Files
Jungfraujoch/image_analysis/scale_merge/StillsPartialityRefine.cpp
T
leonarski_f 8a123e794d Stills: the run's rocking curve goes to _process.h5 and --mode scale merges with it; MeasureRunWidth takes the window at each reflection's resolution
--mode scale re-measured the rocking width on the stored reflections, so on any file whose frames were
predicted through the run's curve it merged with a different curve than the mx run did. The curve the
post-refinement used (formula, table, radial scale) is now carried in the EndMessage (StillsRunWidth) and
written to the master: /entry/MX/stillsRockingWidthFormula [gamma0 1/A, gamma_e rad, bandwidth sigma],
/entry/MX/stillsRadialScale, /entry/MX/stillsRockingWidthTableDstar and /entry/MX/stillsRockingWidthTable
(1/A). The reader returns it, and --mode scale passes it to the post-refinement. A file without it is
re-measured as before.

MeasureRunWidth grouped each frame's reflections by the frame's window, taken as the largest excitation
error it predicted. With a window that follows sigma(d*) that is the high-resolution window, applied to the
frame's low-resolution reflections too. Given the curve the frames were predicted through, the window is now
that curve at the reflection's own resolution; without one, the frame's largest excitation error as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015CeEGgpKdfkCTJb3YNMJcu
(cherry picked from commit 992343d0206489991880bb927efc79131134a1d9)
2026-10-26 14:09:32 +01:00

794 lines
40 KiB
C++

// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only
#include "StillsPartialityRefine.h"
#include <algorithm>
#include <array>
#include <atomic>
#include <cmath>
#include <future>
#include <thread>
#include <vector>
#include <Eigen/Dense>
#include <ceres/rotation.h>
#include "Merge.h"
#include "../../common/Logger.h"
#include "../../common/ThreadAffinity.h"
namespace {
constexpr size_t MIN_FIT_REFLECTIONS = 20;
constexpr double kRadToDeg = 180.0 / 3.14159265358979323846;
// Model error of the per-crystal scale fit, as a fraction of the predicted intensity - ScaleOnTheFly's.
constexpr double SCALE_MODEL_ERROR = 0.3;
double SafeInv(double x, double fallback) {
if (!std::isfinite(x) || x == 0.0)
return fallback;
return 1.0 / x;
}
// One accepted reflection reduced to the physical partiality fit: the base reciprocal vector q (crystal
// frame at the stored per-image orientation), the reference full intensity, the measured intensity, the
// reciprocal of the prescaling correction (the factor that turns a true intensity back into counts),
// the measured variance and its background part, and the weight the tilt is refined with.
// dist_ewald / partiality are recomputed from q under the refined tilt.
struct FitObs {
double qx, qy, qz;
double Iref;
double Iobs;
double inv_corr; // 1 / (prescaling_corr * qe_corr * flight_corr)
double sigma2;
double var_bkg;
double weight; // 1 / sqrt(variance at the current model), set with each G
};
// The variance of an observation at the model m: background, the counting noise of m and the model error.
double ModelVariance(const FitObs &o, double m) {
return o.var_bkg + std::max(0.0, m) + SCALE_MODEL_ERROR * SCALE_MODEL_ERROR * m * m;
}
double VecLen(double x, double y, double z) { return std::sqrt(x * x + y * y + z * z); }
// The rocking width sigma^2 at a reflection of resolution d* (and |q_z|, for the bandwidth term): the
// run's table where there is one - linear in d* between its shells, held beyond the outermost - else
// the three-term formula.
struct Width {
double gamma0, gamma_e, bw;
const std::vector<double> *table_dstar = nullptr, *table_s = nullptr;
double Sigma2(double dstar, double qz) const {
if (table_dstar && !table_dstar->empty()) {
const auto &x = *table_dstar;
const auto &y = *table_s;
double s = y.front();
if (dstar >= x.back())
s = y.back();
else if (dstar > x.front()) {
const size_t i = std::upper_bound(x.begin(), x.end(), dstar) - x.begin();
s = y[i - 1] + (dstar - x[i - 1]) / (x[i] - x[i - 1]) * (y[i] - y[i - 1]);
}
return s * s;
}
const double sig_ang = gamma_e * dstar;
const double sbw = bw * std::fabs(qz);
return gamma0 * gamma0 + sig_ang * sig_ang + sbw * sbw;
}
};
// Analytic partiality for a reflection whose base reciprocal vector is q, tilted by (psi_x, psi_y).
// Mirrors BraggPrediction: dist_ewald = |S| - 1/lambda with S = q_rot + S0, and
// p = exp(-dist_ewald^2 / 2 sigma^2), sigma^2 = gamma0^2 + (gamma_e*d*)^2 + (bw*|q_z|)^2 - three
// independent broadenings added in quadrature: the reciprocal-lattice point's own radius (gamma0,
// ~1/domain size, resolution-INdependent), the mosaic/divergence spread (gamma_e*d*, proportional to
// d*) and the bandwidth smear along the beam. In practice the fit below returns gamma_e ~ 0 and the
// width is essentially gamma0 - see there.
