movingwindow {landsat}

Simple moving window function.

Description

Very simple function to apply a kernel to a matrix across a moving window.

Usage

movingwindow(x, kernel, na.rm=TRUE)

Arguments

x

A matrix.

kernel

The kernel to be applied to the matrix, for example a Sobel kernel.

na.rm

NA handling option to be passed to sum(). If TRUE, NA will be returned if any value under the kernel is NA or NaN, otherwise NA values will be omitted.

Details

This function is used in the calculation of slope and aspect by slopeasp().

Value

Returns the transformed matrix.

Note

Should be rewritten in C for greater efficiency.

Author(s)

Sarah Goslee

See Also

slopeasp

Examples

	data(dem)
	dem.smoothed <- movingwindow(dem, matrix(c(1,1,1,1,0,1,1,1,1), 3, 3)/8)

	par(mfrow=c(1,2))
	image(dem)
	image(dem.smoothed)