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HpiFitResult

Namespace: INVLIB  ·  Library: Inverse Library

#include <inv/inv_hpi_fit.h>

struct INVLIB::HpiFitResult

The struct specifing all data needed to perform coil-wise fitting.

Complete HPI fit output: per-coil dipole parameters, head-to-device transform, fit error, and head movement distance

src/examples/ex_inv_hpi/main.cpp
InvHpiDataUpdater updater(info); // good MEG channels, their sensors and the digitised coil positions
updater.prepareDataAndProjectors(segment, MatrixXd::Identity(info->nchan, info->nchan));
// The coil frequencies are known but not their order; the first fit with bOrderFrequencies finds it.
const InvHpiModelParameters model(QVector<int>({154, 158, 161, 166}), info->sfreq, info->linefreq, true);
InvHpiFit hpi(updater.getSensors());
HpiFitResult fit;
hpi.fit(updater.getProjectedData(), updater.getProjectors(), model, updater.getHpiDigitizer(), true, fit);

Example​

Used in examples​

ex_dsp_rt​

DSP real-time workers: averaging, covariance, noise spectrum, connectivity, HPI fitting and inverse operators.

src/examples/ex_dsp_rt/main.cpp, line 294
RtHpiWorker hpiWorker(updater.getSensors());
HpiFitResult workerFit;
QObject::connect(&hpiWorker, &RtHpiWorker::resultReady, [&](const HpiFitResult& fit) { workerFit = fit; });
hpiWorker.doWork(updater.getProjectedData(), updater.getProjectors(), model, updater.getHpiDigitizer());
HpiFitResult direct;
InvHpiFit(updater.getSensors()).fit(updater.getProjectedData(), updater.getProjectors(), model, updater.getHpiDigitizer(), direct);
ok &= expect(workerFit.GoF.size() == 4 && workerFit.GoF.minCoeff() > 0.98 && workerFit.devHeadTrans.trans.isApprox(direct.devHeadTrans.trans, 1e-6f),
             QString("RtHpiWorker fits 4 coils (GoF >= %1) like InvHpiFit").arg(workerFit.GoF.size() ? workerFit.GoF.minCoeff() : 0.0, 0, 'f', 4));

ex_hpiFit​

Example for cHPI fitting on raw data with SSP. The result is written to a .txt file for comparison with MaxFilter's .pos file.

src/examples/ex_hpiFit/main.cpp, line 207
HpiFitResult hpiFitResult;
HPI.fit(matProjectedData, matPreparedProjectors, hpiModelParameters, matCoilsHead, true, hpiFitResult);
hpiModelParameters = InvHpiModelParameters(hpiFitResult.hpiFreqs,
                                           pFiffInfo->sfreq,
                                           pFiffInfo->linefreq,
                                           bFast);

ex_inv_hpi​

Inverse library: continuous head position (HPI) fitting.

src/examples/ex_inv_hpi/main.cpp, line 108
// The coil frequencies are known but not their order; the first fit with bOrderFrequencies finds it.
const InvHpiModelParameters model(QVector<int>({154, 158, 161, 166}), info->sfreq, info->linefreq, true);
InvHpiFit hpi(updater.getSensors());
HpiFitResult fit;
hpi.fit(updater.getProjectedData(), updater.getProjectors(), model, updater.getHpiDigitizer(), true, fit);
// MaxFilter head position at t = 0: translation (-0.814, -11.046, 53.572) mm. One 200 ms window, so allow 1 mm
// (test_hpiFit_integration holds the mean over the whole recording to 0.3 mm).
MatrixXd maxfilter;
IOUtils::read_eigen_matrix(maxfilter, data + "/Result/ref_hpiFit_pos.txt");
const Vector3d translation = fit.devHeadTrans.trans.block<3, 1>(0, 3).cast<double>();
const Vector3d reference = maxfilter.block<1, 3>(0, 4).transpose();
ok &= expect(fit.hpiFreqs == QVector<int>({166, 154, 161, 158}) && fit.GoF.minCoeff() > 0.98 && (translation - reference).norm() < 0.001,
             QString("InvHpiDataUpdater/InvHpiModelParameters/InvHpiFit: coils ordered 166/154/161/158 Hz, head position within %1 mm of MaxFilter")

Authors of this file​