Files
Jungfraujoch/common/BraggIntegrationSettings.cpp
T
leonarski_fandClaude Opus 5 0e23fd3ab9 Bragg integration: propagate the background-estimate uncertainty, add an opt-in radial background correction
Two independent pieces in the same code path.

The background-estimate variance was never propagated. A reflection's background comes
from a finite ring of n_b pixels, so subtracting it adds var(B)/n_b per signal pixel -
sqrt(1 + n_d/n_b) = 1.109 with the shipped stencil. Both engines omitted it, which is
exactly the 1.11-1.19 gap measured between the off-ring scatter and the reported sigma.
Three lines each; it affects every dataset, not only iced ones.

The radial correction is new and OFF by default (--background-radial). The signal disk
and the background ring are concentric, so for any background LINEAR in position
<B>_ann == <B>_disk identically and a plane fit buys nothing; the leading error is the
CURVATURE of the radial background, which on a sharp ice ring reaches +26 counts on a
single reflection. Since every reflection uses the same stencil, that error is a fixed
kernel over radial offset - one short dot product per reflection and no extra pixel
reads. Validated on empty apertures before any C++: mean |bias| over 9 bands / 3
crystals 4.33 -> 0.79 counts with the scatter unchanged.

Three things it cost a battery each to learn, all now in the code:
 - the radial curve must be accumulated from CLIPPED annulus pixels, inside the clip
   pass, or it carries neighbour tails and zingers (so it is inert under --integrator
   boxsum, which has no clip pass);
 - the GPU version was a 1.8x slowdown from atomicAdd contention on a small radial
   array - staged in shared memory per block it now costs nothing measurable;
 - it is battery-NEUTRAL as a default, because the reflections whose bias it fixes are
   the ones the ice handling already excludes. Hence off by default.

CPU/GPU parity extended with two radial sections: 9002 assertions.

Also fixes a latent French-Wilson quadrature collapse: j_max = I + 8 sigma on a fixed
400-point grid degenerates to a single cell once sigma >> 50 <I>, giving F = 0.1 sqrt(sigma)
with sigmaF -> 0. Harmless today, but any sigma-inflation scheme detonates it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-06 15:44:13 +02:00

151 lines
5.0 KiB
C++

// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only
#include <cmath>
#include "BraggIntegrationSettings.h"
#include "JFJochException.h"
#define check_max(param, val, max) if ((val) > (max)) throw JFJochException(JFJochExceptionCategory::InputParameterAboveMax, param)
#define check_min(param, val, min) if ((val) < (min)) throw JFJochException(JFJochExceptionCategory::InputParameterBelowMin, param)
#define check_finite(param, val) if (!std::isfinite(val)) throw JFJochException(JFJochExceptionCategory::InputParameterInvalid, param)
BraggIntegrationSettings &BraggIntegrationSettings::R1(float input) {
check_finite("Integration radius R1", input);
check_min("Integration radius R1", input, 0.1);
check_max("Integration radius R1", input, 20.0);
r_1 = input;
return *this;
}
BraggIntegrationSettings &BraggIntegrationSettings::R2(float input) {
check_finite("Background inner radius R2", input);
check_min("Background inner radius R2", input, 0.1);
check_max("Background inner radius R2", input, 30.0);
if (input <= r_1)
throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
"Background inner radius (R2) must be larger than integration radius (R1)");
r_2 = input;
return *this;
}
BraggIntegrationSettings &BraggIntegrationSettings::R3(float input) {
check_finite("Background outer radius R3", input);
check_min("Background outer radius R3", input, 0.1);
check_max("Background outer radius R3", input, 40.0);
if (input <= r_2)
throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
"Background outer radius (R3) must be larger than background inner radius (R2)");
r_3 = input;
return *this;
}
BraggIntegrationSettings &BraggIntegrationSettings::DMinLimit_A(std::optional<float> input) {
if (input) {
check_finite("Minimum d-spacing", *input);
check_min("Minimum d-spacing", *input, 0.5);
check_max("Minimum d-spacing", *input, 100.0);
}
d_min_limit_A = input;
return *this;
}
BraggIntegrationSettings & BraggIntegrationSettings::FixedProfileRadius_recipA(std::optional<float> input) {
if (input) {
check_finite("Profile radius", input.value());
check_min("Profile radius [A^-1]", input.value(), 0.000001);
check_max("Profile radius [A^-1]", input.value(), 0.01);
}
fixed_profile_radius = input;
return *this;
}
std::optional<float> BraggIntegrationSettings::GetFixedProfileRadius_recipA() const {
return fixed_profile_radius;
}
BraggIntegrationSettings &BraggIntegrationSettings::Integrator(IntegratorMode input) {
integrator_mode = input;
return *this;
}
IntegratorMode BraggIntegrationSettings::GetIntegrator() const {
return integrator_mode;
}
float BraggIntegrationSettings::GetR1() const {
return r_1;
}
float BraggIntegrationSettings::GetR2() const {
return r_2;
}
float BraggIntegrationSettings::GetR3() const {
return r_3;
}
std::optional<float> BraggIntegrationSettings::GetDMinLimit_A() const {
return d_min_limit_A;
}
float BraggIntegrationSettings::GetMinimumSigmaInRegardsToI() const {
return minimum_sigma_in_regards_to_i;
}
BraggIntegrationSettings &BraggIntegrationSettings::BackgroundTrimFraction(float input) {
check_finite("Background trim fraction", input);
check_min("Background trim fraction", input, 0.0);
check_max("Background trim fraction", input, 0.49); // must leave a central majority after trimming
bkg_trim_fraction = input;
if (input > 0.0f)
bkg_clip_nsigma = 0.0f; // the two ring estimators are alternatives, not a stack
return *this;
}
float BraggIntegrationSettings::GetBackgroundTrimFraction() const {
return bkg_trim_fraction;
}
BraggIntegrationSettings &BraggIntegrationSettings::MaxHKL(std::optional<int> input) {
if (input) {
check_min("Maximum hkl index", *input, 1);
// The GPU predictor launches one thread per candidate, so the cost is (2n+1)^3: 511 is 1.1e9
// candidates per frame, already far past the point where prediction dominates a run.
check_max("Maximum hkl index", *input, 511);
}
max_hkl = input;
return *this;
}
std::optional<int> BraggIntegrationSettings::GetMaxHKL() const {
return max_hkl;
}
BraggIntegrationSettings &BraggIntegrationSettings::BackgroundClipNSigma(float input) {
check_finite("Background clip nsigma", input);
check_min("Background clip nsigma", input, 0.0);
bkg_clip_nsigma = input;
if (input > 0.0f)
bkg_trim_fraction = 0.0f; // the two ring estimators are alternatives, not a stack
return *this;
}
float BraggIntegrationSettings::GetBackgroundClipNSigma() const {
return bkg_clip_nsigma;
}
BraggIntegrationSettings &BraggIntegrationSettings::BackgroundRadialCorrection(bool input) {
bkg_radial_correction = input;
return *this;
}
bool BraggIntegrationSettings::IsBackgroundRadialCorrection() const {
return bkg_radial_correction;
}