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 (latitude and longitude).  Geographic  coordi-
       nates  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 contain exactly the ones listed below.  To  deter-
       mine  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 directions and relative to Greenwich in
       the  east/west  directions.  The same point will have dif-
       ferent coordinates depending on the spheroid used  as  the
       approximation  of  the shape of the earth.  The geocentric
       coordinates 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 cen-
       ter  of	the  earth, which is why they are called "geocen-
       tric."  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  dis-
       tances 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)
