int gctpc_get_latlon(unsigned char **sec, double **lon, double **lat) {
int gdt;
unsigned char *gds;
double r_maj; /* major axis */
double r_min; /* minor axis */
double lat1; /* first standard parallel */
double lat2; /* second standard parallel */
double c_lon; /* center longitude */
double c_lat; /* center latitude */
double false_east; /* x offset in meters */
double false_north;
double dx, dy;
double x0, y0;
long int (*inv_fn)();
double *llat, *llon, rlon, rlat;
int i, nnx, nny, nres, nscan;
unsigned int nnpnts;
long long_i;
gdt = code_table_3_1(sec);
gds = sec[3];
/* only process certain grids */
if (gdt != 10 && gdt != 20 && gdt != 30 && gdt != 31) return 1;
get_nxny(sec, &nnx, &nny, &nnpnts, &nres, &nscan);
/* potentially staggered */
if (nnx < 1 || nny < 1) return 1;
llat = *lat;
llon = *lon;
if (llat != NULL) {
free(llat);
free(llon);
*lat = *lon = llat = llon = NULL;
}
inv_fn = NULL;
dx = dy = 0.0;
if (gdt == 10) { // mercator
/* get earth axis */
axes_earth(sec, &r_maj, &r_min);
dy = GDS_Mercator_dy(gds);
dx = GDS_Mercator_dx(gds);
/* central point */
c_lon = GDS_Mercator_ori_angle(gds) * (M_PI/180.0);
c_lat = GDS_Mercator_latD(gds) * (M_PI/180.0);
/* find the eastling and northing of of the 1st grid point */
false_east = false_north = 0.0;
long_i = merforint(r_maj,r_min,c_lon,c_lat,false_east,false_north);
rlon = GDS_Mercator_lon1(gds) * (M_PI/180.0);
rlat = GDS_Mercator_lat1(gds) * (M_PI/180.0);
long_i = merfor(rlon, rlat, &x0, &y0);
/* initialize for 1st grid point */
x0 = -x0;
y0 = -y0;
long_i = merinvint(r_maj,r_min,c_lon,c_lat,x0,y0);
inv_fn = &merinv;
}
else if (gdt == 20) { // polar stereographic
/* get earth axis */
axes_earth(sec, &r_maj, &r_min);
dy = GDS_Polar_dy(gds);
dx = GDS_Polar_dx(gds);
/* central point */
c_lon = GDS_Polar_lov(gds) * (M_PI/180.0);
c_lat = GDS_Polar_lad(gds) * (M_PI/180.0);
/* find the eastling and northing of of the 1st grid point */
false_east = false_north = 0.0;
long_i = psforint(r_maj,r_min,c_lon,c_lat,false_east,false_north);
rlon = GDS_Polar_lon1(gds) * (M_PI/180.0);
rlat = GDS_Polar_lat1(gds) * (M_PI/180.0);
long_i = psfor(rlon, rlat, &x0, &y0);
/* initialize for 1st grid point */
x0 = -x0;
y0 = -y0;
long_i = psinvint(r_maj,r_min,c_lon,c_lat,x0,y0);
inv_fn = &psinv;
}
else if (gdt == 30) { // lambert conformal conic
/* get earth axis */
axes_earth(sec, &r_maj, &r_min);
dy = GDS_Lambert_dy(gds);
dx = GDS_Lambert_dx(gds);
//printf(">>> gctpc dx %lf, dy %lf\n", dx, dy);
/* latitudes of tangent/intersection */
lat1 = GDS_Lambert_Latin1(gds) * (M_PI/180.0);
lat2 = GDS_Lambert_Latin2(gds) * (M_PI/180.0);
/* central point */
c_lon = GDS_Lambert_Lov(gds) * (M_PI/180.0);
c_lat = GDS_Lambert_LatD(gds) * (M_PI/180.0);
/* find the eastling and northing of of the 1st grid point */
false_east = false_north = 0.0;
long_i = lamccforint(r_maj,r_min,lat1,lat2,c_lon,c_lat,false_east,false_north);
rlon = GDS_Lambert_Lo1(gds) * (M_PI/180.0);
rlat = GDS_Lambert_La1(gds) * (M_PI/180.0);
long_i = lamccfor(rlon, rlat, &x0, &y0);
/* initialize for 1st grid point */
x0 = -x0;
y0 = -y0;
long_i = lamccinvint(r_maj,r_min,lat1,lat2,c_lon,c_lat,x0,y0);
inv_fn = &lamccinv;
}
else if (gdt == 31) { // albers equal area
/* get earth axis */
axes_earth(sec, &r_maj, &r_min);
dy = GDS_Albers_dy(gds);
dx = GDS_Albers_dx(gds);
/* latitudes of tangent/intersection */
lat1 = GDS_Albers_Latin1(gds) * (M_PI/180.0);
lat2 = GDS_Albers_Latin2(gds) * (M_PI/180.0);
