m.ll2gc(1)		      Grass User's Manual		    m.ll2gc(1)



NNAAMMEE
       mm..llll22ggcc	- Converts geographic coordinates to geocentric coordinates.
       (GRASS Data Import/Processing Program)

SSYYNNOOPPSSIISS
       mm..llll22ggcc llaatt==_d_d_._m_m_._s_s{_n|_s} lloonn==_d_d_._m_m_._s_s{_e|_w} [hh==_h_e_i_g_h_t] ss==_s_p_h_e_r_o_i_d

DDEESSCCRRIIPPTTIIOONN
       _m_._l_l_2_g_c returns geocentric coordinates for geographic coordinates (lat-
       itude and longitude).  Geographic coordinates are in degrees,  minutes,
       and  seconds  and  must include designation of north or south {_n|_s} and
       east or west {_e|_w}.  The spheroid on which they are based must also  be
       entered.  The height (in meters) above the spheroid is optional.


       The  list  of spheroids available is somewhat dynamic.  It may not con-
       tain exactly the ones listed below.  To determine the current  list  of
       possible spheroids, type in: mm..llll22ggcc llaatt==_0_n lloonn==_0_w ss==_h_e_l_p

       A  list	of  available spheroids will be printed on the screen.	If the
       spheroid desired is not on the list, the values for the semi-major axis
       and  the  eccentricity squared for the spheroid may be entered in place
       of   a	spheroid   name   in   the   following	  format:    ss==aa==_s_e_m_i_-
       _m_a_j_o_r___a_x_i_s,ee==_e_c_c_e_n_t_r_i_c_i_t_y___s_q_u_a_r_e_d


   SSOOMMEE PPOOSSSSIIBBLLEE SSPPHHEERROOIIDDSS
       (_T_h_e _o_n_-_l_i_n_e _l_i_s_t_i_n_g _i_n_c_l_u_d_e_s _o_n_l_y _t_h_e _s_p_h_e_r_o_i_d _n_a_m_e_s)
       Spheroid      |	 Commonly  used  for:|	Semi-major axis|  Eccentricity
       sqrd
       _____________|____________________|_________________|___________________
       australian   |  Australia	 |  6378160.0	   |  0.0066945419
       bessel	    |  Japan		 |  6377739.155    |  0.0066743722
       clark66	    |  N. America	 |  6378206.4	   |  0.006768658
       clark80	    |  France, Africa	 |  6378249.145    |  0.0068035113
       everest	    |  India, Burma	 |  6377276.345    |  0.0066378466
       international|  Europe		 |  6378388.0	   |  0.00672267
       wgs72	    |  worldwide coverage|  6378135.0	   |  0.006694317778


EEXXAAMMPPLLEE
       mm..llll22ggcc llaatt==_0_n lloonn==_9_0_w ss==_w_g_s_7_2

       Results: 4
	      x=0.0

	      y=6378135.0

	      z=0.0

       The  distances  designated  by  "x," "y" and "z" are in meters from the
       center of the earth. Because the sample point is on the equator and  is
       at  90  degrees	west, two of the three parameters have a value of zero
       (i.e., the point is at the origin of those two dimensions).

NNOOTTEESS
       For a brief discussion of spheroids see _m_._l_l_2_u.


       Geographic coordinates (latitude/longitude) describe the location of  a
       point  on  the  earth relative to the equator in the north/south direc-
       tions and relative to Greenwich in the east/west directions.  The  same
       point will have different coordinates depending on the spheroid used as
       the approximation of the shape of the earth.   The  geocentric  coordi-
       nates  given here describe the point on the basis of the same spheroid,
       but they use the center of the spheroid as their origin.  This  can  be
       thought	of  as	being  the  center of the earth, which is why they are
       called "geocentric."  Describing the location of a point in a  spheroid
       requires  three	points:  x, y, and z;  these are measured out from the
       center along three different axes.  The distances given are in  meters.


       This  is  an  experimental  program.   It is part of initial efforts to
       incorporate geographic coordinates into GRASS.

SSEEEE AALLSSOO
       _m_._d_a_t_u_m_._s_h_i_f_t

       _m_._g_c_2_l_l

       _m_._l_l_2_u

       _m_._u_2_l_l

AAUUTTHHOORR
       Michael Shapiro, U.S.Army Construction Engineering Research Laboratory

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_3 _$



GRASS 5.0							    m.ll2gc(1)