double ComputeP(double qx, double qy, double qz,
double psi_x, double psi_y,
double s0x, double s0y, double s0z, double inv_lambda,
const Width &width) {
double aa[3] = {psi_x, psi_y, 0.0};
double q[3] = {qx, qy, qz};
double qr[3];
ceres::AngleAxisRotatePoint(aa, q, qr);
const double Sx = qr[0] + s0x, Sy = qr[1] + s0y, Sz = qr[2] + s0z;
const double de = std::sqrt(Sx * Sx + Sy * Sy + Sz * Sz) - inv_lambda;
const double dstar = std::sqrt(qr[0] * qr[0] + qr[1] * qr[1] + qr[2] * qr[2]);
const double sig2 = width.Sigma2(dstar, qr[2]);
if (!(sig2 > 0.0))
return 1.0;
return std::exp(-0.5 * de * de / sig2);
}
// The prediction window cuts the rocking curve. Reflections fill a window of half-width W evenly, so
// their plain moment of de is u = W^2 / 3, and the intensity-weighted moment m of a Gaussian of width
// s cut at +-W is u * g(a), a = W / s, with g(a) = 3/a^2 (1 - 2 a phi(a) / erf(a / sqrt 2)): 1 for a
// curve much wider than the window, s^2 / u for a much narrower one. Solves g(a) = m / u for s^2 by
// bisection (g falls with a). A curve wider than the window cannot be measured through it: empty.
std::optional<double> UntruncatedVariance(double m, double u) {
auto g = [](double a) {
const double phi = std::exp(-0.5 * a * a) / std::sqrt(2.0 * 3.14159265358979323846);
return 3.0 / (a * a) * (1.0 - 2.0 * a * phi / std::erf(a / std::sqrt(2.0)));
};
const double t = m / u;
double lo = 1.0, hi = 50.0;
if (!(t < g(lo)))
return std::nullopt;
for (int i = 0; i < 60; ++i) {
const double mid = 0.5 * (lo + hi);
(g(mid) > t ? lo : hi) = mid;
}
const double a = 0.5 * (lo + hi);
return 3.0 * u / (a * a);
}
// Robust per-crystal scale G (linear in G given the model coefficients), the objective of
// ScaleOnTheFly::SolveScaleIRLS: minimise sum Cauchy_k( (G*coeff - Iobs) / sqrt(var(G*coeff)) ) over G >= 0,
// the variances re-evaluated at each step's G.
double SolveScaleIRLS(const std::vector<FitObs> &obs, const std::vector<double> &coeff, double robust_k) {
double num = 0.0, den = 0.0;
for (size_t i = 0; i < obs.size(); ++i) {
num += coeff[i] * obs[i].Iobs / obs[i].sigma2;
den += coeff[i] * coeff[i] / obs[i].sigma2;
}
if (!(den > 0.0) || !std::isfinite(num / den))
return 1.0;
double G = std::max(0.0, num / den);
const double k2 = robust_k * robust_k;
for (int iter = 0; iter < 30; ++iter) {
num = den = 0.0;
for (size_t i = 0; i < obs.size(); ++i) {
const double res = G * coeff[i] - obs[i].Iobs;
const double w = 1.0 / (ModelVariance(obs[i], G * coeff[i]) + res * res / k2);
num += w * coeff[i] * obs[i].Iobs;
den += w * coeff[i] * coeff[i];
}
if (!(den > 0.0) || !std::isfinite(num / den))
break;
const double G_prev = G;
G = std::max(0.0, num / den);
if (std::abs(G - G_prev) <= 1e-7 * std::max(G, 1.0))
break;
}
return G;
}
// The rotation by the angle-axis vector (psi_x, psi_y, 0) as a matrix (Rodrigues), so that one tilt
// is applied to all the reflections of a crystal by a matrix product each.
std::array<double, 9> TiltMatrix(double psi_x, double psi_y) {
const double theta = std::sqrt(psi_x * psi_x + psi_y * psi_y);
if (theta < 1e-15)
return {1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0};
const double kx = psi_x / theta, ky = psi_y / theta;
const double c = std::cos(theta), s = std::sin(theta), t = 1.0 - c;
return {c + t * kx * kx, t * kx * ky, s * ky,
t * kx * ky, c + t * ky * ky, -s * kx,
-s * ky, s * kx, c};
}
// ComputeP with the tilt given as its rotation matrix.
struct TiltModel {
double s0x, s0y, s0z, inv_lambda;
Width width;
double P(const std::array<double, 9> &R, const FitObs &o) const {
const double qx = R[0] * o.qx + R[1] * o.qy + R[2] * o.qz;
const double qy = R[3] * o.qx + R[4] * o.qy + R[5] * o.qz;
const double qz = R[6] * o.qx + R[7] * o.qy + R[8] * o.qz;
const double de = VecLen(qx + s0x, qy + s0y, qz + s0z) - inv_lambda;
const double sig2 = width.Sigma2(VecLen(qx, qy, qz), qz);
if (!(sig2 > 0.0))
return 1.0;
return std::exp(-0.5 * de * de / sig2);
}
};
// Refine the orientation tilt (psi_x, psi_y) holding the scale G fixed: minimise
// sum_i rho(r_i^2) / 2 + |psi / sigma_prior|^2 / 2, r_i = weight_i (G p_i(psi) Iref_i / corr_i - Iobs_i),
// with the Cauchy rho(s) = k^2 log(1 + s / k^2) - the intensity-space objective of ScaleOnTheFly, and
// the Gaussian prior a proper MAP term since r_i is already in sigma units. Levenberg-Marquardt on the
// normal equations reweighted by rho', the Jacobian by central differences, every trial tilt held inside
// the bound. Returns false when the cost cannot be evaluated, leaving psi as it came in.
