tile_spec: Create tile specification

In hypertidy/grout: Create Raster Tiles

Create tile specification

Description

Take an input grid (dimension and extent) and create a specification of the tiling for that grid within a profile.

Usage

tile_spec(
  dimension,
  extent,
  zoom = 0,
  blocksize = c(256L, 256L),
  profile = c("mercator", "geodetic", "raster"),
  crs = NA,
  xyz = FALSE
)

tile_zoom(
  dimension,
  extent,
  blocksize = c(256L, 256L),
  profile = c("mercator", "geodetic", "raster")
)

Arguments

dimension	size in pixels ncol,nrow
extent	xmin,xmax,ymin,ymax
zoom	the zoom level, starts at 0 and can be up to 24
blocksize	size of each tile, defaults to 256x256
profile	profile domain to use, see Details
crs	crs, for raster profile
xyz	default is 'FALSE', if 'TRUE' use xyz-mode (zero is at the top)

Details

Profiles are 'mercator' or "geodetic" for global systems, or can use "raster" which will use the input grid specification as the entire domain.

'tile_row' in output is in TMS orientation (zero is at the bottom), use 'xyz' arg to switch.

Function 'tile_zoom()' will return the "natural" maximum zoom level, i.e. the zoom at which the tile resolution is just below the input resolution. Note that no reprojection is done, the input extent must match the profile chosen (use 'raster' for native profile).

Value

data frame with tile specification, tile index, tile_col, tile_row, ncol, nrow, xmin, xmax, ymin, ymax, crs

Examples

tile_spec(c(8194, 8194), c(140, 155, -45, -30), profile = "geodetic")

tile_spec(c(2048, 248), c(140, 155, -45, -30), zoom = 5, profile = "geodetic", 
   blocksize = c(512, 512))

hypertidy/grout documentation built on July 19, 2024, 8:33 p.m.