tfmri.sampling.estimate_radial_density

estimate_radial_density(points, readout_os=2.0)[source]

Estimate the sampling density of a radial k-space trajectory.

This function estimates the density based on the radius of each sample, but does not take into account the relationships between different spokes or views. This function should work well as long as the spacing between radial spokes is reasonably uniform. If this is not the case, consider also tfmri.sampling.radial_density or tfmri.sampling.estimate_density.

This function supports 2D and 3D (“koosh-ball”) radial trajectories.

Warning

This function assumes that points represents a radial trajectory, but cannot verify that. If used with trajectories other than radial, it will not fail but the result will be invalid.

Parameters

  • points – A Tensor. Must be one of the following types: float32, float64. The coordinates at which the sampling density should be estimated. Must have shape [..., views, samples, rank]. The coordinates should be in radians/pixel, ie, in the range [-pi, pi]. Must represent a radial trajectory.

  • readout_os – A float. The readout oversampling factor. Defaults to 2.0.

Returns

A Tensor of shape [...] containing the density of points.

Raises

ValueError – If any of the passed inputs is invalid.