bool RefineTilt(const std::vector<FitObs> &obs, const TiltModel &model, double G, double robust_k,
double inv_sigma_prior, double max_tilt, double psi[2]) {
constexpr int MAX_ITERATIONS = 25;
constexpr double STEP = 1e-7; // rad, for the central differences
const double k2 = robust_k * robust_k;
const double prior2 = inv_sigma_prior * inv_sigma_prior;
auto cost = [&](const double p[2]) {
const auto R = TiltMatrix(p[0], p[1]);
double c = 0.5 * prior2 * (p[0] * p[0] + p[1] * p[1]);
for (const auto &o: obs) {
const double r = o.weight * (G * model.P(R, o) * o.inv_corr * o.Iref - o.Iobs);
c += 0.5 * k2 * std::log1p(r * r / k2);
}
return c;
};
double current = cost(psi);
if (!std::isfinite(current))
return false;
double lambda = 1e-4;
for (int iter = 0; iter < MAX_ITERATIONS; ++iter) {
const auto R = TiltMatrix(psi[0], psi[1]);
const auto Rxp = TiltMatrix(psi[0] + STEP, psi[1]), Rxm = TiltMatrix(psi[0] - STEP, psi[1]);
const auto Ryp = TiltMatrix(psi[0], psi[1] + STEP), Rym = TiltMatrix(psi[0], psi[1] - STEP);
double A00 = prior2, A01 = 0.0, A11 = prior2;
double b0 = prior2 * psi[0], b1 = prior2 * psi[1];
for (const auto &o: obs) {
const double a = o.weight * G * o.inv_corr * o.Iref;
const double r = a * model.P(R, o) - o.weight * o.Iobs;
const double jx = a * (model.P(Rxp, o) - model.P(Rxm, o)) / (2.0 * STEP);
const double jy = a * (model.P(Ryp, o) - model.P(Rym, o)) / (2.0 * STEP);
const double w = 1.0 / (1.0 + r * r / k2); // rho'
A00 += w * jx * jx;
A01 += w * jx * jy;
A11 += w * jy * jy;
b0 += w * jx * r;
b1 += w * jy * r;
}
bool accepted = false;
double trial[2] = {psi[0], psi[1]};
double trial_cost = current;
while (lambda < 1e10) {
const double M00 = A00 * (1.0 + lambda), M11 = A11 * (1.0 + lambda);
const double det = M00 * M11 - A01 * A01;
if (!(det > 0.0))
break;
trial[0] = std::clamp(psi[0] - (M11 * b0 - A01 * b1) / det, -max_tilt, max_tilt);
trial[1] = std::clamp(psi[1] - (M00 * b1 - A01 * b0) / det, -max_tilt, max_tilt);
trial_cost = cost(trial);
if (std::isfinite(trial_cost) && trial_cost < current) {
accepted = true;
lambda = std::max(lambda / 10.0, 1e-12);
break;
}
lambda *= 10.0;
}
if (!accepted)
break;
const double step = std::hypot(trial[0] - psi[0], trial[1] - psi[1]);
const double decrease = current - trial_cost;
psi[0] = trial[0];
psi[1] = trial[1];
current = trial_cost;
if (decrease <= 1e-6 * current || step <= 1e-10)
break;
}
return true;
}
}
StillsPartialityRefine::StillsPartialityRefine(const DiffractionExperiment &x)
: experiment_(x),
hkl_key_generator_(x.GetScalingSettings().GetMergeFriedel(), x.GetSpaceGroupOrP1()),
d_min_limit_(x.GetScalingSettings().GetHighResolutionLimit_A()),
d_max_limit_(x.GetScalingSettings().GetLowResolutionLimit_A()),
min_partiality_(x.GetScalingSettings().GetMinPartiality()),
bandwidth_sigma_(x.GetBandwidthFWHM().value_or(0.0f) / 2.3548f) {}
double StillsPartialityRefine::RefineOne(IntegrationOutcome &outcome,
const std::map<HKLKey, double> &reference,
const std::optional<RunWidth> &run_width,
double radial_scale) const {
if (outcome.reflections.empty())
return 0.0;
const Coord Astar = outcome.latt.Astar();
const Coord Bstar = outcome.latt.Bstar();
const Coord Cstar = outcome.latt.Cstar();
const Coord S0 = outcome.geom.GetScatteringVector();
const double inv_lambda = 1.0 / outcome.geom.GetWavelength_A();
auto base_q = [&](const Reflection &r) {
return (Astar * static_cast<float>(r.h) + Bstar * static_cast<float>(r.k)
+ Cstar * static_cast<float>(r.l)) * static_cast<float>(radial_scale);
};
// Collect the reflections that constrain the fit (accepted, non-ice, finite, present in the reference).
std::vector<FitObs> obs;
obs.reserve(outcome.reflections.size());
// Moments of the excitation error against resolution: de^2 ~ gamma0^2 + gamma_e^2 * d*^2, fitted per
// crystal by ordinary least squares on (d*^2, de^2). Both components come out of the data.
