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MNEProjectToSurface

Namespace: MNELIB  ·  Library: MNE Library

#include <mne/mne_project_to_surface.h>

class MNELIB::MNEProjectToSurface

Description of what this class is intended to do (in detail).

Projects 3-D points onto a triangulated surface mesh and returns nearest vertices and distances

src/examples/ex_mne_api/main.cpp
MNEProjectToSurface projector(innerSkull);
MatrixXf points(2, 3);
points << 0.0f, 0.0f, 0.12f, 0.05f, 0.01f, 0.03f; // one point outside, one inside the skull
MatrixXf onSurface;
VectorXi triangle;
VectorXf distance;
projector.find_closest_on_surface(points, points.rows(), onSurface, triangle, distance);

Public Methods​

MNEProjectToSurface()​

Constructs a MNEProjectToSurface object.

MNEProjectToSurface(p_MNEBemSurf)​

Constructs a MNEProjectToSurface with the data of a MNEBemSurface object.

Build a projector that snaps points onto the triangulation of p_MNEBemSurf.

Parameters:

find_closest_on_surface(r, np, rTri, nearest, dist)​

Projects a set of points r on the FsSurface.

Project a set of points onto the surface and return the nearest triangle and signed distance per point.

Parameters:

  • r : const Eigen::MatrixXf & Set of pionts, which are to be projectied.

  • np : const int number of points.

  • rTri : Eigen::MatrixXf & set of points on the surface.

  • nearest : Eigen::VectorXi & Triangle of the new point.

  • dist : Eigen::VectorXf & Distance between r and rTri.

Returns:

  • bool — true if succeeded, false otherwise.

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 155
MNEProjectToSurface projector(innerSkull);
MatrixXf points(2, 3);
points << 0.0f, 0.0f, 0.12f, 0.05f, 0.01f, 0.03f; // one point outside, one inside the skull
MatrixXf onSurface;
VectorXi triangle;
VectorXf distance;
projector.find_closest_on_surface(points, points.rows(), onSurface, triangle, distance);
// Exact point-to-triangle distance over all 5120 triangles (numpy on mne.read_bem_surfaces):
// triangle 1037 at 14.6163 mm, and 11.5561 mm on the edge shared by triangles 3143 and 3172.
// For the first point mne's _project_onto_surface returns a point on the plane of triangle 1038
// but outside the triangle (barycentric weights 1.2 and -0.39), so it is not on the surface.
ok &= expect(triangle(0) == 1037 && (triangle(1) == 3143 || triangle(1) == 3172) && (onSurface.row(0) - RowVector3f(-5.97378269e-05f, 1.14249234e-03f, 0.105428493f)).norm() < 1e-6f && (onSurface.row(1) - RowVector3f(0.060674f, 0.01416721f, 0.02850214f)).norm() < 1e-6f && near(distance(0), 0.014616349831736736, 1e-5) && near(distance(1), 0.011556106943744577, 1e-5),
             "MNEProjectToSurface: closest triangles, points and distances match an exhaustive search");

Authors of this file​