/***************************************************************************/
/* */
/* geodtm */
/* */
/* Routine to convert from latitude and longitude to Transverse Mercator.*/
/* Method based on Redfearn's formulation as expressed in GDA technical */
/* manual at http://www.anzlic.org.au/icsm/gdatm/index.html */
/* Loosely based on FORTRAN source code by J.Hannah and A.Broadhurst. */
/* */
/* Takes parameters */
/* input latitude (radians) */
/* input longitude (radians) */
/* output easting (metres) */
/* output northing (metres) */
/* */
/***************************************************************************/
private static void geod_tm(tmprojection *tm,
double ln, double lt, double *ce, double *cn)
{
double fn = tm->falsen;
double fe = tm->falsee;
double sf = tm->scalef;
double e2 = tm->e2;
double a = tm->a;
double cm = tm->meridian;
double om = tm->om;
double utom = tm->utom;
double dlon;
double m;
double slt;
double eslt;
double eta;
double rho;
double psi;
double clt;
double w;
double wc;
double wc2;
double t;
double t2;
double t4;
double t6;
double trm1;
double trm2;
double trm3;
double gce;
double trm4;
double gcn;
dlon = ln - cm;
while (dlon > PI)
{
dlon -= TWOPI;
}
while (dlon < -PI)
{
dlon += TWOPI;
}
m = meridian_arc(tm, lt);
slt = Math.Sin(lt);
eslt = (1.0 - e2 * slt * slt);
eta = a / Math.Sqrt(eslt);
rho = eta * (1.0 - e2) / eslt;
psi = eta / rho;
clt = Math.Cos(lt);
w = dlon;
wc = clt * w;
wc2 = wc * wc;
t = slt / clt;
t2 = t * t;
t4 = t2 * t2;
t6 = t2 * t4;
trm1 = (psi - t2) / 6.0;
trm2 = (((4.0 * (1.0 - 6.0 * t2) * psi
+ (1.0 + 8.0 * t2)) * psi
- 2.0 * t2) * psi + t4) / 120.0;
trm3 = (61 - 479.0 * t2 + 179.0 * t4 - t6) / 5040.0;
gce = (sf * eta * dlon * clt) * (((trm3 * wc2 + trm2) * wc2 + trm1) * wc2 + 1.0);
*ce = gce / utom + fe;
trm1 = 1.0 / 2.0;
trm2 = ((4.0 * psi + 1) * psi - t2) / 24.0;
trm3 = ((((8.0 * (11.0 - 24.0 * t2) * psi
- 28.0 * (1.0 - 6.0 * t2)) * psi
+ (1.0 - 32.0 * t2)) * psi
- 2.0 * t2) * psi
+ t4) / 720.0;
trm4 = (1385.0 - 3111.0 * t2 + 543.0 * t4 - t6) / 40320.0;
gcn = (eta * t) * ((((trm4 * wc2 + trm3) * wc2 + trm2) * wc2 + trm1) * wc2);
*cn = (gcn + m - om) * sf / utom + fn;
return;
}
/* Functions implementation the TM projection specifically for the
* NZTM coordinate system
*/
public static void nztm_geod(double n, double e, double *lt, double *ln)
{
tmprojection *nztm = get_nztm_projection();
tm_geod(nztm, e, n, ln, lt);
}
/***************************************************************************/
/* */
/* tmgeod */
/* */
/* Routine to convert from Tranverse Mercator to latitude and longitude. */
/* Method based on Redfearn's formulation as expressed in GDA technical */
/* manual at http://www.anzlic.org.au/icsm/gdatm/index.html */
/* */
/* Takes parameters */
/* input easting (metres) */
/* input northing (metres) */
/* output latitude (radians) */
/* output longitude (radians) */
/* */
/***************************************************************************/
private static void tm_geod(tmprojection *tm,
double ce, double cn, double *ln, double *lt)
{
double fn = tm->falsen;
double fe = tm->falsee;
double sf = tm->scalef;
double e2 = tm->e2;
double a = tm->a;
double cm = tm->meridian;
double om = tm->om;
double utom = tm->utom;
double cn1;
double fphi;
double slt;
double clt;
double eslt;
double eta;
double rho;
double psi;
double E;
double x;
double x2;
double t;
double t2;
double t4;
double trm1;
double trm2;
double trm3;
double trm4;
cn1 = (cn - fn) * utom / sf + om;
fphi = foot_point_lat(tm, cn1);
slt = Math.Sin(fphi);
clt = Math.Cos(fphi);
eslt = (1.0 - e2 * slt * slt);
eta = a / Math.Sqrt(eslt);
rho = eta * (1.0 - e2) / eslt;
psi = eta / rho;
E = (ce - fe) * utom;
x = E / (eta * sf);
x2 = x * x;
t = slt / clt;
t2 = t * t;
t4 = t2 * t2;
trm1 = 1.0 / 2.0;
trm2 = ((-4.0 * psi
+ 9.0 * (1 - t2)) * psi
+ 12.0 * t2) / 24.0;
trm3 = ((((8.0 * (11.0 - 24.0 * t2) * psi
- 12.0 * (21.0 - 71.0 * t2)) * psi
+ 15.0 * ((15.0 * t2 - 98.0) * t2 + 15)) * psi
+ 180.0 * ((-3.0 * t2 + 5.0) * t2)) * psi + 360.0 * t4) / 720.0;
trm4 = (((1575.0 * t2 + 4095.0) * t2 + 3633.0) * t2 + 1385.0) / 40320.0;
*lt = fphi + (t * x * E / (sf * rho)) * (((trm4 * x2 - trm3) * x2 + trm2) * x2 - trm1);
trm1 = 1.0;
trm2 = (psi + 2.0 * t2) / 6.0;
trm3 = (((-4.0 * (1.0 - 6.0 * t2) * psi
+ (9.0 - 68.0 * t2)) * psi
+ 72.0 * t2) * psi
+ 24.0 * t4) / 120.0;
trm4 = (((720.0 * t2 + 1320.0) * t2 + 662.0) * t2 + 61.0) / 5040.0;
*ln = cm - (x / clt) * (((trm4 * x2 - trm3) * x2 + trm2) * x2 - trm1);
}