double m_n = 0.0, m_x = 0.0, m_xx = 0.0, m_y = 0.0, m_xy = 0.0;
size_t n_de = 0;
for (const Reflection &r: outcome.reflections) {
if (r.on_ice_ring || !AcceptReflection(r, d_min_limit_, d_max_limit_))
continue;
if (!std::isfinite(r.I) || !std::isfinite(r.sigma) || r.sigma <= 0.0f)
continue;
const auto it = reference.find(hkl_key_generator_(r));
if (it == reference.end() || !std::isfinite(it->second))
continue;
const Coord q = base_q(r);
obs.push_back(FitObs{
.qx = q.x, .qy = q.y, .qz = q.z,
.Iref = it->second,
.Iobs = static_cast<double>(r.I),
.inv_corr = SafeInv(r.prescaling_corr * r.qe_corr * r.flight_corr, 1.0),
.sigma2 = static_cast<double>(r.sigma) * r.sigma,
.var_bkg = std::isfinite(r.var_bkg) && r.var_bkg > 0.0f ? r.var_bkg : static_cast<double>(r.sigma) * r.sigma,
.weight = SafeInv(r.sigma, 1.0),
});
// Excitation error at the stored orientation (psi = 0), collected as the moments of de^2 against
// d*^2, so BOTH width components are fitted rather than one being forced to zero. Forcing the
// width to be purely angular (gamma0 = 0) pins it to the high-resolution edge - it is fitted over
// a d*^2-dense population - and it then collapses at low d*, giving p ~ 0 for reflections that
// were plainly recorded, which inflated the merged low-resolution intensity scale ~3.6x.
const double dstar = VecLen(q.x, q.y, q.z);
const double de0 = VecLen(q.x + S0.x, q.y + S0.y, q.z + S0.z) - inv_lambda;
if (dstar > 1e-9) {
const double x = dstar * dstar, y = de0 * de0;
m_n += 1.0;
m_x += x;
m_xx += x * x;
m_y += y;
m_xy += x * y;
++n_de;
}
}
if (obs.size() < MIN_FIT_REFLECTIONS || n_de == 0)
return 0.0;
// Without the run's measured width (too few reflections in the run to measure it), the width comes
// from this crystal's own reflections. Solve the 2x2 normal equations for de^2 = A + B d*^2. A degenerate spread in d* (all reflections in
// one shell) leaves B undetermined, so fall back to the pure angular width there; a negative fitted
// component is unphysical and is clamped to zero, which reduces to the previous model.
//
// Measured outcome, worth knowing before touching this: the fit does NOT split the width between the
// two terms - it returns gamma0 ~ 4e-4 1/A and gamma_e ~ 0 (their cross-over sits at d = 0.3 A, far
// outside any measured range), i.e. a width constant in the LINEAR Ewald distance. That is
// structural, not a fluke: prediction accepts reflections on a fixed linear |dist_ewald| cutoff, so
// the accepted population's de^2 is flat in d*^2 by construction and the slope is genuinely ~0. The
// truncated population cannot constrain an angular term, and its width is the window's, not the
// crystal's - which is why the run's measured width is used wherever there is one.
const double det = m_n * m_xx - m_x * m_x;
double A = 0.0, B = 0.0;
if (std::fabs(det) > 1e-30) {
A = (m_xx * m_y - m_x * m_xy) / det;
B = (m_n * m_xy - m_x * m_y) / det;
} else {
B = m_x > 0.0 ? m_y / m_x : 0.0;
}
double gamma0 = std::sqrt(std::max(0.0, A));
const double gamma_e_fit = std::max(std::sqrt(std::max(0.0, B)), 1e-9);
double gamma_e = settings_.gamma_e > 0.0 ? settings_.gamma_e : gamma_e_fit;
double bw = bandwidth_sigma_;
if (run_width) {
gamma0 = run_width->gamma0;
gamma_e = std::max(run_width->gamma_e, 1e-9);
bw = run_width->bandwidth_sigma;
}
const Width width{.gamma0 = gamma0, .gamma_e = gamma_e, .bw = bw,
.table_dstar = run_width ? &run_width->table_dstar : nullptr,
.table_s = run_width ? &run_width->table_s : nullptr};
double psi[2] = {0.0, 0.0};
double G = 1.0;
const TiltModel model{.s0x = S0.x, .s0y = S0.y, .s0z = S0.z, .inv_lambda = inv_lambda,
.width = width};
const bool refine_tilt = obs.size() >= settings_.min_reflections;
const int inner = refine_tilt ? settings_.inner_iterations : 1;
for (int it = 0; it < inner; ++it) {
// (1) Solve G given the current partialities, and weight the tilt fit by the variances at that model.
