diff options
Diffstat (limited to 'src/projections/tmerc.cpp')
| -rw-r--r-- | src/projections/tmerc.cpp | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/src/projections/tmerc.cpp b/src/projections/tmerc.cpp new file mode 100644 index 00000000..5a2dacbd --- /dev/null +++ b/src/projections/tmerc.cpp @@ -0,0 +1,210 @@ +#define PJ_LIB__ + +#include <errno.h> +#include <math.h> + +#include "proj.h" +#include "projects.h" + +PROJ_HEAD(tmerc, "Transverse Mercator") "\n\tCyl, Sph&Ell"; + + +namespace { // anonymous namespace +struct pj_opaque { + double esp; + double ml0; + double *en; +}; +} // anonymous namespace + +#define EPS10 1.e-10 +#define FC1 1. +#define FC2 .5 +#define FC3 .16666666666666666666 +#define FC4 .08333333333333333333 +#define FC5 .05 +#define FC6 .03333333333333333333 +#define FC7 .02380952380952380952 +#define FC8 .01785714285714285714 + + +static XY e_forward (LP lp, PJ *P) { /* Ellipsoidal, forward */ + XY xy = {0.0, 0.0}; + struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque); + double al, als, n, cosphi, sinphi, t; + + /* + * Fail if our longitude is more than 90 degrees from the + * central meridian since the results are essentially garbage. + * Is error -20 really an appropriate return value? + * + * http://trac.osgeo.org/proj/ticket/5 + */ + if( lp.lam < -M_HALFPI || lp.lam > M_HALFPI ) { + xy.x = HUGE_VAL; + xy.y = HUGE_VAL; + pj_ctx_set_errno( P->ctx, PJD_ERR_LAT_OR_LON_EXCEED_LIMIT ); + return xy; + } + + sinphi = sin (lp.phi); + cosphi = cos (lp.phi); + t = fabs (cosphi) > 1e-10 ? sinphi/cosphi : 0.; + t *= t; + al = cosphi * lp.lam; + als = al * al; + al /= sqrt (1. - P->es * sinphi * sinphi); + n = Q->esp * cosphi * cosphi; + xy.x = P->k0 * al * (FC1 + + FC3 * als * (1. - t + n + + FC5 * als * (5. + t * (t - 18.) + n * (14. - 58. * t) + + FC7 * als * (61. + t * ( t * (179. - t) - 479. ) ) + ))); + xy.y = P->k0 * (pj_mlfn(lp.phi, sinphi, cosphi, Q->en) - Q->ml0 + + sinphi * al * lp.lam * FC2 * ( 1. + + FC4 * als * (5. - t + n * (9. + 4. * n) + + FC6 * als * (61. + t * (t - 58.) + n * (270. - 330 * t) + + FC8 * als * (1385. + t * ( t * (543. - t) - 3111.) ) + )))); + return (xy); +} + + +static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */ + XY xy = {0.0,0.0}; + double b, cosphi; + + /* + * Fail if our longitude is more than 90 degrees from the + * central meridian since the results are essentially garbage. + * Is error -20 really an appropriate return value? + * + * http://trac.osgeo.org/proj/ticket/5 + */ + if( lp.lam < -M_HALFPI || lp.lam > M_HALFPI ) { + xy.x = HUGE_VAL; + xy.y = HUGE_VAL; + pj_ctx_set_errno( P->ctx, PJD_ERR_LAT_OR_LON_EXCEED_LIMIT ); + return xy; + } + + cosphi = cos(lp.phi); + b = cosphi * sin (lp.lam); + if (fabs (fabs (b) - 1.) <= EPS10) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return xy; + } + + xy.x = static_cast<struct pj_opaque*>(P->opaque)->ml0 * log ((1. + b) / (1. - b)); + xy.y = cosphi * cos (lp.lam) / sqrt (1. - b * b); + + b = fabs ( xy.y ); + if (b >= 1.) { + if ((b - 1.) > EPS10) { + proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION); + return xy; + } + else xy.y = 0.; + } else + xy.y = acos (xy.y); + + if (lp.phi < 0.) + xy.y = -xy.y; + xy.y = static_cast<struct pj_opaque*>(P->opaque)->esp * (xy.y - P->phi0); + return xy; +} + + +static LP e_inverse (XY xy, PJ *P) { /* Ellipsoidal, inverse */ + LP lp = {0.0,0.0}; + struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque); + double n, con, cosphi, d, ds, sinphi, t; + + lp.phi = pj_inv_mlfn(P->ctx, Q->ml0 + xy.y / P->k0, P->es, Q->en); + if (fabs(lp.phi) >= M_HALFPI) { + lp.phi = xy.y < 0. ? -M_HALFPI : M_HALFPI; + lp.lam = 0.; + } else { + sinphi = sin(lp.phi); + cosphi = cos(lp.phi); + t = fabs (cosphi) > 1e-10 ? sinphi/cosphi : 0.; + n = Q->esp * cosphi * cosphi; + d = xy.x * sqrt (con = 1. - P->es * sinphi * sinphi) / P->k0; + con *= t; + t *= t; + ds = d * d; + lp.phi -= (con * ds / (1.-P->es)) * FC2 * (1. - + ds * FC4 * (5. + t * (3. - 9. * n) + n * (1. - 4 * n) - + ds * FC6 * (61. + t * (90. - 252. * n + + 45. * t) + 46. * n + - ds * FC8 * (1385. + t * (3633. + t * (4095. + 1575. * t)) ) + ))); + lp.lam = d*(FC1 - + ds*FC3*( 1. + 2.*t + n - + ds*FC5*(5. + t*(28. + 24.*t + 8.*n) + 6.*n + - ds * FC7 * (61. + t * (662. + t * (1320. + 720. * t)) ) + ))) / cosphi; + } + return lp; +} + + +static LP s_inverse (XY xy, PJ *P) { /* Spheroidal, inverse */ + LP lp = {0.0, 0.0}; + double h, g; + + h = exp(xy.x / static_cast<struct pj_opaque*>(P->opaque)->esp); + g = .5 * (h - 1. / h); + h = cos (P->phi0 + xy.y / static_cast<struct pj_opaque*>(P->opaque)->esp); + lp.phi = asin(sqrt((1. - h * h) / (1. + g * g))); + + /* Make sure that phi is on the correct hemisphere when false northing is used */ + if (xy.y < 0. && -lp.phi+P->phi0 < 0.0) lp.phi = -lp.phi; + + lp.lam = (g != 0.0 || h != 0.0) ? atan2 (g, h) : 0.; + return lp; +} + + +static PJ *destructor(PJ *P, int errlev) { /* Destructor */ + if (nullptr==P) + return nullptr; + + if (nullptr==P->opaque) + return pj_default_destructor(P, errlev); + + pj_dealloc (static_cast<struct pj_opaque*>(P->opaque)->en); + return pj_default_destructor(P, errlev); +} + + +static PJ *setup(PJ *P) { /* general initialization */ + struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque); + if (P->es != 0.0) { + if (!(Q->en = pj_enfn(P->es))) + return pj_default_destructor(P, ENOMEM); + + Q->ml0 = pj_mlfn(P->phi0, sin(P->phi0), cos(P->phi0), Q->en); + Q->esp = P->es / (1. - P->es); + P->inv = e_inverse; + P->fwd = e_forward; + } else { + Q->esp = P->k0; + Q->ml0 = .5 * Q->esp; + P->inv = s_inverse; + P->fwd = s_forward; + } + return P; +} + + +PJ *PROJECTION(tmerc) { + struct pj_opaque *Q = static_cast<struct pj_opaque*>(pj_calloc (1, sizeof (struct pj_opaque))); + if (nullptr==Q) + return pj_default_destructor (P, ENOMEM); + + P->opaque = Q; + P->destructor = destructor; + + return setup(P); +} |