/* central point */
c_lon = GDS_Albers_Lov(gds) * (M_PI/180.0);
c_lat = GDS_Albers_LatD(gds) * (M_PI/180.0);
/* find the eastling and northing of of the 1st grid point */
false_east = false_north = 0.0;
long_i = alberforint(r_maj,r_min,lat1,lat2,c_lon,c_lat,false_east,false_north);
rlon = GDS_Albers_Lo1(gds) * (M_PI/180.0);
rlat = GDS_Albers_La1(gds) * (M_PI/180.0);
long_i = alberfor(rlon, rlat, &x0, &y0);
/* initialize for 1st grid point */
x0 = -x0;
y0 = -y0;
long_i = alberinvint(r_maj,r_min,lat1,lat2,c_lon,c_lat,x0,y0);
inv_fn = &alberinv;
}
if (inv_fn == NULL) return 1;
if ((*lat = llat = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("gctpc_get_latlon memory allocation failed","");
}
if ((*lon = llon = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("gctpc_get_latlon memory allocation failed","");
}
/* put x[] and y[] values in lon and lat */
if (stagger(sec, nnpnts, llon, llat)) fatal_error("gctpc: stagger problem","");
printf(">> stagger gctpc x00 %lf y00 %lf\n",llon[0], llat[0]);
#pragma omp parallel for schedule(static) private(i)
for (i = 0; i < nnpnts; i++) {
inv_fn(llon[i]*dx, llat[i]*dy, llon+i, llat+i);
llat[i] *= (180.0 / M_PI);
llon[i] *= (180.0 / M_PI);
if (llon[i] < 0.0) llon[i] += 360.0;
}
return 0;
}
int proj4_initialize(unsigned char **sec, struct proj4_struct *projection) {
unsigned int gdt;
unsigned char *gds;
int has_np;
double r_maj, r_min, c_lon, c_lat, x_0, y_0, lat1, lon1;
double latsp1, latsp2;
char proj4_def[1000];
gdt = code_table_3_1(sec);
gds = sec[3];
axes_earth(sec, &r_maj, &r_min);
projection->radius_minor = r_min;
projection->radius_minor = r_min;
if (gdt == 0) {
projection->proj_is_nop = 1;
projection->x_0 = projection->y_0 = projection->lat_0 = projection->lon_0 = 0.0;
return 0;
}
projection->proj_is_nop = 0;
sprintf(proj4_def,"+proj=latlong +a=%lf +b=%lf",r_maj, r_min);
if ( (projection->pj_latlon = pj_init_plus(proj4_def)) == NULL)
fatal_error("proj4_initialize: pj_init_plus %s failed", proj4_def);
if (gdt == 10 && (GDS_Mercator_ori_angle(gds) == 0.0) ) { // mercator no rotation
/* central point */
c_lon = 0.0;
c_lat = GDS_Mercator_latD(gds);
sprintf(proj4_def,"+proj=merc +lat_ts=%lf +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +a=%lf +b=%lf",
c_lat, r_maj, r_min);
if ((projection->pj_grid = pj_init_plus(proj4_def)) == NULL) fatal_error("proj4_initialize: pj_init_plus %s failed", proj4_def);
/* longitude, latitude of first grid point */
projection->lat_0 = lat1 = GDS_Mercator_lat1(gds);
projection->lon_0 = lon1 = GDS_Mercator_lon1(gds);
x_0 = lon1 * DEG_TO_RAD;
y_0 = lat1 * DEG_TO_RAD;
if ( pj_transform(projection->pj_latlon, projection->pj_grid, 1, 1, &x_0, &y_0, NULL) != 0 )
fatal_error("proj4_initialize: Proj4 transform to lat-lon","");
projection->x_0 = x_0;
projection->y_0 = y_0;
}
else if (gdt == 20) { // polar stereographic
/* central point */
c_lon = GDS_Polar_lov(gds);
c_lat = GDS_Polar_lad(gds);
/* strange but np/sp flag is used by proj4 but not gctpc */
has_np = ((flag_table_3_5(sec) & 128) == 0);
sprintf(proj4_def,"+proj=stere +lat_ts=%lf +lat_0=%s +lon_0=%lf +k_0=1 +x_0=0 +y_0=0 +a=%lf +b=%lf",
c_lat, has_np ? "90" : "-90", c_lon, r_maj,r_min);
if ((projection->pj_grid = pj_init_plus(proj4_def)) == NULL) fatal_error("Proj4: pj_init_plus %s failed", proj4_def);
/* longitude, latitude of first grid point */
projection->lon_0 = lon1 = GDS_Polar_lon1(gds);
projection->lat_0 = lat1 = GDS_Polar_lat1(gds);
