Struct VolumeMotion 

pub struct VolumeMotion {
    pub index: usize,
    pub transform: RigidTransform,
    pub bdir: (f64, f64, f64),
    pub rotation_deg: f64,
    pub translation_mm: f64,
    pub max_displacement_mm: f64,
    pub ncc: f64,
    pub overlap: f64,
    pub suspect: bool,
}

Where one volume of a series was, and which way B0 pointed while it was there.

Fields

index: usize

Index into the input series.

transform: RigidTransform

The recovered alignment onto the reference volume. Identity for the reference itself.

bdir: (f64, f64, f64)

This volume’s B0 direction in the reference grid’s voxel frame — the direction its field map was acquired under, and the one a dipole kernel built on the reference grid has to use for it.

For the reference volume this is just its own direction. For a volume whose head had rotated it is that direction carried through the recovered rotation, which is the whole point: the object rotated and B0 did not.

rotation_deg: f64

Total rotation angle in degrees, regardless of axis.

translation_mm: f64

Translation magnitude in mm of world space.

max_displacement_mm: f64

Largest distance any tissue inside the evaluation domain actually moved, in mm.

Rotation and translation are not comparable to each other or to a voxel size, and a small rotation about a distant centre moves tissue a long way. This is the single number that answers “did this matter”: compare it against the voxel size. The domain is the mask when one was passed to estimate_motion and the reference grid’s corners otherwise; the maximum of a rigid displacement field over a convex region is attained at an extreme point, so the corner case is exact for the box rather than a sample of it.

ncc: f64

Normalised cross-correlation at the solution. 1.0 for the reference volume.

overlap: f64

Fraction of sampled reference voxels that found a sample in this volume. 1.0 for the reference volume.

suspect: bool

The estimate is not to be trusted: NCC below MotionParams::min_ncc, or overlap below RigidParams::min_overlap.

Not a motion flag — a volume can move a long way and be registered perfectly, and that is the normal case. This says the registration itself may have failed, so transform, bdir and everything derived from them are questionable. Deciding what to do about a volume whose data is corrupted — dropping it, downweighting it in an echo combination — is a separate problem that belongs with [crate::utils::multi_echo]’s weighting, and this module deliberately does not do it.

Trait Implementations

impl Clone for VolumeMotion

fn clone(&self) -> VolumeMotion

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for VolumeMotion

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.