std::vector<double> coeff(obs.size());
for (size_t j = 0; j < obs.size(); ++j) {
const double p = ComputeP(obs[j].qx, obs[j].qy, obs[j].qz, psi[0], psi[1],
S0.x, S0.y, S0.z, inv_lambda, width);
coeff[j] = p * obs[j].inv_corr * obs[j].Iref;
}
G = SolveScaleIRLS(obs, coeff, settings_.robust_k);
if (!(G > 0.0) || !std::isfinite(G))
return 0.0;
for (size_t j = 0; j < obs.size(); ++j)
obs[j].weight = 1.0 / std::sqrt(ModelVariance(obs[j], G * coeff[j]));
if (!refine_tilt)
break;
// (2) Refine the tilt holding G fixed. A cost that cannot be evaluated keeps the tilt this crystal
// came in with and stops refining it - G alone is still a usable model.
const double inv_sigma_prior = settings_.prior_sigma_deg > 0.0 ? kRadToDeg / settings_.prior_sigma_deg : 0.0;
if (!RefineTilt(obs, model, G, settings_.robust_k, inv_sigma_prior, settings_.max_tilt_rad, psi))
break;
}
// Write the refined partiality + scale correction onto every reflection of the crystal (not only the
// fit subset), so the merge sees a consistent model. image_scale_corr = prescaling_corr * qe_corr * flight_corr /
// (partiality * G), the same composition ScaleOnTheFly writes.
for (auto &r: outcome.reflections) {
const Coord q = base_q(r);
const double p = ComputeP(q.x, q.y, q.z, psi[0], psi[1], S0.x, S0.y, S0.z, inv_lambda, width);
r.partiality = static_cast<float>(p);
const float corr = r.prescaling_corr * r.qe_corr * r.flight_corr;
const double denom = p * G;
r.image_scale_corr = (std::isfinite(corr) && std::isfinite(denom) && denom > 0.0)
? static_cast<float>(corr / denom)
: NAN;
}
outcome.image_scale_g = static_cast<float>(G);
// The corrections just changed, so the CC that ScaleOnTheFly measured no longer describes them.
// Refresh it here: it is reported per image and --min-image-cc drops images by it, so it has to be
// the CC of the data that is actually merged.
const auto [cc, cc_n] = ImageReferenceCC(outcome.reflections, reference, hkl_key_generator_,
d_min_limit_, d_max_limit_, min_partiality_);
outcome.image_scale_cc = cc;
outcome.image_scale_cc_n = cc_n;
const double tilt_deg = std::sqrt(psi[0] * psi[0] + psi[1] * psi[1]) * kRadToDeg;
return tilt_deg;
}
double StillsPartialityRefine::MeasureRadialScale(const std::vector<IntegrationOutcome> &outcomes,
const std::optional<UnitCell> &reference_cell,
double radial_scale) const {
// A scale of the reciprocal lattice - a wavelength, or a cell, a little off - leaves every spot where
// it was (positions fix only lambda d*), but moves each reflection's excitation error by
// eps lambda d*^2 / 2 for q -> (1 + eps) q, so the run's rocking curve sits off zero by an amount
// growing as d*^2. The prediction window is symmetric in de, so the intensity-weighted mean de of a
// shell is that offset, and a line through the origin in lambda d*^2 / 2 gives eps. A window that cuts
// an off-centre curve pulls the mean toward zero, so the caller iterates from the scale found.
const auto &indexing = experiment_.GetIndexingSettings();
struct Point { double x, de, w; };
std::vector<Point> pts;
double max_x = 0.0;
for (const auto &o: outcomes) {
if (!o.image_scale_g || !(*o.image_scale_g > 0.0))
continue;
if (reference_cell && !o.latt.GetUnitCell().is_close(*reference_cell, indexing.GetUnitCellDistTolerance(),
indexing.GetUnitCellAngleTolerance_deg()))
continue;
const Coord S0 = o.geom.GetScatteringVector();
const double inv_lambda = 1.0 / o.geom.GetWavelength_A();
for (const auto &r: o.reflections) {
if (r.on_ice_ring || !AcceptReflection(r, d_min_limit_, d_max_limit_) || !(r.d > 0.0f))
continue;
const double w = r.I * r.prescaling_corr * r.qe_corr * r.flight_corr / *o.image_scale_g;
if (!std::isfinite(w))
continue;
const Coord q = (o.latt.Astar() * static_cast<float>(r.h) + o.latt.Bstar() * static_cast<float>(r.k)
+ o.latt.Cstar() * static_cast<float>(r.l)) * static_cast<float>(radial_scale);
const double x = 0.5 / (inv_lambda * r.d * r.d);
pts.push_back({x, VecLen(q.x + S0.x, q.y + S0.y, q.z + S0.z) - inv_lambda, w});
max_x = std::max(max_x, x);
}
}
constexpr int N_SHELLS = 8;
if (pts.size() < 100 * N_SHELLS)
return radial_scale;
std::array<double, N_SHELLS> sw{}, swde{}, swx{};
for (const auto &p: pts) {
const int b = std::min(N_SHELLS - 1, static_cast<int>(p.x / max_x * N_SHELLS));
sw[b] += p.w;
swde[b] += p.w * p.de;
swx[b] += p.w * p.x;
}
double sxy = 0.0, sxx = 0.0;
for (int b = 0; b < N_SHELLS; ++b) {
if (!(sw[b] > 0.0))
continue;
const double x = swx[b] / sw[b], y = swde[b] / sw[b];
sxy += sw[b] * x * y;
sxx += sw[b] * x * x;
}
if (!(sxx > 0.0) || !std::isfinite(sxy))
return radial_scale;
// the slope is eps, removed by scaling q by (1 - eps)
return radial_scale * (1.0 - sxy / sxx);
}
std::optional<StillsPartialityRefine::RunWidth> StillsPartialityRefine::MeasureRunWidth(
const std::vector<IntegrationOutcome> &outcomes, const std::optional<UnitCell> &reference_cell,
double radial_scale, const RunWidth *window_width) const {
// The rocking width measured on the crystals rather than on the prediction window. A lattice point
// sits anywhere across the window with equal likelihood, while what it records is I_full * p(de), so
// the intensity-weighted second moment of the excitation error, sum I de^2 / sum I, is the width s^2
// of a Gaussian p - corrected for the window cutting the curve's tails (UntruncatedVariance). The
// plain moment of de over the predicted reflections, which the per-crystal fit in RefineOne uses, is
// instead the window's own (W^2 / 3). Measured in shells of d*^2 over the whole run, where the
// intensities of thousands of crystals average out, and fitted as s^2 = gamma0^2 + gamma_e^2 d*^2 +
// (bandwidth_sigma lambda d*^2 / 2)^2.
