PJ_sconics.c
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#ifndef lint
static const char SCCSID[]="@(#)PJ_sconics.c 4.1 94/05/22 GIE REL";
#endif
#define PROJ_PARMS__ \
double n; \
double rho_c; \
double rho_0; \
double sig; \
double c1, c2; \
int type;
#define PJ_LIB__
#include "projects.h"
#define EULER 0
#define MURD1 1
#define MURD2 2
#define MURD3 3
#define PCONIC 4
#define TISSOT 5
#define VITK1 6
#define EPS10 1.e-10
#define EPS 1e-10
#define LINE2 "\n\tConic, Sph\n\tlat_1= and lat_2="
PROJ_HEAD(tissot, "Tissot")
LINE2;
PROJ_HEAD(murd1, "Murdoch I")
LINE2;
PROJ_HEAD(murd2, "Murdoch II")
LINE2;
PROJ_HEAD(murd3, "Murdoch III")
LINE2;
PROJ_HEAD(euler, "Euler")
LINE2;
PROJ_HEAD(pconic, "Perspective Conic")
LINE2;
PROJ_HEAD(vitk1, "Vitkovsky I")
LINE2;
/* get common factors for simple conics */
static int
phi12(PJ *P, double *del) {
double p1, p2;
int err = 0;
if (!pj_param(P->params, "tlat_1").i ||
!pj_param(P->params, "tlat_2").i) {
err = -41;
} else {
p1 = pj_param(P->params, "rlat_1").f;
p2 = pj_param(P->params, "rlat_2").f;
*del = 0.5 * (p2 - p1);
P->sig = 0.5 * (p2 + p1);
err = (fabs(*del) < EPS || fabs(P->sig) < EPS) ? -42 : 0;
*del = *del;
}
return err;
}
FORWARD(s_forward); /* spheroid */
double rho;
switch (P->type) {
case MURD2:
rho = P->rho_c + tan(P->sig - lp.phi);
break;
case PCONIC:
rho = P->c2 * (P->c1 - tan(lp.phi));
break;
default:
rho = P->rho_c - lp.phi;
break;
}
xy.x = rho * sin( lp.lam *= P->n );
xy.y = P->rho_0 - rho * cos(lp.lam);
return (xy);
}
INVERSE(s_inverse); /* ellipsoid & spheroid */
double rho;
rho = hypot(xy.x, xy.y = P->rho_0 - xy.y);
if (P->n < 0.) {
rho = - rho;
xy.x = - xy.x;
xy.y = - xy.y;
}
lp.lam = atan2(xy.x, xy.y) / P->n;
switch (P->type) {
case PCONIC:
lp.phi = atan(P->c1 - rho / P->c2) + P->sig;
break;
case MURD2:
lp.phi = P->sig - atan(rho - P->rho_c);
break;
default:
lp.phi = P->rho_c - rho;
}
return (lp);
}
FREEUP; if (P) pj_dalloc(P); }
static PJ *
setup(PJ *P) {
double del, cs;
int i;
if( (i = phi12(P, &del)) )
E_ERROR(i);
switch (P->type) {
case TISSOT:
P->n = sin(P->sig);
cs = cos(del);
P->rho_c = P->n / cs + cs / P->n;
P->rho_0 = sqrt((P->rho_c - 2 * sin(P->phi0))/P->n);
break;
case MURD1:
P->rho_c = sin(del)/(del * tan(P->sig)) + P->sig;
P->rho_0 = P->rho_c - P->phi0;
P->n = sin(P->sig);
break;
case MURD2:
P->rho_c = (cs = sqrt(cos(del))) / tan(P->sig);
P->rho_0 = P->rho_c + tan(P->sig - P->phi0);
P->n = sin(P->sig) * cs;
break;
case MURD3:
P->rho_c = del / (tan(P->sig) * tan(del)) + P->sig;
P->rho_0 = P->rho_c - P->phi0;
P->n = sin(P->sig) * sin(del) * tan(del) / (del * del);
break;
case EULER:
P->n = sin(P->sig) * sin(del) / del;
del *= 0.5;
P->rho_c = del / (tan(del) * tan(P->sig)) + P->sig;
P->rho_0 = P->rho_c - P->phi0;
break;
case PCONIC:
P->n = sin(P->sig);
P->c2 = cos(del);
P->c1 = 1./tan(P->sig);
if (fabs(del = P->phi0 - P->sig) - EPS10 >= HALFPI)
E_ERROR(-43);
P->rho_0 = P->c2 * (P->c1 - tan(del));
break;
case VITK1:
P->n = (cs = tan(del)) * sin(P->sig) / del;
P->rho_c = del / (cs * tan(P->sig)) + P->sig;
P->rho_0 = P->rho_c - P->phi0;
break;
}
P->inv = s_inverse;
P->fwd = s_forward;
P->es = 0;
return (P);
}
ENTRY0(euler) P->type = EULER; ENDENTRY(setup(P))
ENTRY0(tissot) P->type = TISSOT; ENDENTRY(setup(P))
ENTRY0(murd1) P->type = MURD1; ENDENTRY(setup(P))
ENTRY0(murd2) P->type = MURD2; ENDENTRY(setup(P))
ENTRY0(murd3) P->type = MURD3; ENDENTRY(setup(P))
ENTRY0(pconic) P->type = PCONIC; ENDENTRY(setup(P))
ENTRY0(vitk1) P->type = VITK1; ENDENTRY(setup(P))