ref: 1b09060f468f530af2f4ef75441a40084e912e54
dir: /sys/src/cmd/scat/posn.c/
#include <u.h> #include <libc.h> #include <bio.h> #include "sky.h" void amdinv(Header *h, Angle ra, Angle dec, float mag, float col) { int i, max_iterations; float tolerance; float object_x, object_y, delta_x, delta_y, f, fx, fy, g, gx, gy; float x1, x2, x3, x4; float y1, y2, y3, y4; /* * Initialize */ max_iterations = 50; tolerance = 0.0000005; /* * Convert RA and Dec to St.coords */ traneqstd(h, ra, dec); /* * Set initial value for x,y */ object_x = h->xi/h->param[Ppltscale]; object_y = h->eta/h->param[Ppltscale]; /* * Iterate by Newtons method */ for(i = 0; i < max_iterations; i++) { /* * X plate model */ x1 = object_x; x2 = x1 * object_x; x3 = x1 * object_x; x4 = x1 * object_x; y1 = object_y; y2 = y1 * object_y; y3 = y1 * object_y; y4 = y1 * object_y; f = h->param[Pamdx1] * x1 + h->param[Pamdx2] * y1 + h->param[Pamdx3] + h->param[Pamdx4] * x2 + h->param[Pamdx5] * x1*y1 + h->param[Pamdx6] * y2 + h->param[Pamdx7] * (x2+y2) + h->param[Pamdx8] * x2*x1 + h->param[Pamdx9] * x2*y1 + h->param[Pamdx10] * x1*y2 + h->param[Pamdx11] * y3 + h->param[Pamdx12] * x1* (x2+y2) + h->param[Pamdx13] * x1 * (x2+y2) * (x2+y2) + h->param[Pamdx14] * mag + h->param[Pamdx15] * mag*mag + h->param[Pamdx16] * mag*mag*mag + h->param[Pamdx17] * mag*x1 + h->param[Pamdx18] * mag * (x2+y2) + h->param[Pamdx19] * mag*x1 * (x2+y2) + h->param[Pamdx20] * col; /* * Derivative of X model wrt x */ fx = h->param[Pamdx1] + h->param[Pamdx4] * 2*x1 + h->param[Pamdx5] * y1 + h->param[Pamdx7] * 2*x1 + h->param[Pamdx8] * 3*x2 + h->param[Pamdx9] * 2*x1*y1 + h->param[Pamdx10] * y2 + h->param[Pamdx12] * (3*x2+y2) + h->param[Pamdx13] * (5*x4 + 6*x2*y2 + y4) + h->param[Pamdx17] * mag + h->param[Pamdx18] * mag*2*x1 + h->param[Pamdx19] * mag*(3*x2+y2); /* * Derivative of X model wrt y */ fy = h->param[Pamdx2] + h->param[Pamdx5] * x1 + h->param[Pamdx6] * 2*y1 + h->param[Pamdx7] * 2*y1 + h->param[Pamdx9] * x2 + h->param[Pamdx10] * x1*2*y1 + h->param[Pamdx11] * 3*y2 + h->param[Pamdx12] * 2*x1*y1 + h->param[Pamdx13] * 4*x1*y1* (x2+y2) + h->param[Pamdx18] * mag*2*y1 + h->param[Pamdx19] * mag*2*x1*y1; /* * Y plate model */ g = h->param[Pamdy1] * y1 + h->param[Pamdy2] * x1 + h->param[Pamdy3] + h->param[Pamdy4] * y2 + h->param[Pamdy5] * y1*x1 + h->param[Pamdy6] * x2 + h->param[Pamdy7] * (x2+y2) + h->param[Pamdy8] * y3 + h->param[Pamdy9] * y2*x1 + h->param[Pamdy10] * y1*x3 + h->param[Pamdy11] * x3 + h->param[Pamdy12] * y1 * (x2+y2) + h->param[Pamdy13] * y1 * (x2+y2) * (x2+y2) + h->param[Pamdy14] * mag + h->param[Pamdy15] * mag*mag + h->param[Pamdy16] * mag*mag*mag + h->param[Pamdy17] * mag*y1 + h->param[Pamdy18] * mag * (x2+y2) + h->param[Pamdy19] * mag*y1 * (x2+y2) + h->param[Pamdy20] * col; /* * Derivative of Y model wrt x */ gx = h->param[Pamdy2] + h->param[Pamdy5] * y1 + h->param[Pamdy6] * 2*x1 + h->param[Pamdy7] * 2*x1 + h->param[Pamdy9] * y2 + h->param[Pamdy10] * y1*2*x1 + h->param[Pamdy11] * 3*x2 + h->param[Pamdy12] * 2*x1*y1 + h->param[Pamdy13] * 4*x1*y1 * (x2+y2) + h->param[Pamdy18] * mag*2*x1 + h->param[Pamdy19] * mag*y1*2*x1; /* * Derivative of Y model wrt y */ gy = h->param[Pamdy1] + h->param[Pamdy4] * 2*y1 + h->param[Pamdy5] * x1 + h->param[Pamdy7] * 2*y1 + h->param[Pamdy8] * 3*y2 + h->param[Pamdy9] * 2*y1*x1 + h->param[Pamdy10] * x2 + h->param[Pamdy12] * 3*y2 + h->param[Pamdy13] * (5*y4 + 6*x2*y2 + x4) + h->param[Pamdy17] * mag + h->param[Pamdy18] * mag*2*y1 + h->param[Pamdy19] * mag*(x2 + 3*y2); f = f - h->xi; g = g - h->eta; delta_x = (-f*gy+g*fy) / (fx*gy-fy*gx); delta_y = (-g*fx+f*gx) / (fx*gy-fy*gx); object_x = object_x + delta_x; object_y = object_y + delta_y; if((fabs(delta_x) < tolerance) && (fabs(delta_y) < tolerance)) break; } /* * Convert mm from plate center to pixels */ h->x = (h->param[Pppo3]-object_x*1000.0)/h->param[Pxpixelsz]; h->y = (h->param[Pppo6]+object_y*1000.0)/h->param[Pypixelsz]; } void ppoinv(Header *h, Angle ra, Angle dec) { /* * Convert RA and Dec to standard coords. */ traneqstd(h, ra, dec); /* * Convert st.coords from arcsec to radians */ h->xi /= ARCSECONDS_PER_RADIAN; h->eta /= ARCSECONDS_PER_RADIAN; /* * Compute PDS coordinates from solution */ h->x = h->param[Pppo1]*h->xi + h->param[Pppo2]*h->eta + h->param[Pppo3]; h->y = h->param[Pppo4]*h->xi + h->param[Pppo5]*h->eta + h->param[Pppo6]; /* * Convert x,y from microns to pixels */ h->x /= h->param[Pxpixelsz]; h->y /= h->param[Pypixelsz]; } void traneqstd(Header *h, Angle object_ra, Angle object_dec) { float div; /* * Find divisor */ div = (sin(object_dec)*sin(h->param[Ppltdec]) + cos(object_dec)*cos(h->param[Ppltdec]) * cos(object_ra - h->param[Ppltra])); /* * Compute standard coords and convert to arcsec */ h->xi = cos(object_dec) * sin(object_ra - h->param[Ppltra]) * ARCSECONDS_PER_RADIAN/div; h->eta = (sin(object_dec)*cos(h->param[Ppltdec])- cos(object_dec)*sin(h->param[Ppltdec])* cos(object_ra - h->param[Ppltra]))* ARCSECONDS_PER_RADIAN/div; } void xypos(Header *h, Angle ra, Angle dec, float mag, float col) { if (h->amdflag) { amdinv(h, ra, dec, mag, col); } else { ppoinv(h, ra, dec); } }