//
// Each frame predicts through a window of its own (twice its profile radius), and these differ by an
// order of magnitude within a run. Pooled, the frames with the widest windows decide both moments, and
// the correction then reads their window: on a run whose windows are mostly narrower than the curve at
// high resolution, the pooled measurement came out as the window at every resolution, a width constant
// in d* that is several times too wide at low resolution. So within a shell the frames are taken in
// WINDOW_GROUPS groups of similar window, each measured against its own, and the shell's width is the
// median of the groups whose curve is narrower than their window; a shell where no group can see the
// curve is left out.
//
// A frame's window is the largest excitation error it predicted where it predicted through one width.
// Predicted through the run's width (window_width), the window is its formula at the reflection's own
// resolution: the frame's largest excitation error is then the high-resolution window, and taken as the
// window of its low-resolution reflections it put them in the wrong group.
const auto &indexing = experiment_.GetIndexingSettings();
struct Point { double x, de2, w, var_w, window; };
std::vector<Point> pts;
for (const auto &o: outcomes) {
if (!o.image_scale_g || !(*o.image_scale_g > 0.0))
continue;
if (reference_cell && !o.latt.GetUnitCell().is_close(*reference_cell, indexing.GetUnitCellDistTolerance(),
indexing.GetUnitCellAngleTolerance_deg()))
continue;
float frame_window = 0.0f; // the largest excitation error the frame predicted
for (const auto &r: o.reflections)
if (std::isfinite(r.dist_ewald))
frame_window = std::max(frame_window, std::fabs(r.dist_ewald));
for (const auto &r: o.reflections) {
if (r.on_ice_ring || !AcceptReflection(r, d_min_limit_, d_max_limit_))
continue;
const double corr = r.prescaling_corr * r.qe_corr * r.flight_corr / *o.image_scale_g;
const double w = r.I * corr, sigma_w = r.sigma * corr;
if (!std::isfinite(w) || !std::isfinite(sigma_w) || !std::isfinite(r.dist_ewald) || !(r.d > 0.0f))
continue;
// The excitation error the window was cut in is the prediction's; the curve's is taken at the
// run's radial scale (MeasureRadialScale), recomputed from the lattice when that is not one.
double de = r.dist_ewald;
if (radial_scale != 1.0) {
const Coord q = (o.latt.Astar() * static_cast<float>(r.h) + o.latt.Bstar() * static_cast<float>(r.k)
+ o.latt.Cstar() * static_cast<float>(r.l)) * static_cast<float>(radial_scale);
const Coord S0 = o.geom.GetScatteringVector();
de = VecLen(q.x + S0.x, q.y + S0.y, q.z + S0.z) - 1.0 / o.geom.GetWavelength_A();
}
double window = frame_window;
if (window_width) {
// the formula at the reflection's d*, its bandwidth term at |q_z| = lambda d*^2 / 2
const double dstar = 1.0 / r.d;
const double a = window_width->gamma_e * dstar;
const double b = window_width->bandwidth_sigma * o.geom.GetWavelength_A() * dstar * dstar / 2.0;
window = std::sqrt(window_width->gamma0 * window_width->gamma0 + a * a + b * b);
}
pts.push_back({1.0 / (static_cast<double>(r.d) * r.d), de * de, w, sigma_w * sigma_w, window});
}
}
constexpr size_t N_SHELLS = 8;
constexpr size_t WINDOW_GROUPS = 4;
if (pts.size() < 100 * N_SHELLS)
return std::nullopt;
std::sort(pts.begin(), pts.end(), [](const Point &a, const Point &b) { return a.x < b.x; });
Logger logger("StillsPartialityRefine");
// A group's moment is no better than the summed intensity it is weighted by, so a group is used only
// where that sum is measured to 10 % (sum I / sigma(sum I) >= 10): beyond the diffraction limit the
// sum is noise and can even be negative, and says nothing about the width.
constexpr double MIN_SHELL_SIGNAL = 10.0;
// The width of the points [lo, hi) of pts (sorted by d*): the median of the window groups' widths.
