Skeletonisation is the process of thinning a shape to a medial line or surface, and can be achieved using elementary mathematical morphology operations in a number of ways. Three methods are available through this function. They are all iterative and therefore relatively time-consuming.
skeletonise(x, kernel = NULL, method = c("lantuejoul", "beucher",
"hitormiss"))A skeletonised array with the same dimensions as the original array.
An object that can be coerced to an array, or for which a
morph method exists.
An array representing the kernel to be used for the underlying
morphology operations. The kernel is fixed for the "hitormiss"
method, so this argument will be ignored.
A string giving the method to use. See Details.
Jon Clayden <code@clayden.org>
The default method is Lantuéjoul's formula, a union across repeated
erosions, which works in any number of dimensions and may produce
reasonable results on greyscale images, but does not in general produce a
connected skeleton. Beucher introduced an alternative which may produce a
better result (although again the skeleton may not be connected), but this
implementation of the latter algorithm only applies to binary arrays. The
final method uses the so-called hit-or-miss transform, which searches for
exact patterns in the source array. This is guaranteed to produce a
connected skeleton, which is often desirable, but uses fixed kernels (so the
kernel argument is ignored) and is currently only implemented for 2D
binary arrays.
C. Lantuéjoul (1977). Sur le modèle de Johnson-Mehl généralisé. Technical report, Centre de Morphologie Mathématique, Fontainebleau, France.
S. Beucher (1994). Digital skeletons in Euclidean and geodesic spaces. Signal Processing 38(1):127-141. tools:::Rd_expr_doi("10.1016/0165-1684(94)90061-2").
morphology
x <- c(0,0,1,0,0,0,1,1,1,0,0)
k <- c(1,1,1)
skeletonise(x,k)
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