WORLD 1L "4 September 1986"

Table of contents


NAME

world - world map generation program from <PLOT79> package

SYNOPSIS

world[1,4,b,r,s,v,z]
where the final character indicates the desired output device
(4 for the Tektronix 4014 in the default Sun installation)
(see plot79 manual page for complete list)

DESCRIPTION

World draws maps of the world, using a variety of coordinate systems. It sends prompts to the standard output requesting information to define the style of map. The map coordinates must appear in file mapfile. A message is sent to standard output, a run-time listing is sent to listfile, and an optional sitefile may specify points on the map which are to be marked (it contains a list of [longitude,latitude,name] triples in format [2f9.3,1x,a]). The plottable output is sent to a file named by the CRT environment variable, or to CRT.num if CRT is undefined (num is a number which begins at 1 and is incremented appropriately to prevent files being overwritten).

The program may be employed for any spherical system. Longitude and latitude values are measured in floating-point degrees. The arguments requested by the program are:

BLON
Beginning longitude for projection.
ELON
Ending longitude for projection. This may be smaller than BLON, in which case the projection is assumed to cross the 180-degree meridian, and the internval value of ELON will automatically be increased by 360 degrees.
BLAT
Beginning latitude for projection. For polar projections, only the sign is relevant; a negative value selects a south polar view, and a zero or positive value a north polar view.
ELAT
Ending latitude for projection.
CLON
Longitude of center of projection.
CLAT
Latitude of center of projection.
ELEV
Relative elevation of viewer above the Earth's surface, expressed as a fraction of the planetary radius. Earth has a mean radius of 6378.0 km, so that a viewer elevation of 250 km would be expressed as ELEV = 250.0/6378.0 = 0.039197.

Not all of these parameters are required by each projection. Here is a list of those actually used:


Proj.	Description	Parameters Required
1	Rectangular	BLAT, BLON, ELAT, ELON
2	Mercator	BLAT, BLON, ELAT, ELON
3	Polar Equidistant	BLAT
4	Orthographic Equatorial	CLAT, CLON
5	Orthographic Polar	BLAT
6	Azimuthal Equidistant	CLAT, CLON
7	Perspective	BLAT, BLON, ELEV, ELAT, ELON
8	Cylindrical Equal Area	BLAT, BLON, ELAT, ELON

The usual cartographic convention is adopted that latitude runs from -90 degrees at the South Pole through 0 at the Equator to +90 degrees at the North Pole, and that longitude runs from 0 degrees through Greenwich, England, eastward to 180 degrees in the Pacific Ocean and back to Greenwich at 360 degrees. Longitude is thus synonomous with East Longitude; West Longitude can be considered a negative value which when incremented by 360 degrees becomes East Longitude.

The map projection routines will internally automatically adjust longitudes in the interval [-360 to 720] to the interval [0 to 360]; latitude values are assumed to be confined to the interval [-90 to +90]. Unpredicatable results may occur if this convention is not adhered to.


FILES

/usr/local/plot79/map/world.map
Hershey World Data Bank I world outline map
/usr/local/plot79/map/usa.map
Hershey World Data Bank I USA outline map
usr/local/plot79/map/*.sf3
source files for world*
/usr/local/plot79/world*
executable file (world4 on the default Sun installation)
/usr/local/plot79/define
various environment definitions, an appropriate subset of which should be placed in the user's .cshrc or .profile file

SEE ALSO

document (1L), drawit(1L), grapht(1L), graph3t(1L), lptops(1L), pfort(1L), piechtt(1L), plot79-intro(1L), plot79(1L), pluto(1L), pretty(1L), rdinfo(1L), sf3(1L), slides(1L), tekalw(1L), tkvecs(1L), tmacro(1L)

A. V. Hershey, "Terrestrial and Celestial Cartography", Report NSWC/DL TR-3789, May 1979, Naval Surface Weapons Center, Dahlgren, VA 22448.

William D. Johnson, "Computer Generated Maps. Part I", pp. 10-12, 76-101, Byte Magazine, Vol. 4, No. 5 (May 1979), and "Computer Generated Maps. Part II", pp. 100-123, ibid, No. 6 (June 1979).

J. E. Jackson, "Sphere, Spheroid and Projections for Surveyors", Granada Publishing Ltd. (1980).


AUTHOR

Nelson H. F. Beebe, Ph.D.
Center for Scientific Computing
South Physics Building
University of Utah
Salt Lake City, UT 84112
Tel: (801) 581-5254
(Manual page by R. P. C. Rodgers, Computer Applications in Laboratory Medicine Project, UCSF, San Francisco, CA 94143).