Add an RGB image as a layer

Create a Red-Green-Blue image overlay from a RasterStack / RasterBrick or stars object based on three layers. Three layers (sometimes referred to as "bands" because they may represent different bandwidths in the electromagnetic spectrum) are combined such that they represent the red, green and blue channel. This function can be used to make 'true (or false) color images' from Landsat and other multi-band satellite images. Note, this text is plagiarized, i.e. copied from plotRGB. addRasterRGB and addStarsRGB are aliases.

Usage

addRasterRGB(
  map,
  x,
  r = 3,
  g = 2,
  b = 1,
  quantiles = c(0, 1),
  domain = NULL,
  na.color = "#BEBEBE80",
  method = c("auto", "bilinear", "near", "average", "mode", "cubic", "cubicspline",
    "lanczos", "sum", "min", "q1", "median", "q3", "max", "rms"),
  ...
)

addStarsRGB(
  map,
  x,
  r = 3,
  g = 2,
  b = 1,
  quantiles = c(0, 1),
  domain = NULL,
  na.color = "#BEBEBE80",
  method = c("auto", "bilinear", "near", "average", "mode", "cubic", "cubicspline",
    "lanczos", "sum", "min", "q1", "median", "q3", "max", "rms"),
  ...
)

Arguments

map

a map widget object created from `leaflet()“

x

a RasterBrick, RasterStack or `stars“ raster object

r

integer. Index of the Red channel/band, between 1 and nlayers(x)

g

integer. Index of the Green channel/band, between 1 and nlayers(x)

b

integer. Index of the Blue channel/band, between 1 and nlayers(x)

quantiles

the upper and lower quantiles used for color stretching. If set to NULL, stretching is performed basing on domain argument.

domain

the upper and lower values used for color stretching. This is used only if quantiles is NULL. If both domain and quantiles are set to NULL, stretching is applied based on min-max values.

na.color

the color to be used for NA pixels

method

character. Method used for estimating the new cell values of a SpatRaster. One of:

bilinear: bilinear interpolation (3x3 cell window). This is used by default if the first layer of x is not categorical

average: This can be a good choice with continuous variables if the output cells overlap with multiple input cells.

near: nearest neighbor. This is used by default if the first layer of x is categorical. This method is not a good choice for continuous values.

mode: The modal value. This can be a good choice for categrical rasters, if the output cells overlap with multiple input cells.

cubic: cubic interpolation (5x5 cell window).

cubicspline: cubic B-spline interpolation. (5x5 cell window).

lanczos: Lanczos windowed sinc resampling. (7x7 cell window).

sum: the weighted sum of all non-NA contributing grid cells.

min, q1, median, q3, max: the minimum, first quartile, median, third quartile, or maximum value.

rms: the root-mean-square value of all non-NA contributing grid cells.

...

additional arguments passed on to addRasterImage

Details

Note, method auto, the default, will choose between near for factorial and bilinear for numeric data. All other methods need to be set manually.

Author

Tim Appelhans, Luigi Ranghetti

Examples

# \donttest{
  require(raster)
  require(stars)
#> Loading required package: stars
#> Loading required package: abind
#> Loading required package: sf
#> Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.4.0; sf_use_s2() is TRUE
  require(plainview)
#> Loading required package: plainview
  require(leaflet)

  leaflet() %>%
    addTiles(group = "OpenStreetMap") %>%
    addRasterRGB(plainview::poppendorf, 4,3,2, group = "True colours") %>%
    addStarsRGB(st_as_stars(plainview::poppendorf), 5,4,3, group = "False colours") %>%
    addLayersControl(
      baseGroups = c("Satellite"),
      overlayGroups = c("True colours", "False colours"),
    )

# }