getPointsOutAlphaHull: Generate Spatial object from Alpha Hull object

Description

Generate polygon based on alpha hulls at a given alpha parmater

Usage

getPointsOutAlphaHull(
  x,
  alpha = 2,
  coordHeaders = c("Longitude", "Latitude"),
  proj = "+proj=longlat +datum=WGS84",
  verbose = FALSE,
  alphaCap = 20
)

Value

a list with 2 elements:

hull: a SpatialPolygons object
alpha: the alpha value that was found to satisfy the criteria. If a convex hull was returned, this will list MCH.

Arguments

x: dataframe of coordinates in decimal degrees, with a minimum of 3 rows.
alpha: the starting value for alpha.
coordHeaders: the column names for the longitude and latitude columns, respectively. If x has two columns, these are assumed to be longitude and latitude, and coordHeaders is ignored.
proj: the projection information for x. The default is currently the only supported option.
verbose: logical. print messages? Default to FALSE
alphaCap: Max alpha value before function aborts and returns a minimum convex hull.

Author

Pascal Title (original version), Josep M Serra-Diaz (modifs)

Details

Based on rangeBuilder::getDynamicRange without cropping to sea and without increments alpha = initialAlpha, and will then increase alpha by alphaIncrement until both the fraction and partCount conditions are met.

If the conditions cannot be satisfied, then a minimum convex hull is returned.