R: Convert Window to Binary Mask under Constraints

owin2mask {spatstat.geom} | R Documentation

## Convert Window to Binary Mask under Constraints

### Description

Converts a window (object of class `"owin"`) to a binary pixel mask, with options to require that the inside, outside, and/or boundary of the window should be completely covered.

### Usage

    owin2mask(W,
             op = c("sample", "notsample",
                    "cover", "inside",
                    "uncover", "outside", "boundary"),
             ...)

### Arguments

`W` | A window (object of class `"owin"`).
`op` | Character string (partially matched) specifying how `W` should be converted to a binary pixel mask.
`...` | Optional arguments passed to `as.mask` to determine the pixel resolution.

### Details

This function is similar to, but more flexible than, `as.mask`. It converts the interior, exterior, or boundary of the window `W` to a binary pixel mask.

- If `op="sample"` (the default), the mask consists of all pixels whose centres lie inside the window `W`. This is the same as using `as.mask`.

- If `op="notsample"`, the mask consists of all pixels whose centres lie outside the window `W`. This is the same as using `as.mask` followed by `complement.owin`.

- If `op="cover"`, the mask consists of all pixels which overlap the window `W`, wholly or partially.

- If `op="inside"`, the mask consists of all pixels which lie entirely inside the window `W`.

- If `op="uncover"`, the mask consists of all pixels which overlap the outside of the window `W`, wholly or partially.

- If `op="outside"`, the mask consists of all pixels which lie entirely outside the window `W`.

- If `op="boundary"`, the mask consists of all pixels which overlap the boundary of the window `W`.

### Value

A mask (object of class `"owin"` of type `"mask"` representing a binary pixel mask).

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au.

### See Also

`as.mask`

### Examples

      W <- Window(chorley)
      opa <- par(mfrow=c(2,4))
      plot(as.mask(W, dimyx=16), col="grey", main="as.mask")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(owin2mask(W, "i", dimyx=16), col="grey", main="inside")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(owin2mask(W, "c", dimyx=16), col="grey", main="cover")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(owin2mask(W, "b", dimyx=16), col="grey", main="boundary")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(as.mask(complement.owin(W), dimyx=16), col="grey",
           main="as.mask(complement.owin)")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(owin2mask(W, "o", dimyx=16), col="grey", main="outside")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(owin2mask(W, "u", dimyx=16), col="grey", main="uncover")
      plot(W, add=TRUE, lwd=3, border="red")
      plot(owin2mask(W, "b", dimyx=16), col="grey", main="boundary")
      plot(W, add=TRUE, lwd=3, border="red")
      par(opa)

[Package spatstat.geom version 2.3-2 Index]