Use of Mapbox requires obtaining an API key and setting it locally,
functions that require this key provide information on doing this if a
valid key is not found.
Tiled imagery may be downloaded and cached by providing a spatial extent in
several possible formats, with optional control over provider, tile type,
format and zoom. Direct access to load a raster image will trigger the
tile download and caching, if required.
The release 0.6.0 of ceramic is available on CRAN: