rMorph: Morphologically modify a raster

Description Usage Arguments Details References See Also

Description

Morphologically modify a raster

Usage

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rMorph(obj, kernel = NULL, blend = NULL, merge = NULL,
  rotate = TRUE, strictKernel = TRUE, background = NULL)

Arguments

obj

[RasterLayer(1)]
The object to modify.

kernel

[matrix(.) | list(.) thereof]
scan the raster with this kernel (default is a 3 by 3 cells diamond kernel).

blend

[character(1)]
identity, equal, lower, greater, plus, minus, product; see Details.

merge

[character(1)]
min, max, all, any, sum, mean, median, sd, cv, one, zero, na; see Details.

rotate

[logical(1)]
should the kernel be applied for all possible rotations (TRUE, default) or should the kernel be used as is (FALSE)?

strictKernel

[logical(1)]

background

[integerish(1)]
the value any cell with value NA should have.

Details

The morphC function (internal) is the basis of many modify operations in rasterTools and rMorph exposes a fully functional interface of this C++ function. The morphC function iteratively goes through each pixel of a raster (obj) and compares the kernel with the raster at that location. The result of this comparison depends on the arguments blend and merge:

The following functions are defined for blend:

  1. identity: the value of obj where kernel is not NA.

  2. equal: the value 1 where obj and kernel are equal, otherwise the value 0.

  3. lower: the values of obj that are lower than kernel, otherwise 0.

  4. greater: the values of obj that are greater than kernel, otherwise 0.

  5. plus: the values of obj added to the values of kernel.

  6. minus: the values of kernel subtracted from the values of obj.

  7. product: the product of the values of obj and kernel.

The following functions are defined for merge:

  1. min: the minimum value.

  2. max: the maximum value.

  3. all: the value 1 if all non-NA values are not 0, otherwise 0.

  4. any: the value 1 if any of the non-NA values are not 0, otherwise 0.

  5. sum: the sum of all non-NA values.

  6. mean: the mean of all non-NA values.

  7. median: the median of all non-NA values.

  8. sd: the standard deviation of all non-NA values.

  9. cv: the coefficient of variation of all non-NA values.

  10. sumNa: if the sum of all values is greater than 0 than this sum, otherwise NA.

References

Credit for the original idea/architecture of the C++ part of this function goes to Jon Clayden (R::mmand). The functionality has been slightly extended here.

See Also

Other operators to morphologically modify a raster: rDilate, rErode


EhrmannS/rasterTools documentation built on May 28, 2019, 8:24 a.m.