'27.79"E
      Lisbon : 9d07'54.862"W
      Madrid : 3d41'16.58"W
        Oslo : 10d43'22.5"E
       Paris : 2d20'14.025"E
        Rome : 12d27'8.4"
   Stockholm : 18d3'29.8"E

and using as

sproj proj=poly ellps=wgs84 pms=ferro

List spiked from Warmerdams proj-4.6.1 and unverified.

2, or by specifying your own value such as:

sproj proj=poly ellps=wgs84 pms=2d30.7W

The pms offset only applies to only correcting the data to the Greenwich 
meridian and any longitude values related to projection definition are in the 
coordinate system of the original system.  This is demonstrated below:

sproj proj=tmerc ellps=wgs84 lon_0=5 pms=7d33\'14 -I <<EOF
0 0
12d33'14.000"E  0d00'00.000"N

Using the projection inverse shows shows more readily where the CM ends up.

sproj is a basic, no frills projection rooutine:

sproj -h
Short Cartographic Projection Computer v. 1.0

Compute forward or inverse cartographic projections

Usage: sproj [OPTIONS] [projection options]

A program to compute forward or inverse cartographic projection.
  -h, --help                 Print help and exit
      --detailed-help        Print help, including all details and hidden
                               options, and exit
  -V, --version              Print version and exit
  -I, --inverse              Inverse projection  (default=off)
  -r, --revin                reverse order of input to phi-lam or y-x
  -R, --revout               reverse order of output to y-x or phi-lam
  -f, --format=C_format_str  output format
  -l, --list=ENUM            list options  (possible values="proj",
                               "ellps", "pms", "units" default=`proj')
  -P, --longproj[=proj_id]   detail projection list

Data I/O is through stdin/out and geographic data may be in either DMS or 
colon format.  User can format colon for output.  I will probably flesh sproj 
out more in the future.

I should be able to get this whole ball of wax on my web site by Sunday, 17 
May, barring any more autoconf, el al disasters. :-(

The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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