concaveman: A very fast 2D concave hull algorithm.
This package is a simple R port (through V8) of a JavaScript library by Vladimir Agafonkin.
The concaveman function ports the concaveman library from mapbox. It computes the concave polygon for one set of points.
concaveman(points, concavity, length_threshold) ## S3 method for class 'matrix' concaveman(points, concavity = 2, length_threshold = 0) ## S3 method for class 'sf' concaveman(points, concavity = 2, length_threshold = 0)
points |
the points for which the concave hull must be computed. Can be represented as a matrix of coordinates or an |
concavity |
a relative measure of concavity. 1 results in a relatively detailed shape, Infinity results in a convex hull. You can use values lower than 1, but they can produce pretty crazy shapes. |
length_threshold |
when a segment length is under this threshold, it stops being considered for further detalization. Higher values result in simpler shapes. |
For details regarding the implementation, please see the original javascript library github page. This is just a thin wrapper, via V8.
an object of the same class as points: a matrix of coordinates or an sf object.
data(points) polygons <- concaveman(points) plot(points) plot(polygons, add = TRUE)
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.