int regular2ll(unsigned char **sec, double **lat, double **lon) {
int basic_ang, sub_ang;
double units, dlat, dlon, lat1, lat2, lon1, lon2;
double e, w, n, s, dx, dy;
int i, j;
double *llat, *llon;
unsigned char *gds;
int nnx, nny, nres, nscan;
unsigned int nnpnts;
get_nxny(sec, &nnx, &nny, &nnpnts, &nres, &nscan);
gds = sec[3];
if (nny == -1) {
fprintf(stderr,"Sorry code does not handle variable ny yet\n");
return 0;
}
if ((*lat = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("regular2ll memory allocation failed","");
}
if ((*lon = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("regular2ll memory allocation failed","");
}
/* now figure out the grid coordinates mucho silly grib specification */
basic_ang = GDS_LatLon_basic_ang(gds);
sub_ang = GDS_LatLon_sub_ang(gds);
if (basic_ang != 0) {
units = (double) basic_ang / (double) sub_ang;
}
else {
units = 0.000001;
}
dlat = GDS_LatLon_dlat(gds) * units;
dlon = GDS_LatLon_dlon(gds) * units;
lat1 = GDS_LatLon_lat1(gds) * units;
lat2 = GDS_LatLon_lat2(gds) * units;
lon1 = GDS_LatLon_lon1(gds) * units;
lon2 = GDS_LatLon_lon2(gds) * units;
if (lon1 < 0.0 || lon2 < 0.0) fatal_error("BAD grid definition lon < zero","");
if (lon1 > 360.0 || lon2 > 360.0) fatal_error("BAD grid definition lon >= 360","");
if (lat1 < -90.0 || lat2 < -90.0 || lat1 > 90.0 || lat2 > 90.0) fatal_error("BAD grid definition lat","");
/* find S latitude and dy */
if (GDS_Scan_y(nscan)) {
s = lat1;
n = lat2;
}
else {
s = lat2;
n = lat1;
}
if (s > n) fatal_error("lat-lon grid: lat1 and lat2 inconsistent with scan order","");
if (nny != 1) {
dy = (n - s) / (nny - 1);
if (nres & 16) { /* lat increment is valid */
if (fabs(dy - dlat) > 0.001) fatal_error("lat-lon grid: dlat is inconsistent","");
}
}
else {
dy = 0.0;
}
// fprintf(stderr,">>> geo: dy %lf dlat %lf nres %d has dy %d has dx %d\n", dy, dlat, nres, nres & 16, nres & 32);
/* find W latitude and dx */
if ( GDS_Scan_row_rev(nscan) && (nny % 2 == 0) && ((nres & 32) == 0) ) {
fatal_error("grib GDS ambiguity","");
}
if (GDS_Scan_x(nscan)) {
w = lon1;
e = lon2;
if (GDS_Scan_row_rev(nscan) && ((nres & 32) == 0)) {
e = lon1 + (nnx-1) * dlon;
}
} else {
w = lon2;
e = lon1;
if (GDS_Scan_row_rev(nscan) && ((nres & 32) == 0)) {
w = lon1 - (nnx-1) * dlon;
}
}
if (e <= w) e += 360.0;
if (e-w > 360.0) e -= 360.0;
if (w < 0) {
w += 360.0;
e += 360.0;
}
/* lat-lon should be in a WE:SN order */
if (nnx > 0 && nny > 0) { /* non-thinned, potentially staggered grid */
/* put x[] and y[] values in lon[] and lat[] */
llat = *lat;
llon = *lon;
if (stagger(sec, nnpnts,llon,llat)) fatal_error("geo: stagger problem","");
if (nnx != 1) {
dx = (e-w) / (nnx - 1);
dx = fabs(dx);
if (nres & 32) { /* lon increment is valid */
if (fabs(dx - fabs(dlon)) > 0.001) fatal_error("lat-lon grid: dlon is inconsistent","");
}
}
else {
dx = 0.0;
}
dy = fabs(dy);
#pragma omp parallel for private(j)
for (j = 0; j < nnpnts; j++) {
llon[j] = lon1 + llon[j]*dx;
llon[j] = llon[j] >= 360.0 ? llon[j] - 360.0 : llon[j];
llon[j] = llon[j] < 0.0 ? llon[j] + 360.0 : llon[j];
llat[j] = lat1 + llat[j]*dy;
}
return 0;
}
/* must be thinned grid */
llat = *lat;
/* quasi-regular grid */
for (j = 0; j < nny; j++) {
for (i = 0; i < variable_dim[j]; i++) {
*llat++ = s + j*dy;
}
}
llon = *lon;
