staticmap_getEsrimapBrick: Create a rasterBrick from an Esri tiled image server

In PWFSLSmoke: Utilities for Working with Air Quality Monitoring Data

Description

Uses the input coordinates to fetch and composite a raster from the tile server. Returns a raster::rasterBrick object. This can then passed as the rasterBrick object to the staticmap_plotRasterBrick() function for plotting.

As of July 2019, this list is a handy reference to the freely available tile servers which can be previewed at the following URL:

https://leaflet-extras.github.io/leaflet-providers/preview/

Usage

staticmap_getEsrimapBrick(
  centerLon = NULL,
  centerLat = NULL,
  maptype = "world_topo",
  zoom = 12,
  width = 640,
  height = 640,
  bbox = NULL,
  maxTiles = 20,
  crs = sp::CRS("+init=epsg:4326"),
  tileCacheDir = tempdir()
)

Arguments

centerLon	Map center longitude.
centerLat	Map center latitude.
maptype	Selects the appropriate Esri tile server. Options include: "world_topo" "world_imagery" "world_terrain" "de_Lorme" "world_grey" "world_streets"
zoom	map Zoom level.
width	Width of image, in pixels.
height	Height of image, in pixels.
bbox	Bounding box vector (lonLo, latLo, lonHi, latHi). If not null, centerLon, centerLat, and zoom are ignored.
maxTiles	Maximum number of tiles to be returned. The greater the number, the slower the performance – arbitrarily set to 20 by default.
crs	Object of class CRS. The Coordinate Reference System (CRS) for the returned map. If the CRS of the downloaded map does not match, it will be projected to the specified CRS using raster::projectRaster.
tileCacheDir	Optional location for cached tiles.

Value

A rasterBrick object which can be plotted with staticmap_plotRasterBrick() or raster::plotRGB() and serve as a base plot.

Note

The spatial reference of the image when it is downloaded is 3857. If the crs argument is different, projecting may cause the size and extent of the image to differ very slightly from the input, on a scale of 1-2 pixels or 10^-3 degrees.

If bbox is specified and the bbox aspect ratio does not match the width/height aspect ratio the extent is resized to prevent the map image from appearing stretched, so the map extent may not match the bbox argument exactly.

If both zoom and maxTiles are specified, maxTiles takes precedence. To get a specified zoom level, set maxTiles = NULL.

See Also

staticmap_getRasterBrick

staticmap_plotRasterBrick

Examples

## Not run: 
# Fail gracefully if any resources are not available
try({

rasterBrick <- staticmap_getEsrimapBrick(-122.3318, 47.668)
staticmap_plotRasterBrick(rasterBrick)

}, silent = FALSE)

## End(Not run)

PWFSLSmoke documentation built on Nov. 23, 2021, 5:06 p.m.