aboutsummaryrefslogtreecommitdiff
path: root/libcrystfel
diff options
context:
space:
mode:
authorThomas White <taw@physics.org>2012-04-02 19:29:48 +0200
committerThomas White <taw@physics.org>2012-04-05 15:14:22 +0200
commitf556bc88774d44206990557303881e3b3c320248 (patch)
treeca6a7ef08a31966e80124579da936e802d1cf6be /libcrystfel
parent89b372a8d17f3e9d5f8a4fef36cbc5aba033e639 (diff)
Improved spot prediction
Diffstat (limited to 'libcrystfel')
-rw-r--r--libcrystfel/src/geometry.c83
1 files changed, 30 insertions, 53 deletions
diff --git a/libcrystfel/src/geometry.c b/libcrystfel/src/geometry.c
index 218c0fee..0f6e4809 100644
--- a/libcrystfel/src/geometry.c
+++ b/libcrystfel/src/geometry.c
@@ -99,29 +99,6 @@ static signed int locate_peak(double x, double y, double z, double k,
}
-static double excitation_error(double xl, double yl, double zl,
- double ds, double k, double divergence,
- double tt)
-{
- double al;
- double r;
- double delta;
-
- al = M_PI_2 - asin(-zl/ds);
-
- r = ( ds * sin(al) / sin(tt) ) - k;
-
- delta = sqrt(2.0 * pow(ds, 2.0) * (1.0-cos(divergence)));
- if ( divergence > 0.0 ) {
- r += delta;
- } else {
- r -= delta;
- }
-
- return r;
-}
-
-
static double partiality(double r1, double r2, double r)
{
double q1, q2;
@@ -146,46 +123,44 @@ static Reflection *check_reflection(struct image *image,
double csx, double csy, double csz)
{
const int output = 0;
- double xl, yl, zl;
- double ds, ds_sq;
+ double xl, yl, zl, tl;
double rlow, rhigh; /* "Excitation error" */
signed int p; /* Panel number */
double xda, yda; /* Position on detector */
int close, inside;
double part; /* Partiality */
- int clamp_low = 0;
- int clamp_high = 0;
- double bandwidth = image->bw;
- double divergence = image->div;
- double lambda = image->lambda;
- double klow, kcen, khigh; /* Wavenumber */
+ int clamp_low, clamp_high;
+ double klow, khigh; /* Wavenumber */
Reflection *refl;
- double tt, psi;
+ double cet, cez;
/* "low" gives the largest Ewald sphere,
* "high" gives the smallest Ewald sphere. */
- klow = 1.0/(lambda - lambda*bandwidth/2.0);
- kcen = 1.0/lambda;
- khigh = 1.0/(lambda + lambda*bandwidth/2.0);
+ klow = 1.0/(image->lambda - image->lambda*image->bw/2.0);
+ khigh = 1.0/(image->lambda + image->lambda*image->bw/2.0);
/* Get the coordinates of the reciprocal lattice point */
xl = h*asx + k*bsx + l*csx;
yl = h*asy + k*bsy + l*csy;
zl = h*asz + k*bsz + l*csz;
- ds_sq = modulus_squared(xl, yl, zl); /* d*^2 */
- ds = sqrt(ds_sq);
+ /* If the point is looking "backscattery", reject it straight away */
+ if ( zl < -khigh/2.0 ) return NULL;
- /* Simple (fast) check to reject reflection if it's "in front" */
- psi = atan2(zl, sqrt(xl*xl + yl*yl));
- if ( psi - atan2(image->profile_radius, ds) > divergence ) return NULL;
+ tl = sqrt(xl*xl + yl*yl);
- tt = angle_between(0.0, 0.0, 1.0, xl, yl, zl+kcen);
- if ( tt > deg2rad(90.0) ) return NULL;
+ cet = -sin(image->div/2.0) * khigh;
+ cez = -cos(image->div/2.0) * khigh;
+ rhigh = khigh - distance(cet, cez, tl, zl); /* Loss of precision */
- /* Calculate excitation errors */
- rlow = excitation_error(xl, yl, zl, ds, klow, -divergence/2.0, tt);
- rhigh = excitation_error(xl, yl, zl, ds, khigh, +divergence/2.0, tt);
+ cet = sin(image->div/2.0) * klow;
+ cez = -cos(image->div/2.0) * klow;
+ rlow = klow - distance(cet, cez, tl, zl); /* Loss of precision */
+
+ if ( rlow < rhigh ) {
+ STATUS("%i %i %i\n", h, k, l);
+ return NULL;
+ }
/* Is the reciprocal lattice point close to either extreme of
* the sphere, maybe just outside the "Ewald volume"? */
@@ -204,7 +179,13 @@ static Reflection *check_reflection(struct image *image,
/* If the "lower" Ewald sphere is a long way away, use the
* position at which the Ewald sphere would just touch the
- * reflection. */
+ * reflection.
+ *
+ * The six possible combinations of clamp_{low,high} (including
+ * zero) correspond to the six situations in Table 3 of Rossmann
+ * et al. (1979).
+ */
+ clamp_low = 0; clamp_high = 0;
if ( rlow < -image->profile_radius ) {
rlow = -image->profile_radius;
clamp_low = -1;
@@ -213,7 +194,6 @@ static Reflection *check_reflection(struct image *image,
rlow = +image->profile_radius;
clamp_low = +1;
}
- /* Likewise the "higher" Ewald sphere */
if ( rhigh < -image->profile_radius ) {
rhigh = -image->profile_radius;
clamp_high = -1;
@@ -222,16 +202,13 @@ static Reflection *check_reflection(struct image *image,
rhigh = +image->profile_radius;
clamp_high = +1;
}
- assert(clamp_low <= clamp_high);
- /* The six possible combinations of clamp_{low,high} (including
- * zero) correspond to the six situations in Table 3 of Rossmann
- * et al. (1979). */
+ assert(clamp_low >= clamp_high);
/* Calculate partiality */
part = partiality(rlow, rhigh, image->profile_radius);
/* Locate peak on detector. */
- p = locate_peak(xl, yl, zl, kcen, image->det, &xda, &yda);
+ p = locate_peak(xl, yl, zl, 1.0/image->lambda, image->det, &xda, &yda);
if ( p == -1 ) return NULL;
/* Add peak to list */
@@ -276,7 +253,7 @@ RefList *find_intersections(struct image *image, UnitCell *cell)
/* We add a horrific 20% fudge factor because bandwidth, divergence
* and so on mean reflections appear beyond the largest q */
- mres = 1.2 * largest_q(image);
+ mres = largest_q(image);
hmax = mres / modulus(asx, asy, asz);
kmax = mres / modulus(bsx, bsy, bsz);