ncl_maproj man page

MAPROJ — Sets the map projection to be used.



C-Binding Synopsis

#include <ncarg/ncargC.h>

void c_maproj (char *jprj, float plat, float plon,
float rota)



(an input expression, of type CHARACTER) defines the desired projection type. All the possible values are two characters in length; these are the possibilities:

The conic projection:

'LC' -
Lambert conformal conic with two standard parallels.

The azimuthal projections:

'ST' -
'OR' -
Orthographic. The EZMAP parameter 'SA' will be zeroed. See the note below.
'LE' -
Lambert equal area.
'GN' -
'AE' -
Azimuthal equidistant.
'SV' -
Satellite-view. If the EZMAP parameter 'SA' is less than or equal to 1., it will be reset to 6.631 (the value for a satellite in a geosynchronous orbit). See the note below.

The cylindrical projections:

'CE' -
Cylindrical equidistant.
'ME' -
'MO' -

Note: The orthographic and satellite-view projections have the same internal identifier. The EZMAP parameter 'SA' determines which will be used. If a call to MAPROJ selecting one or the other is followed by a call to MAPSTR resetting 'SA', it may have the effect of causing the other to be used.


(input expressions, of type REAL) are angular quantities, in degrees. How they are used depends on the value of JPRJ, as follows:

If JPRJ is not equal to 'LC': PLAT and PLON define the latitude and longitude of the pole of the projection, the point on the globe which is to project to the origin of the u/v plane. PLAT must be between -90. and +90., inclusive, positive in the northern hemisphere, negative in the southern. PLON must be between -180. and +180., inclusive, positive to the east, and negative to the west, of Greenwich. ROTA is the angle between the v axis and north at the origin. It is taken to be positive if the angular movement from north to the v axis is counter-clockwise, negative otherwise. If the origin is at the north pole, "north" is considered to be in the direction of PLON+180. If the origin is at the south pole, "north" is considered to be in the direction of PLON. For the cylindrical projections, the axis of the projection is parallel to the v axis.
If JPRJ is equal to 'LC': PLON defines the central meridian of the projection, and PLAT and ROTA define the two standard parallels. If PLAT and ROTA are equal, a simpler conic projection, with one standard parallel, is used.

C-Binding Description

The C-binding argument descriptions are the same as the FORTRAN argument descriptions.


This routine allows you to set the current values of the EZMAP parameters 'PR', 'PT', 'PN', and 'RO'. For a complete list of parameters available in this utility, see the ezmap_params man page.


Use the ncargex command to see the following relevant examples: ccpcica, ccpmap, ccpmovi, ccppole, ccpvp, colcon, cezmap1, cezmap2, cezmap3, cmpclr, cmpdd, cmpdrw, cmpel, cmpfil, cmpgrd, cmpgrp, cmpita, cmpitm, cmplab, cmplbl, cmplot, cmpmsk, cmpou, cmpsat, cmptit, cmptra, cmpusr, cpex01, cpex03, cpex08, cpex09, mpex01, mpex02, mpex04, mpex05, mpex06, mpex07, mpex09, mpex10, eezmpa, epltch, tezmap, tezmpa, fcover, ffex00, ffex02, ffex03, ffex05, fgkgtx, fngngdts, fpchiqu.


To use MAPROJ or c_maproj, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.


See the ezmap man page for a description of all EZMAP error messages and/or informational messages.

See Also

Online: ezmap, ezmap_params, mapaci, mapbla, mapblm, mapdrw, mapeod, mapfst, mapgci, mapgrd, mapgrm, mapgtc, mapgti, mapgtl, mapgtr, mapint, mapiq, mapiqa, mapiqd, mapiqm, mapit, mapita, mapitd, mapitm, maplbl, maplmb, maplot, mappos, maprs, maprst, mapsav, mapset, mapstc, mapsti, mapstl, mapstr, maptra, maptri, maptrn, mapusr, mapvec, mpchln, mpfnme, mpgetc, mpgeti, mpgetl, mpgetr, mpglty, mpiaty, mpifnb, mpilnb, mpiola, mpiosa, mpipai, mpipan, mpipar, mpisci, mplnam, mplndm, mplndr, mplnri, mpname, mprset, mpsetc, mpseti, mpsetl, mpsetr, supmap, supcon, ncarg_cbind

Hardcopy: NCAR Graphics Contouring and Mapping Tutorial