auto shell_width = [&](size_t lo, size_t hi) -> std::optional<double> {
std::vector<Point> shell(pts.begin() + lo, pts.begin() + hi);
std::sort(shell.begin(), shell.end(), [](const Point &a, const Point &b) { return a.window < b.window; });
std::vector<double> widths;
for (size_t g = 0; g < WINDOW_GROUPS; ++g) {
const size_t glo = g * shell.size() / WINDOW_GROUPS, ghi = (g + 1) * shell.size() / WINDOW_GROUPS;
double sw = 0.0, svar = 0.0, swde2 = 0.0, sde2 = 0.0;
for (size_t i = glo; i < ghi; ++i) {
sw += shell[i].w;
svar += shell[i].var_w;
swde2 += shell[i].w * shell[i].de2;
sde2 += shell[i].de2;
}
if (!(sw >= MIN_SHELL_SIGNAL * std::sqrt(svar)) || !(swde2 > 0.0))
continue;
if (const auto v = UntruncatedVariance(swde2 / sw, sde2 / static_cast<double>(ghi - glo)))
widths.push_back(*v);
}
if (widths.empty())
return std::nullopt;
std::sort(widths.begin(), widths.end());
const size_t m = widths.size();
return m % 2 ? widths[m / 2] : 0.5 * (widths[m / 2 - 1] + widths[m / 2]);
};
// For the three-term formula (the prediction window): shells of equal count in d*^2.
std::vector<double> sx, sy;
for (size_t k = 0; k < N_SHELLS; ++k) {
const size_t lo = k * pts.size() / N_SHELLS, hi = (k + 1) * pts.size() / N_SHELLS;
const auto y = shell_width(lo, hi);
if (!y)
continue;
double sumx = 0.0;
for (size_t i = lo; i < hi; ++i)
sumx += pts[i].x;
const double x = sumx / static_cast<double>(hi - lo);
sx.push_back(x);
sy.push_back(*y);
logger.Debug("Stills rocking width at d = {:.2f} A: {:.2e} 1/A ({:.3f} deg)",
1.0 / std::sqrt(x), std::sqrt(*y), std::sqrt(*y / x) * kRadToDeg);
}
// For the partiality: shells of equal width in d*, kept as a table. Equal-count shells crowd where
// the reflections are - on a run predicting ~1000 reflections a frame, all eight sat at 3.8-1.8 A, so
// the low-resolution width was the formula's extrapolation, and the three-term fit flipped between
// forms with the number of frames (to a pure bandwidth at 50k frames). Measured where it is used and
// interpolated, the width needs no form. A wider curve at finer resolution is the physics (every term
// grows with d*), so the table is made non-decreasing (pool adjacent violators, weighted by the
// shells' summed signal).
std::vector<double> table_dstar, table_s, table_weight;
{
const double lo_d = std::sqrt(pts.front().x), hi_d = std::sqrt(pts.back().x);
size_t lo = 0;
for (size_t k = 0; k < N_SHELLS; ++k) {
const double edge = lo_d + (hi_d - lo_d) * static_cast<double>(k + 1) / N_SHELLS;
size_t hi = lo;
while (hi < pts.size() && (k + 1 == N_SHELLS || std::sqrt(pts[hi].x) < edge))
++hi;
double sw = 0.0, svar = 0.0, sds = 0.0;
for (size_t i = lo; i < hi; ++i) {
sw += pts[i].w;
svar += pts[i].var_w;
sds += std::sqrt(pts[i].x);
}
if (hi - lo >= 400 && sw >= MIN_SHELL_SIGNAL * std::sqrt(svar))
if (const auto y = shell_width(lo, hi)) {
table_dstar.push_back(sds / static_cast<double>(hi - lo));
table_s.push_back(std::sqrt(*y));
table_weight.push_back(sw / std::sqrt(svar));
}
lo = hi;
}
std::vector<double> block_s, block_w;
std::vector<size_t> block_n;
for (size_t i = 0; i < table_s.size(); ++i) {
block_s.push_back(table_s[i]);
block_w.push_back(table_weight[i]);
block_n.push_back(1);
while (block_s.size() > 1 && block_s[block_s.size() - 2] > block_s.back()) {
const size_t j = block_s.size() - 2;
block_s[j] = (block_s[j] * block_w[j] + block_s.back() * block_w.back()) / (block_w[j] + block_w.back());
block_w[j] += block_w.back();
block_n[j] += block_n.back();
block_s.pop_back();
block_w.pop_back();
block_n.pop_back();
}
}
table_s.clear();
for (size_t j = 0; j < block_s.size(); ++j)
table_s.insert(table_s.end(), block_n[j], block_s[j]);
if (table_dstar.size() < 3) {
table_dstar.clear();
table_s.clear();
}
}
if (sx.size() < 3)
return std::nullopt;
// Least squares for s^2 = A + B d*^2 + C d*^4 over the shells. Every term is a variance, so a negative
// one is unphysical: of the fits on each subset of the three terms, the best with none negative is kept.
