tonerToTrans: Convert RGB maps to semi-transparent

View source: R/tonerToTrans.R

tonerToTransR Documentation

Convert RGB maps to semi-transparent

Description

Stamen-toner maps are 3-layer RGB rasters, which are converted to single-layer rasters with indexed colours with whites becoming transparent.

Usage

tonerToTrans(x,  pattern="(red|green|blue)$", power = 0.5, col='black',  threshold=Inf)

Arguments

x

A RasterStack with RGB colours, such as from openmap with path='stamen-toner'

pattern

string passed to grep to find RGB layers.

power

Values below 1 increase opacity, above 1 increases transparency

col

colour for resulting map

threshold

colours above this value are transparent

Details

Intended for 'stamen-toner' maps.

Value

A SpatRast with indexed colours

Author(s)

Patrick Brown

See Also

openmap

Examples


	data('worldMap');worldMap = unwrap(worldMap)

	origMap = openmap(worldMap[worldMap$NAME == 'Sierra Leone',],
	 path='stamen-toner',  
		buffer=100*1000
	)
		# path = 'https://tiles.stadiamaps.com/tiles/stamen_toner/')
	#	suffix = '@2x.png')
	oldpar=	map.new(origMap, bg='green')
	plot(origMap, add=TRUE)
	
	transMap = tonerToTrans(origMap)
	names(transMap)
  map.new(transMap, bg='green')
	plot(transMap, add=TRUE)
	par(oldpar)



mapmisc documentation built on Nov. 21, 2023, 5:09 p.m.