``Homotopic_Thinning'' - thin an input volume

VFX name:

iHomotopicThin

IMPROMPTU Equivalent:

Homotopic_Thinning

purpose:

Thin an input binary-valued volume. ``Thin'' means to delete the outer layer of objects without changing the connectivity (homotopy) of the objects [24,25]. By thinning to completion, you can get the skeletons of objects in the volume.

The operation can be done in 3-D or 2-D. Also, when thinning to completion, short branches of the skeleton - such as branches corresponding to small and possibly noisy geometrical components of an object - can be suppressed.

The 3-D method is based on [18,29]. The 2-D method is a simple template-checking technique.

input:

An 8-bit binary-valued volume.

output:

An 8-bit binary-valued volume.

parameters:

Default parameters menu is

dimensions = 3-D
num_passes = to completion
min_branch_length = 5
connectivity = 8/26

The ``dimensions'' toggles between ``3-D'' and ``2-D'' - it determines how the thinning is done.

The ``num_passes'' can be used to specify the number of iterations of thinning. Leaving the parameter at ``num_passes = to completion'' will thin the volume down to a skeleton.

The ``min_branch_length'' parameter specifies the shortest skeletal branches preserved (in voxels).

comments:

1.

This can be a slow operation depending on the geometrical complexity of objects in the volume. Thinning a 100x100x100 arterial-tree volume, for example, could require perhaps 20 iterations of thinning and take 10 to 15 minutes.