std::array<double, 3> best{};
double best_residual = INFINITY;
for (int mask = 1; mask < 8; ++mask) {
std::vector<int> terms;
for (int t = 0; t < 3; ++t)
if (mask & (1 << t))
terms.push_back(t);
const int m = static_cast<int>(terms.size());
Eigen::MatrixXd M = Eigen::MatrixXd::Zero(m, m);
Eigen::VectorXd v = Eigen::VectorXd::Zero(m);
for (size_t k = 0; k < sx.size(); ++k)
for (int i = 0; i < m; ++i) {
const double fi = std::pow(sx[k], terms[i]);
v(i) += fi * sy[k];
for (int j = 0; j < m; ++j)
M(i, j) += fi * std::pow(sx[k], terms[j]);
}
const Eigen::VectorXd c = M.ldlt().solve(v);
if (!c.allFinite() || (c.array() < 0.0).any())
continue;
std::array<double, 3> coef{};
for (int i = 0; i < m; ++i)
coef[terms[i]] = c(i);
double residual = 0.0;
for (size_t k = 0; k < sx.size(); ++k) {
const double r = sy[k] - coef[0] - coef[1] * sx[k] - coef[2] * sx[k] * sx[k];
residual += r * r;
}
if (residual < best_residual) {
best_residual = residual;
best = coef;
}
}
if (!std::isfinite(best_residual) || !(best[0] + best[1] + best[2] > 0.0))
return std::nullopt;
// The d*^4 term is a bandwidth: its radial smear bw |q_z|, with |q_z| = lambda d*^2 / 2 on the sphere.
const RunWidth width{.gamma0 = std::sqrt(best[0]), .gamma_e = std::sqrt(best[1]),
.bandwidth_sigma = 2.0 * std::sqrt(best[2]) / experiment_.GetWavelength_A(),
.radial_scale = radial_scale, .table_dstar = table_dstar, .table_s = table_s};
logger.Info("Stills rocking width measured: {:.2e} 1/A + {:.3f} deg angular + {:.4f} bandwidth (FWHM)",
width.gamma0, width.gamma_e * kRadToDeg, width.bandwidth_sigma * 2.3548);
std::string table;
for (size_t i = 0; i < table_dstar.size(); ++i)
table += fmt::format(" {:.2f} A {:.2e}", 1.0 / table_dstar[i], table_s[i]);
logger.Info("Stills rocking width for the partiality, against resolution (1/A):{}",
table.empty() ? " none, the formula is used" : table);
return width;
}
double StillsPartialityRefine::Run(std::vector<IntegrationOutcome> &outcomes, size_t nthreads,
const std::optional<UnitCell> &reference_cell,
const std::optional<RunWidth> &given_width,
std::optional<RunWidth> *used_width) const {
const auto &indexing = experiment_.GetIndexingSettings();
auto merged_crystal = [&](const IntegrationOutcome &o) {
return !reference_cell || o.latt.GetUnitCell().is_close(*reference_cell,
indexing.GetUnitCellDistTolerance(),
indexing.GetUnitCellAngleTolerance_deg());
};
if (nthreads == 0)
nthreads = AvailableCpus();
nthreads = std::max<size_t>(1, nthreads);
double last_mean_tilt = 0.0;
// Where the frames were predicted through a curve measured before the image pass, the partialities use
// that same curve. Measured again here, through windows that follow it, the width reads narrower at low
// resolution (its constant term falls to about zero), and the merge it gave moved R-free against the
// models by up to +-0.015 per run in both directions, where the one curve moved it by at most +0.008.
std::optional<RunWidth> run_width = given_width;
if (!run_width) {
double radial_scale = 1.0;
for (int i = 0; i < 3; ++i)
radial_scale = MeasureRadialScale(outcomes, reference_cell, radial_scale);
Logger("StillsPartialityRefine").Info("Stills rocking curve centre: reciprocal lattice scaled by {:+.2e}",
radial_scale - 1.0);
run_width = MeasureRunWidth(outcomes, reference_cell, radial_scale);
}
const double radial_scale = run_width ? run_width->radial_scale : 1.0;
if (used_width)
*used_width = run_width;
for (int outer = 0; outer < settings_.outer_iterations; ++outer) {
// Reference full intensities from the current corrections.
const std::vector<MergedReflection> merged = MergeAll(experiment_, outcomes, nthreads, reference_cell);
std::map<HKLKey, double> reference;
for (const auto &m: merged)
reference[hkl_key_generator_(m)] = m.I;
std::atomic<double> tilt_sum{0.0};
std::atomic<size_t> tilt_n{0};
std::atomic<size_t> next{0};
auto worker = [&]() {
size_t i = next.fetch_add(1);
while (i < outcomes.size()) {
const double t = merged_crystal(outcomes[i]) ? RefineOne(outcomes[i], reference, run_width, radial_scale) : 0.0;
if (t > 0.0) {
double prev = tilt_sum.load();
while (!tilt_sum.compare_exchange_weak(prev, prev + t)) {}
tilt_n.fetch_add(1);
}
i = next.fetch_add(1);
}
};
const size_t nt = std::min(nthreads, std::max<size_t>(1, outcomes.size()));
if (nt <= 1) {
worker();
} else {
std::vector<std::future<void>> futures;
futures.reserve(nt);
for (size_t t = 0; t < nt; ++t)
futures.emplace_back(std::async(std::launch::async, worker));
for (auto &f: futures)
f.get();
}
last_mean_tilt = tilt_n > 0 ? tilt_sum.load() / static_cast<double>(tilt_n.load()) : 0.0;
}
return last_mean_tilt;
}