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spatstat.geom (version 3.6-0)

discs: Union of Discs

Description

Make a spatial region composed of discs with given centres and radii.

Usage

discs(centres, radii = marks(centres)/2, ...,
        separate = FALSE, mask = FALSE, trim = TRUE,
        delta = NULL, npoly=NULL)

Arguments

Value

If separate=FALSE, a window (object of class "owin").

If separate=TRUE, a list of windows.

Details

This command is typically applied to a marked point pattern dataset X in which the marks represent the sizes of objects. The result is a spatial region representing the space occupied by the objects.

If the marks of X represent the diameters of circular objects, then the result of discs(X) is a spatial region constructed by taking discs, of the specified diameters, centred at the points of X, and forming the union of these discs. If the marks of X represent the areas of objects, one could take discs(X, sqrt(marks(X)/pi)) to produce discs of equivalent area.

A fast algorithm is used to compute the result as a binary mask, when mask=TRUE. This option is recommended unless polygons are really necessary.

If mask=FALSE, the discs will be constructed as polygons by the function disc. To avoid computational problems, by default, the discs will all be constructed using the same physical tolerance value delta passed to disc. The default is such that the smallest disc will be approximated by a 16-sided polygon. (The argument npoly should not normally be used, to avoid computational problems arising with small radii.)

See Also

disc, union.owin

Examples

Run this code
  plot(discs(anemones, mask=TRUE, eps=0.5))

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