x_0 = lon1 * DEG_TO_RAD;
y_0 = lat1 * DEG_TO_RAD;
if ( pj_transform(projection->pj_latlon, projection->pj_grid, 1, 1, &x_0, &y_0, NULL) != 0 )
fatal_error("proj4_init: Proj4 transform to lat-lon","");
projection->x_0 = x_0;
projection->y_0 = y_0;
}
else if (gdt == 30) { // lambert conformal conic
/* latitudes of tangent/intersection */
latsp1 = GDS_Lambert_Latin1(gds);
latsp2 = GDS_Lambert_Latin2(gds);
/* central point */
c_lon = GDS_Lambert_Lov(gds);
c_lat = GDS_Lambert_LatD(gds);
sprintf(proj4_def,"+proj=lcc +lon_0=%lf +lat_0=%lf +lat_1=%lf +lat_2=%lf +a=%lf +b=%lf",c_lon,
c_lat,latsp1,latsp2,r_maj,r_min);
if ((projection->pj_grid = pj_init_plus(proj4_def)) == NULL) fatal_error("Proj4: pj_init_plus %s failed", proj4_def);
/* longitude, latitude of first grid point */
lon1 = GDS_Lambert_Lo1(gds);
lat1 = GDS_Lambert_La1(gds);
x_0 = lon1 * DEG_TO_RAD;
y_0 = lat1 * DEG_TO_RAD;
/* longitude, latitude of first grid point */
projection->lon_0 = lon1 = GDS_Lambert_Lo1(gds);
projection->lat_0 = lat1 = GDS_Lambert_La1(gds);
x_0 = lon1 * DEG_TO_RAD;
y_0 = lat1 * DEG_TO_RAD;
if ( pj_transform(projection->pj_latlon, projection->pj_grid, 1, 1, &x_0, &y_0, NULL) != 0 )
fatal_error("proj4_init: Proj4 transform to lat-lon","");
projection->x_0 = x_0;
projection->y_0 = y_0;
}
else {
return 1;
}
return 0;
}
int polar2ll(unsigned char **sec, double **llat, double **llon) {
double *lat, *lon;
unsigned char *gds;
double dx, dy, orient, de, de2, dr, tmp, xp, yp, h, lat1, lon1, dr2;
double di, dj, LatD;
int ix, iy;
int nnx, nny, nres, nscan;
unsigned int nnpnts;
get_nxny(sec, &nnx, &nny, &nnpnts, &nres, &nscan);
gds = sec[3];
if (nnx == -1 || nny == -1) {
fprintf(stderr,"Sorry code does not handle variable nx/ny yet\n");
return 0;
}
if ((*llat = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("polar2ll memory allocation failed","");
}
if ((*llon = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("polar2ll memory allocation failed","");
}
lat = *llat;
lon = *llon;
/* based on iplib */
lat1 = GDS_Polar_lat1(gds) * (M_PI/180);
lon1 = GDS_Polar_lon1(gds);
orient = GDS_Polar_lov(gds);
LatD = GDS_Polar_lad(gds);
lon1 *= (M_PI/180.0);
orient *= (M_PI/180.0);
dy = GDS_Polar_dy(gds);
dx = GDS_Polar_dx(gds);
h = 1.0;
if (GDS_Polar_sps(gds)) {
h = -1.0;
/* added 12/19/2008 WNE sps checkout */
orient -= M_PI;
}
// removed 12/11 if (! (GDS_Scan_x(nscan))) dx = -dx;
// removed 12/11 if (! (GDS_Scan_y(nscan))) dy = -dy;
/* 60 probably becomes something else in grib2 */
/* vsm: from comment to grib2 polar template:
"Grid length is in units of 10-3 m at the latitude specified by LaD"
do use GDS_Polar_lad(gds) instead of 60?
Do use fabs for southern hemisphere?
*/
de = (1.0 + sin(fabs(LatD)*(M_PI/180.0))) * radius_earth(sec);
dr = de * cos(lat1) / (1 + h*sin(lat1));
xp=-h*sin(lon1-orient)*dr/dx;
yp= cos(lon1-orient)*dr/dy;
// added 12/11
if (! (GDS_Scan_y(nscan))) {
yp = yp - nny + 1;
}
if (! (GDS_Scan_x(nscan))) {
xp = xp - nnx + 1;
}
de2 = de*de;
#pragma omp parallel for private(iy,ix,di,dj,dr2,tmp)
for (iy = 0; iy < nny; iy++) {
for (ix = 0; ix < nnx; ix++) {
di = (ix - xp) * dx;
dj = (iy - yp) * dy;
dr2 = di*di + dj*dj;
if (dr2 < de2*1e-6) {
lon[ix+iy*nx] = 0.0;
lat[ix+iy*nx] = h*90.0;
} else {
tmp = (orient+h*atan2(di,-dj))*(180.0/M_PI);
if (tmp < 0.0) tmp += 360.0;
if (tmp > 360.0) tmp -= 360.0;
lon[ix+iy*nx] = tmp;
lat[ix+iy*nx] = h*asin((de2-dr2)/(de2+dr2))*(180.0/M_PI);
}
}
}
return 0;
}