/* quasi-regular grid */
for (j = 0; j < nny; j++) {
dx = (e-w) / (variable_dim[j]-1);
for (i = 0; i < variable_dim[j]; i++) {
*llon++ = w + i*dx >= 360.0 ? w + i*dx - 360.0: w + i*dx;
}
}
return 0;
} /* end regular2ll() */
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 lambert2ll(unsigned char **sec, double **llat, double **llon) {
double n;
double *lat, *lon;
double dx, dy, lat1r, lon1r, lon2d, lon2r, latin1r, latin2r;
double lond, latd, d_lon;
double f, rho, rhoref, theta, startx, starty;
int j, nnx, nny, nres, nscan;
double x, y, tmp;
unsigned char *gds;
double latDr;
double earth_radius;
unsigned int nnpnts;
get_nxny(sec, &nnx, &nny, &nnpnts, &nres, &nscan);
if (nnx <= 0 || nny <= 0) {
fprintf(stderr,"Sorry code does not handle variable nx/ny yet\n");
return 0;
}
earth_radius = radius_earth(sec);
gds = sec[3];
dy = GDS_Lambert_dy(gds);
dx = GDS_Lambert_dx(gds);
lat1r = GDS_Lambert_La1(gds) * (M_PI / 180.0);
lon1r = GDS_Lambert_Lo1(gds) * (M_PI / 180.0);
lon2d = GDS_Lambert_Lov(gds);
lon2r = lon2d * (M_PI / 180.0);
latin1r = GDS_Lambert_Latin1(gds) * (M_PI/180.0);
latin2r = GDS_Lambert_Latin2(gds) * (M_PI/180.0);
// fix for theta start value crossing 0 longitude
// if ((lon1r - lon2r) > 0) lon2r = lon2r + 2*M_PI;
//
// Latitude of "false origin" where scales are defined.
// It is used to estimate "reference_R", rhoref.
// Often latDr == latin1r == latin2r and non-modified code is true and works fine.
// But could be different if intersection latitudes latin1r and latin2r are different.
// Usually latDr must be latin1r <= latDr <= latin2r, other could be strange.
//
latDr = GDS_Lambert_LatD(gds) * (M_PI/180.0);
if (lon1r < 0) fatal_error("bad GDS, lon1r < 0.0","");
if ( fabs(latin1r - latin2r) < 1E-09 ) {
n = sin(latin1r);
}
else {
n = log(cos(latin1r)/cos(latin2r)) /
log(tan(M_PI_4 + latin2r/2.0) / tan(M_PI_4 + latin1r/2.0));
}
f = (cos(latin1r) * pow(tan(M_PI_4 + latin1r/2.0), n)) / n;
rho = earth_radius * f * pow(tan(M_PI_4 + lat1r/2.0),-n);
// old rhoref = earth_radius * f * pow(tan(M_PI_4 + latin1r/2.0),-n);
rhoref = earth_radius * f * pow(tan(M_PI_4 + latDr/2.0),-n);
// 2/2009 .. new code
d_lon = lon1r - lon2r;
if (d_lon > M_PI) d_lon -= 2*M_PI;
if (d_lon < -M_PI) d_lon += 2*M_PI;
theta = n * d_lon;
// 2/2009 theta = n * (lon1r - lon2r);
startx = rho * sin(theta);
starty = rhoref - rho * cos(theta);
if ((*llat = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("lambert2ll memory allocation failed","");
}
if ((*llon = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("lambert2ll memory allocation failed","");
}
lat = *llat;
lon = *llon;
/* put x[] and y[] values in lon[] and lat[] */
if (stagger(sec, nnpnts, lon, lat)) fatal_error("geo: stagger problem","");
dx = fabs(dx);
dy = fabs(dy);
#pragma omp parallel for private(j,x,y,tmp,theta,rho,lond,latd)
for (j = 0; j < nnpnts; j++) {
y = starty + lat[j]*dy;
x = startx + lon[j]*dx;
tmp = rhoref - y;
theta = atan(x / tmp);
rho = sqrt(x * x + tmp*tmp);
rho = n > 0 ? rho : -rho;
lond = lon2d + todegrees(theta/n);
latd = todegrees(2.0 * atan(pow(earth_radius * f/rho,1.0/n)) - M_PI_2);
lond = lond >= 360.0 ? lond - 360.0 : lond;
lond = lond < 0.0 ? lond + 360.0 : lond;
lon[j] = lond;
lat[j] = latd;
}
return 0;
} /* end lambert2ll() */