void sip_iwc2radec(const sip_t* sip, double x, double y, double *p_ra, double *p_dec) {
tan_iwc2radec(&(sip->wcstan), x, y, p_ra, p_dec);
}
void tpv_iwc2radec(const tpv_t* tpv, double x, double y, double *p_ra, double *p_dec) {
tan_iwc2radec(&(tpv->wcstan), x, y, p_ra, p_dec);
}
sip_t* wcs_pv2sip_header(qfits_header* hdr,
double* xy, int Nxy,
double stepsize,
double xlo, double xhi,
double ylo, double yhi,
int imageW, int imageH,
int order,
anbool forcetan,
int doshift) {
double* radec = NULL;
int rtn = -1;
tan_t tanwcs;
double x,y, px,py;
double* rddist = NULL;
int i, j;
int nx, ny;
double xstep, ystep;
sip_t* sip = NULL;
/**
From http://iraf.noao.edu/projects/mosaic/tpv.html
p = PV1_
xi' = p0 +
p1 * xi + p2 * eta + p3 * r +
p4 * xi^2 + p5 * xi * eta + p6 * eta^2 +
p7 * xi^3 + p8 * xi^2 * eta + p9 * xi * eta^2 +
p10 * eta^3 + p11 * r^3 +
p12 * xi^4 + p13 * xi^3 * eta + p14 * xi^2 * eta^2 +
p15 * xi * eta^3 + p16 * eta^4 +
p17 * xi^5 + p18 * xi^4 * eta + p19 * xi^3 * eta^2 +
p20 * xi^2 * eta^3 + p21 * xi * eta^4 + p22 * eta^5 + p23 * r^5 +
p24 * xi^6 + p25 * xi^5 * eta + p26 * xi^4 * eta^2 +
p27 * xi^3 * eta^3 + p28 * xi^2 * eta^4 + p29 * xi * eta^5 +
p30 * eta^6
p31 * xi^7 + p32 * xi^6 * eta + p33 * xi^5 * eta^2 +
p34 * xi^4 * eta^3 + p35 * xi^3 * eta^4 + p36 * xi^2 * eta^5 +
p37 * xi * eta^6 + p38 * eta^7 + p39 * r^7
p = PV2_
eta' = p0 +
p1 * eta + p2 * xi + p3 * r +
p4 * eta^2 + p5 * eta * xi + p6 * xi^2 +
p7 * eta^3 + p8 * eta^2 * xi + p9 * eta * xi^2 + p10 * xi^3 +
p11 * r^3 +
p12 * eta^4 + p13 * eta^3 * xi + p14 * eta^2 * xi^2 +
p15 * eta * xi^3 + p16 * xi^4 +
p17 * eta^5 + p18 * eta^4 * xi + p19 * eta^3 * xi^2 +
p20 * eta^2 * xi^3 + p21 * eta * xi^4 + p22 * xi^5 +
p23 * r^5 +
p24 * eta^6 + p25 * eta^5 * xi + p26 * eta^4 * xi^2 +
p27 * eta^3 * xi^3 + p28 * eta^2 * xi^4 + p29 * eta * xi^5 +
p30 * xi^6
p31 * eta^7 + p32 * eta^6 * xi + p33 * eta^5 * xi^2 +
p34 * eta^4 * xi^3 + p35 * eta^3 * xi^4 + p36 * eta^2 * xi^5 +
p37 * eta * xi^6 + p38 * xi^7 + p39 * r^7
Note the "cross-over" -- the xi' powers are in terms of xi,eta
while the eta' powers are in terms of eta,xi.
