mapview (version 1.1.0)

viewRGB: Red-Green-Blue map view of a multi-layered Raster object

Description

Make a Red-Green-Blue plot based on three layers (in a RasterBrick or RasterStack). 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 plagirized, i.e. copied from plotRGB.

Usage

"viewRGB"(x, r = 3, g = 2, b = 1, quantiles = c(0.02, 0.98), map = NULL, maxpixels = mapviewGetOption("mapview.maxpixels"), map.types = mapviewGetOption("basemaps"), na.color = mapviewGetOption("na.color"), layer.name = deparse(substitute(x, env = parent.frame())), ...)

Arguments

x

a RasterBrick or RasterStack

r

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

g

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

b

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

quantiles

the upper and lower quantiles used for color stretching

map

the map to which the layer should be added

maxpixels

integer > 0. Maximum number of cells to use for the plot. If maxpixels < ncell(x), sampleRegular is used before plotting.

map.types

character spcifications for the base maps. see http://leaflet-extras.github.io/leaflet-providers/preview/ for available options.

na.color

the color to be used for NA pixels

layer.name

the name of the layer to be shown on the map

...

additional arguments passed on to mapView

Examples

### raster data ###
library(sp)
library(raster)

data(poppendorf)

viewRGB(poppendorf, 4, 3, 2) # true-color
viewRGB(poppendorf, 5, 4, 3) # false-color

## Not run: 
# ### can also be used to view any type of image (here an example of the
# ### package author teaching R on the research station at Kilimanjaro)
# ### solution on how to read images from the web found here
# ### http://r.789695.n4.nabble.com/readJPEG-function-cannot-open-jpeg-files-td4655487.html
# library(jpeg)
# library(raster)
# 
# web_img <- "http://umweltinformatik-marburg.de/uploads/tx_rzslider/teaching_header_kili_resized.jpg"
# 
# jpg <- readJPEG(readBin(web_img, "raw", 1e6))
# 
# # Convert imagedata to raster
# rst_blue <- raster(jpg[, , 1])
# rst_green <- raster(jpg[, , 2])
# rst_red <- raster(jpg[, , 3])
# 
# img <- brick(rst_red, rst_green, rst_blue)
# 
# viewRGB(img)
# ## End(Not run)