orientation, data, widths [, orientation,
values, wavenumbers, grid, aspect, order,
Determines local orientation in 2D or 3D data employing a method based on local Fourier Transforms.
The 2D or 3D array in which orientations are to be determined.
must be a 2 or 3-element vector containing the FWHM of the Gaussian smoothing kernels applied in the dimensions (0 means no smoothing).
is a 2 or 3-element vector containing the desired dimensions of the
results. If it is not specified, then the results will have the same
specifies the dimensions of a pixel, if they do not have an aspect ratio of 1.
contains the approximation order of the calculations, a number between 1 and 4 (default, most accurate).
The found orientation is returned in this argument (if specified),
/getj is specified. The orientation is expressed in the
2d case as an angle in radians measured counterclockwise from the
positive x-axis, and in the 3D case as a 2-element vector containing the
x and y coordinates of the orientation vector relative to a unit z
The found eigenvalues (measures for the data gradients in the principal
directions) are returned in this argument (if specified), unless
/getj is specified. The eigenvalues are returned in descending
By default, the determined local wavenumber in the direction of the
found orientation is returned in this argument (if specified), unless
/getj is specified. If
/perpendicular is specified, then
– for two-dimensional data only – the local wavenumber in the
direction perpendicular to the found orientation is returned instead.
The wavenumber is measured in units of one data element. A data set
with values equal to sin(x) returns a wavenumber of 1 for the
perpendicular wavenumber, and 0 for the parallel wavenumber.
If a random data set is smoothed over FWHM
w in one direction,
then the parallel local wavenumber is on average equal to about
If specified, then the unique elements of the inertia tensor are
values (the diagonal elements) and
orientation (the off-diagonal elements), and the local
wavenumber. This keyword is supplied for
debugging purposes and may be withdrawn in the future.
Induces periodical display of the progress status.
The returned orientations are ambiguous over 180 degrees.
|• orientation details:|