*/
// 1 x y r x2 xy y2 x3 x2y xy2 y3 r3 x4 x3y x2y2 xy3 y4
// x5 x4y x3y2 x2y3 xy4 y5 r5 x6 x5y x4y2, x3y3 x2y4 xy5 y6
// x7 x6y x5y2 x4y3 x3y4 x2y5 xy6 y7 r7
int xp[] = {
0,
1, 0, 0,
2, 1, 0,
3, 2, 1, 0, 0,
4, 3, 2, 1, 0,
5, 4, 3, 2, 1, 0, 0,
6, 5, 4, 3, 2, 1, 0,
7, 6, 5, 4, 3, 2, 1, 0, 0};
int yp[] = {
0,
0, 1, 0,
0, 1, 2,
0, 1, 2, 3, 0,
0, 1, 2, 3, 4,
0, 1, 2, 3, 4, 5, 0,
0, 1, 2, 3, 4, 5, 6,
0, 1, 2, 3, 4, 5, 6, 7, 0};
int rp[] = {
0,
0, 0, 1,
0, 0, 0,
0, 0, 0, 0, 3,
0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 5,
0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 7};
double xpows[8];
double ypows[8];
double rpows[8];
double pv1[40];
double pv2[40];
double r;
char* ct;
ct = fits_get_dupstring(hdr, "CTYPE1");
if ((ct && streq(ct, "RA---TPV")) || forcetan) {
// http://iraf.noao.edu/projects/ccdmosaic/tpv.html
logmsg("Replacing CTYPE1 = %s header with RA---TAN\n", ct);
fits_update_value(hdr, "CTYPE1", "RA---TAN");
}
ct = fits_get_dupstring(hdr, "CTYPE2");
if ((ct && streq(ct, "DEC--TPV")) || forcetan) {
logmsg("Replacing CTYPE2 = %s header with DEC--TAN\n", ct);
fits_update_value(hdr, "CTYPE2", "DEC--TAN");
}
tan_read_header(hdr, &tanwcs);
if (log_get_level() >= LOG_VERB) {
printf("Read TAN header:\n");
tan_print(&tanwcs);
}
if (imageW && (imageW != tanwcs.imagew)) {
logmsg("Overriding image width %f with user-specified %i\n",
tanwcs.imagew, imageW);
tanwcs.imagew = imageW;
}
if (imageH && (imageH != tanwcs.imageh)) {
logmsg("Overriding image height %f with user-specified %i\n",
tanwcs.imageh, imageH);
tanwcs.imageh = imageH;
}
for (i=0; i<sizeof(pv1)/sizeof(double); i++) {
char key[10];
double defaultval;
if (i == 1) {
defaultval = 1.0;
} else {
defaultval = 0.0;
}
sprintf(key, "PV1_%i", i);
pv1[i] = qfits_header_getdouble(hdr, key, defaultval);
sprintf(key, "PV2_%i", i);
pv2[i] = qfits_header_getdouble(hdr, key, defaultval);
}
// choose grid for evaluating TAN-PV WCS
if (xlo == 0 && xhi == 0) {
xlo = 1.;
xhi = tanwcs.imagew;
}
if (ylo == 0 && yhi == 0) {
ylo = 1.;
yhi = tanwcs.imageh;
}
assert(xhi >= xlo);
assert(yhi >= ylo);
if (stepsize == 0)
stepsize = 100.;
nx = MAX(2, round((xhi - xlo)/stepsize));
ny = MAX(2, round((yhi - ylo)/stepsize));
xstep = (xhi - xlo) / (double)(nx - 1);
ystep = (yhi - ylo) / (double)(ny - 1);
logverb("Stepping from x = %g to %g, steps of %g\n", xlo, xhi, xstep);
logverb("Stepping from y = %g to %g, steps of %g\n", ylo, yhi, ystep);
Nxy = nx * ny;
if (xy == NULL) {
int k = 0;
xy = malloc(Nxy * 2 * sizeof(double));
for (i=0; i<ny; i++) {
y = ylo + i*ystep;
for (j=0; j<nx; j++) {
x = xlo + j*xstep;
//if (i == 0)
//printf("x=%f\n", x);
xy[k] = x;
k++;
xy[k] = y;
k++;
}
//printf("y=%f\n", y);
}
assert(k == (Nxy*2));
}
// distorted RA,Dec
rddist = malloc(2 * Nxy * sizeof(double));
for (j=0; j<Nxy; j++) {
double ix = xy[2*j+0];
double iy = xy[2*j+1];
tan_pixelxy2iwc(&tanwcs, ix, iy, &x, &y);
// "x,y" here are most commonly known as "xi, eta".
r = sqrt(x*x + y*y);
// compute powers of x,y
xpows[0] = ypows[0] = rpows[0] = 1.0;
for (i=1; i<sizeof(xpows)/sizeof(double); i++) {
xpows[i] = xpows[i-1]*x;
ypows[i] = ypows[i-1]*y;
rpows[i] = rpows[i-1]*r;
}
px = py = 0;
for (i=0; i<sizeof(xp)/sizeof(int); i++) {
px += pv1[i] * xpows[xp[i]] * ypows[yp[i]] * rpows[rp[i]];
// here's the "cross-over" mentioned above
py += pv2[i] * ypows[xp[i]] * xpows[yp[i]] * rpows[rp[i]];
}
// Note that the PV terms *include* a linear term, so no need
// to re-add x,y to px,py.
tan_iwc2radec(&tanwcs, px, py,
rddist + 2*j, rddist + 2*j + 1);
}
sip = malloc(sizeof(sip_t));
assert(sip);
{
double* starxyz;
starxyz = malloc(3 * Nxy * sizeof(double));
for (i=0; i<Nxy; i++)
radecdegarr2xyzarr(rddist + i*2, starxyz + i*3);
memset(sip, 0, sizeof(sip_t));
rtn = fit_sip_coefficients(starxyz, xy, NULL, Nxy,
&tanwcs, order, order, sip);
assert(rtn == 0);
if (log_get_level() >= LOG_VERB) {
printf("Fit SIP:\n");
sip_print(sip);
}
// FIXME? -- use xlo,xhi,ylo,yhi here?? Not clear.
sip_compute_inverse_polynomials(sip, 0, 0, 0, 0, 0, 0);
if (log_get_level() >= LOG_VERB) {
printf("Fit SIP inverse polynomials:\n");
sip_print(sip);
}
free(starxyz);
}
free(rddist);
free(radec);
return sip;
}
