rDistance: Calculate the distance map for a raster
In EhrmannS/rasterTools: Obtain and process earth observation data

Description Usage Arguments Details Value References See Also Examples

The distance map of a binarised raster contains the distance of each background cell to the nearest foreground cell.

1	rDistance(obj, method = "euclidean")

`obj`	[`RasterLayer(1)`] The object to modify.
`method`	[`character(1)`] the distance measure to be calculated. Either `"euclidean"` (default), `"manhatten"` or `"chessboard"` distance.

In contrast to distance, the distance values here do not warp around the boundaries of the map.

A RasterLayer of the same dimension as obj, where the value of the background cells has been replaced with the distance to the nearest foreground cell.

Meijster, A., Roerdink, J.B.T.M., Hesselink, W.H., 2000. A general algorithm for computing distance transforms in linear time, in: Goutsias, J., Vincent, L., Bloomberg, D.S. (Eds.), Mathematical Morphology and Its Applications to Image and Signal Processing. Springer, pp. 331–340.

Other operators to modify cell values: rBinarise, rCategorise, rFillNA, rOffset, rPermute, rRange, rSubstitute

input <- rtRasters$continuous

# the different distance metrics
binarised <- rBinarise(input, thresh = 40)
disEuc <- rDistance(binarised)
disMan <- rDistance(binarised, method = "manhattan")
disChb <- rDistance(binarised, method = "chessboard")

distances <- raster::stack(binarised, disEuc, disMan, disChb)
visualise(distances)

# calculate distance from edge to patch interior
inverted <- rPermute(binarised)
visualise(rDistance(inverted))