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MNEMorphMap

Namespace: MNELIB  ·  Library: MNE Library

#include <mne/mne_morph_map.h>

class MNELIB::MNEMorphMap

Morph map of one hemisphere from one subject to another.

src/examples/ex_mne_api/main.cpp
// Morph map between the registered spheres of two subjects: every vertex of "large" is a
// barycentric blend of the three corners of the "small" triangle it falls into.
const QString subjectsDir = QStringLiteral(MNE_MORPH_SUBJECTS_DIR);
FsSurface smallSphere;
FsSurface largeSphere;
FsSurface::read(subjectsDir + "/small/surf/lh.sphere.reg", smallSphere, false);
FsSurface::read(subjectsDir + "/large/surf/lh.sphere.reg", largeSphere, false);
MNEMorphMap smallToLarge = MNEMorphMap::compute(smallSphere.rr(), smallSphere.tris(), largeSphere.rr());
smallToLarge.from_subj = "small";
smallToLarge.to_subj = "large";
smallToLarge.hemi = 0;
const QString mapFile = tmp.filePath("small-large-morph.fif");
MNEMorphMap::write(mapFile, {&smallToLarge});
const auto reread = MNEMorphMap::read(mapFile, "small", "large", 0);
const Eigen::SparseMatrix<double> weights = reread->toEigen(); // 642 x 162, feeds INVLIB::SourceMorph

Public Methods​

MNEMorphMap()​

MNEMorphMap()​

operator=()​

~MNEMorphMap()​

MNEMorphMap(other)​

Copies the map including its matrix.

Parameters:

  • other : const MNEMorphMap & The map to copy.

toEigen()​

Returns the map as a matrix that takes source vertex values to destination vertices.

Returns:

  • Eigen::SparseMatrix< double > — The destination x source sparse matrix in double precision (e.g. for SourceMorph).

Static Methods​

compute(fromRr, fromTris, toRr)​

Computes the map between two registered spheres (MNE-C mne_compose_morph_maps, accurate mode; mne.surface._make_morph_map_hemi).

Both spheres are scaled to unit radius. Each destination vertex is mapped to the source triangle it falls into, among the triangles around its nearest source vertex, with barycentric weights; best holds that nearest vertex.

Parameters:

  • fromRr : const Eigen::MatrixX3f & Source sphere vertices.

  • fromTris : const Eigen::MatrixX3i & Source sphere triangles.

  • toRr : const Eigen::MatrixX3f & Destination sphere vertices.

Returns:

  • MNEMorphMap — The map (destination vertices x source vertices).

read(path, fromSubj, toSubj, hemi)​

Reads one map from a morph-map file (MNE-C load_one_morph_map).

Parameters:

  • path : const QString & A -morph.fif file.

  • fromSubj : const QString & Source subject.

  • toSubj : const QString & Destination subject.

  • hemi : int 0 for the left, 1 for the right hemisphere.

Returns:

  • std::optional< MNEMorphMap > — The map, or no value if the file has no such map.

write(path, maps)​

Writes maps as FIFFB_MNE_MORPH_MAP blocks (MNE-C mne_save_morph_map_matrices).

Parameters:

  • path : const QString & The output file.

  • maps : const QList< const MNEMorphMap * > & The maps; from_subj, to_subj and hemi identify each one.

Returns:

  • bool — True if the file was written.

Example​

Used in examples​

ex_mne_api​

MNE library: BEM surfaces, surface projection, ICP, source spaces and epochs.

src/examples/ex_mne_api/main.cpp, line 537
FsSurface largeSphere;
FsSurface::read(subjectsDir + "/small/surf/lh.sphere.reg", smallSphere, false);
FsSurface::read(subjectsDir + "/large/surf/lh.sphere.reg", largeSphere, false);
MNEMorphMap smallToLarge = MNEMorphMap::compute(smallSphere.rr(), smallSphere.tris(), largeSphere.rr());
smallToLarge.from_subj = "small";
smallToLarge.to_subj = "large";
smallToLarge.hemi = 0;
const QString mapFile = tmp.filePath("small-large-morph.fif");
MNEMorphMap::write(mapFile, {&smallToLarge});
const auto reread = MNEMorphMap::read(mapFile, "small", "large", 0);
const Eigen::SparseMatrix<double> weights = reread->toEigen(); // 642 x 162, feeds INVLIB::SourceMorph
// mne.read_morph_map("small", "large"): vertex 0 of "large" = 0.4372 * v0 + 0.3726 * v42 + 0.1902 * v51 of "small"
ok &= expect(weights.rows() == 642 && weights.cols() == 162 && std::abs(weights.coeff(0, 0) - 0.43720984) < 1e-5 && std::abs(weights.coeff(0, 42) - 0.37262118) < 1e-5 && std::abs(weights.coeff(0, 51) - 0.19016896) < 1e-5,

Authors of this file​