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/*
* reproject.c
*
* Synthesize diffraction patterns
*
* (c) 2007 Thomas White <taw27@cam.ac.uk>
*
* dtr - Diffraction Tomography Reconstruction
*
*/
#include <stdlib.h>
#include <math.h>
#include "control.h"
#include "reflections.h"
#define MAX_IMAGE_REFLECTIONS 1024
ImageReflection *reproject_get_reflections(ImageRecord image, size_t *n, ReflectionContext *rctx) {
ImageReflection *refl;
Reflection *reflection;
int i;
double smax = 1e9;
double tilt, omega;
tilt = 2*M_PI*(image.tilt/360);
omega = 2*M_PI*(image.omega/360); /* Convert to Radians */
refl = malloc(MAX_IMAGE_REFLECTIONS*sizeof(ImageReflection));
i = 0;
reflection = rctx->reflections;
do {
double xl, yl, zl;
double nx, ny, nz;
double xt, yt, zt;
double a, b, c;
double s1, s2, s;
/* Get the coordinates of the reciprocal lattice point */
xl = reflection->x;
yl = reflection->y;
zl = reflection->z;
/* Now calculate the (normalised) incident electron wavevector */
xt = 0;
yt = - sin(tilt);
zt = - cos(tilt);
nx = xt*cos(omega) + yt*-sin(omega);
ny = xt*sin(omega) + yt*cos(omega);
nz = zt;
/* Next, solve the reprojection equation to calculate the excitation error */
a = nx*nx + ny*ny + nz*nz;
b = 2*(xl*nx + yl*ny + zl*nz - nz/image.lambda);
c = xl*xl + yl*yl + zl*zl - 2*zl/image.lambda;
s1 = (-b + sqrt(b*b-4*a*c))/(2*a);
s2 = (-b - sqrt(b*b-4*a*c))/(2*a);
if ( s1 < s2 ) s = s1; else s = s2;
/* Skip this reflection if s is large */
if ( s <= smax ) {
double xddd, yddd, zddd;
double xdd, ydd, zdd;
double xd, yd, zd;
double theta, psi;
double x, y;
/* Determine the intersection point */
xddd = xl + s*nx; yddd = yl + s*ny; zddd = zl + s*nz;
/* Invert the image->3D mapping to get the image coordinates */
xdd = xddd;
ydd = (yddd/cos(tilt) - zddd*tan(tilt)/cos(tilt))/(1+tan(tilt)*tan(tilt));
zdd = (-zddd-ydd*sin(tilt))/cos(tilt);
yd = (ydd-xdd*tan(omega))/(sin(omega)*tan(omega)+cos(omega));
xd = (xdd+yd*sin(omega))/cos(omega);
zd = zdd;
if ( image.fmode == FORMULATION_CLEN ) {
psi = atan2(-yd, xd);
theta = acos(1-zd*image.lambda);
x = image.camera_len*sin(theta)*cos(psi);
y = image.camera_len*sin(theta)*sin(psi);
x *= image.resolution;
} else if ( image.fmode == FORMULATION_PIXELSIZE ) {
x = xd / image.pixel_size;
y = yd / image.pixel_size;
} else {
fprintf(stderr, "Unrecognised formulation mode in reproject_get_reflections()\n");
return NULL;
}
/* Adjust centre */
x += image.x_centre;
y += image.y_centre;
/* Sanity check */
if ( (x>=0) && (x<image.width) && (y>=0) && (y<image.height) ) {
/* Record the reflection */
refl[i].x = x;
refl[i].y = y;
i++;
if ( i > MAX_IMAGE_REFLECTIONS ) break;
printf("Reflection %i at %i,%i\n", i, refl[i-1].x, refl[i-1].y);
} else {
fprintf(stderr, "Reflection failed sanity test\n");
}
}
reflection = reflection->next;
} while ( reflection );
*n = i;
return refl;
}
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