mosaic

I = mosaic(lon, lat; pt_radius=6371007.0, provider="", zoom::Int=0, cache::String="",
           mapwidth=15, dpi=96, verbose::Int=0, kw...)

keywords: GMT, Julia, tiles image

Get image tiles from a web map tiles provider for given longitude, latitude coordinates.

Arguments

  • lon & lat:

    • lon, lat two scalars with the coordinates of region of interest center. To completly define the image area see the neighbors or mosaic option below.

    • lon, lat are two elements vector or matrix with the region's [lon_min, lon_max], [lat_min, lat_max].

    • Instead of two arguments, pass just one containing a GMTdataset obtained with the geocoder function. Example: mosaic(D, ...) or, if the search with geocoder was sufficiently generic (see its docs), mosaic(D, bbox=true) to use the BoundingBox returned by the query. bbox supports bb, BB or BoundingBox as aliases.

  • pt_radius: The planetary radius. Defaults to Earth's WGS84 authalic radius (6371007 m).

  • provider: Tile provider name. Currently available options are (but for more details see the docs of the getprovider function, i.e. ? getprovider):

    • "Bing" (the default), "OSM", "Esri" or a custom provider.

    • A Provider type from the TileProviders.jl package. You must consult the documentation of that package for more details on how to choose a provider.

  • zoom: Zoom level (0 for automatic). A number between 0 and ~19. The maximum is provider and area dependent. If zoom=0, the zoom level is computed automatically based on the mapwidth and dpi options.

  • cache: Full name of the the cache directory where to save the downloaded tiles. If empty, a cache directory is created in the system's TMP directory. If cache="gmt" the cache directory is created in ~/.gmt/cache_tileserver. NOTE: this normally is neeaded only for the first time you run this function when, if cache!="", the cache dir location is saved in the ~./gmt/tiles_cache_dir.txt file and used in subsequent calls.

  • mapwidth: Map width in cm. Used together with the dpi option to automatically compute the zoom level.

  • dpi: Dots per inch. Used together with the mapwidth option to automatically compute the zoom level.

  • verbose: Verbosity level. A number between 0 and 2. Print out info while downloading the image files. Silent when geting files from local cache unless verbose=2, where it prints out info about the files found in the cache.

kwargs (kw...)

  • neighbors or mosaic: When lon and lat are scalars, this option specifies the number of neighbors of the tile containing the query point to download. Normally this should be an odd number, but it can take the form of a matrix and the number of tiles is then determined by the number of rows and columns.

  • merc or mercator: Return tiled image in Mercator coordinates. The default is to project it back to geographical coordinates.

  • loose or loose_bounds: By default we return an image with the limits requested in the lon and lat arguments. This option makes it return an image with the limits that are determined by those of the tiles that intersect the requested region. Note that this does not work for point queries.

  • quadonly: Return only the quadtree string. A string or a matrix of strings when number of tiles > 1. Other from the quadtree string this option return also the decimal_adress, lon, lat, x, y that are: the XYZ tiles coordinates, the longitude, latitude , mercator X and Y coordinates in meters of first tile.

Returns

  • I: A GMTimage element or the output of the quadonly option explained above.

Examples

  • Make a figure with OpenStreetMap over Iberia maintaining the original spherical Mercator projection.

using GMT

I = mosaic([-9.5, 3.3], [36.0, 43.8], provider=:OSM, zoom=7, merc=true)
viz(I)

  • Make a figure of the Big Island of Hawaii using the default Bing images. In this case

we use the geocoder function to give us the map limits

using GMT

# Get the geographical limits of the Big Island in Hawaii
D = geocoder("Hawaii, Island");

# Get the image tiles of the Big Island in Hawaii using the Bing provider and automatic zoom level
I = mosaic(D, bbox=true);

viz(I)

See Also

geocoder