contrastFilterSegmentation: Contrast-Filter-Segmentation

In raff-k/Lslide: Functions for object-oriented image analysis in landslide science

Contrast-Filter-Segmentation

Description

This function performs a contrast filter segmentation on an input RasterLayer. In the firest stept the raster is converted to a gray-scale matrix, followed by filter functions of the EBImage package. Then, the filtering is applied as mask on the segmentation-input. Afterwards, a segmentation is performed using GRASS GIS region growing. Finally, the segments are transformed to SpatialPolygonsDataFrame and returned as function output. In the future this funcion will be included in the segmentation-function.

Usage

contrastFilterSegmentation(input.filter,
  input.segmentation = input.filter, offset = 0.06,
  makeBrush.size = 25, makeBrush.shape = "disc", NA.val.in = 0,
  clump.thresh = NULL, clump.directions = 4,
  env.rsaga = RSAGA::rsaga.env(), CFR.buf = 1,
  output.path = tempdir(), writeCFRaster = FALSE,
  writeRaster.NAflag = -99999, freeMemory = TRUE,
  show.output.on.console = FALSE, quiet = TRUE, morph.Closing = TRUE,
  closing.size = 3, closing.shape = "box",
  Grass.Segmentation.Threshold = 0.24, Grass.Segmentation.Minsize = 1,
  Grass.Segmentation.Memory = 1024,
  Segments.Poly = file.path(tempdir(), "outSegPoly.shp"),
  Segments.Grid = file.path(tempdir(), "outSegGrid.sgrd"),
  defaultGrass = c("C:/OSGeo4W64", "grass-7.2.2", "OSGeo4W64"),
  load.output = FALSE, fill.holes = FALSE, ...)

Arguments

input.filter	RasterLayer on which the filtering is applied
input.segmentation	RasterLayer for segmentation. Default: input.filter
offset	Offset of values in filter matrix. Default: 0.06
makeBrush.size	matrix size for smoothing input.filter. Default: 25
makeBrush.shape	form of smoothin matrix. Default: "disc"
NA.val.in	replace value for no data (NA) in input.filter. Default: 0
clump.thresh	area thresholds for removing clumbs - measured in cell sizes. Default: NULL
clump.directions	directions for "clump-searching". Default: 8
env.rsaga	environment of SAGA GIS. Default: RSAGA::rsaga.env()
CFR.buf	buffer applied on contrast-filter-results, measured in cell-sizes. Default: "1"
output.path	path for output files. Default: tempdir()
writeCFRaster	write contrast-filter results. Default: FALSE
writeRaster.NAflag	NoData values for NA values in raster. Default: -99999
freeMemory	free memory after contrast filtering. Default: TRUE
show.output.on.console	show output of tools on console. Default: FALSE
quiet	do not show comments and process time in console. Default: TRUE
Grass.Segmentation.Threshold	threshold used of merging segments. Default: 0.24
Grass.Segmentation.Minsize	minsize of a segment. Default: 0
Grass.Segmentation.Memory	memory used in computation. Default: 1024
Segments.Poly	output location for segmented objects (shapefile). Default: paste0(tempdir(), "/", "outSegPoly.shp")
Segments.Grid	output location for segmented grid. Default: paste0(tempdir(), "/", "outSegGrid.sgrd")
defaultGrass	GRASS GIS environmet for temporal setup, see package link2GI. Default: c("C:/OSGeo4W64", "grass-7.2.2", "OSGeo4W64")
fill.holes	polygon segmentation output contains holes. Default: FALSE
Fast.Representativeness.LevelOfGeneralisation	level of generalisation for computing seed points. Default: "2.0"

Value

SpatialPolygonsDataFrame containing the segments/objects

Note

• r is stretched to gray-scale (0-255) during process by linear normalization

raff-k/Lslide documentation built on March 29, 2022, 6:52 p.m.