openmap: Download map tiles
In mapmisc: Utilities for Producing Maps

openmap

R Documentation

Download map tiles

Description

Downloads map tiles from Openstreetmap.org and other servers.

Usage

	openmap(x, zoom, 
	  path="http://tile.openstreetmap.org/",
	  maxTiles = 9, 
	  crs=terra::crs(x),   
	  buffer=0, fact=1, 
	 verbose=getOption('mapmiscVerbose'),
	  cachePath=getOption('mapmiscCachePath'),
	  suffix=NULL
)

	osmTiles(name, xyz, suffix)

	openmapAttribution(name, 
	  type=c('text','latex','markdown','html', 'auto'), 
	  short=FALSE)

Arguments

`x`	An a spatial object from which an extent and crs can be obtained.
`zoom`	the zoom level, when missing it will be determined by maxTiles.
`path`	Source of map tiles, see http://diseasemapping.r-forge.r-project.org/mapLayers.html.
`maxTiles`	If zoom is missing, zoom will be chosen such that the number of map tiles is less than or equl to this number.
`crs`	Projection for the output, defaulting to the same projection as `x`. If `x` has no projection, for instance when `x` is a matrix or extent, `crs` is also used as the projection of `x`. If `crs` is `NA` or missing and `x` has no crs, long-lat is used.
`buffer`	Extend the extent for which the map is requested, in units of `x`. Can be negative, or a vector of length 2 for different x and y extensions
`fact`	Passed to increase or decrease resolution, values above 1 help to produce a clearer image.
`verbose`	Print information about map images being downloaded, defaults to `FALSE`.
`cachePath`	Location to store downloaded map images, defaults to `tempdir()`
`name`	name of a tile path, if missing a vector of all available tile paths is returned. `name` can be any of the names of the vector returned when `name` is unspecified.
`type`	format for the attribution
`short`	short or long attribution
`xyz`	format of xyz coordinates in URL's
`suffix`	string to append to URL's, i.e. `'.png'`

Details

These functions download, display, and manipulate map tiles stored in a standard way either on a web server or a local folder.

Map tiles are a set of PNG images that span the world at a set of zoom levels. Zoom level 1 has four 256x256 pixel tiles in a 2x2 pattern over the whole world. In general, zoom level n has 2^n by 2^n tiles. Zoom levels go up to about 17 or 18 depending on the tile server.

See http://diseasemapping.r-forge.r-project.org/mapLayers.html for a full set of map tiles.

Be sure to attribute any maps you publish, the osmAttribution function will assist. If type = 'auto' then markdown format will be used unless a variable mdToTex is defined and equal to TRUE.

Value

openmap returns a SpatRaster with indexed colours or RGB layers.

openmapAttribution returns a character string.

Examples


data("netherlands")
nldTiles = terra::unwrap(nldTiles)
plot(nldTiles)

openmapAttribution(nldTiles, short=TRUE, type='markdown')

openmapAttribution("stamen-toner", type='text')


myraster = rast(matrix(1:100,10,10),extent=ext(8, 18, 0, 10), crs=crsLL)

myPoints = as.points(myraster)[seq(1, ncell(myraster), len=12)]

names(osmTiles())


	mytiles = try(openmap(myraster, zoom=5, verbose=TRUE))

oldpar =	map.new(myraster)
	plot(mytiles, add=TRUE)
	points(myPoints,col='red')

	myPoints = project(myPoints, crsMerc)
	x = myPoints;path='waze'
	mytiles = try(openmap(myPoints,
		path='waze', verbose=TRUE, buffer=5))
	map.new(myPoints)
	plot(mytiles, add=TRUE)
	points(myPoints, col='red')
	openmapAttribution(mytiles)

par(oldpar)

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