Stack many sources straight into an R array

ck_stack_read() is ck_stack() that hands back pixels instead of writing a file: it stacks the sources as separate bands (see ck_stack()) into an uncompressed /vsimem raster and reads it back as a base-R array.

Usage

ck_stack_read(
  src,
  t_srs = NULL,
  te = NULL,
  te_srs = NULL,
  tr = NULL,
  ts = NULL,
  tap = TRUE,
  r = c("near", "bilinear", "cubic", "cubicspline", "lanczos", "average", "rms", "mode",
    "max", "min", "med", "q1", "q3", "sum"),
  bands = NULL,
  cl_arg = character(0),
  num_threads = "ALL_CPUS",
  warp_memory = "auto",
  cache_max = "auto",
  config = NULL,
  skip_nosource = TRUE,
  overview = NULL,
  margin = 8L,
  io_concurrency = 16L,
  max_bytes = NULL,
  sanitise = TRUE
)

Arguments

src: Path/URL to a source GeoTIFF / COG, a cog_source() handle, or a character vector of several sources to mosaic (each tile's overlapping window is fetched and the set is reprojected/mosaicked in one warp; non-overlapping tiles are skipped). Passing a cog_source() reuses its already-open handle, skipping the metadata re-read – worthwhile when warping many AOIs from the same source.
t_srs: Target SRS (e.g. "EPSG:3857"). If NULL, the source CRS is used (no reprojection).
te: Target extent c(xmin, ymin, xmax, ymax), in te_srs if given, otherwise in t_srs. When supplied this is the AOI that drives the fetch.
te_srs: SRS of te (defaults to t_srs).
tr: Target resolution c(xres, yres) in target CRS units. Takes precedence over ts: if both are given, ts is ignored (with a warning).
ts: Target size c(width, height) in pixels. Ignored if tr is also supplied.
tap: If TRUE (default) and tr is given, align output pixel boundaries to the tr grid (gdalwarp -tap), anchored at the CRS origin, so outputs at the same resolution share a grid and stack cleanly. This snaps the output extent outward, so it is no longer exactly te. No effect with ts or on the copy path. An explicit -tap in cl_arg is always honoured. (warp_remote() never adds this; pass -tap yourself.)
r: Resampling method (used only on the warp path; a native-window copy ignores it). Either a single method applied to every source, or a vector of length length(src) giving a per-source method (e.g. "near" for a mask band, "bilinear" for reflectance).
bands: 1-based source bands to read (default: all). Subsetting happens during the fetch, so only those bands' bytes are streamed.
cl_arg: Character vector of extra raw gdalwarp flags, forwarded verbatim to gdalraster::warp() (e.g. c("-et", "0")). These are merged with the flags cptkirk builds from the named arguments above.
num_threads: Value for GDAL's warp NUM_THREADS warp option and the GDAL_NUM_THREADS config (default "ALL_CPUS"), parallelising the resampling computation and GeoTIFF (de)compression. NULL sets neither, deferring to the ambient GDAL_NUM_THREADS (env / session).
warp_memory: Warp working memory in MB (GDAL -wm). "auto" (default) uses ~25% of system RAM, clamped to 256-2048 MB (bigger means fewer, larger chunks); NULL defers to GDAL's own default; a number sets it explicitly.
cache_max: GDAL block cache in MB for this call. "auto" (default) uses ~25% of RAM, clamped to 256-2000 MB; NULL defers to the ambient GDAL_CACHEMAX (env / gdalraster::set_config_option()); a number sets it explicitly. Any value is restored to the previous setting afterwards.
config: Named character vector / list of extra GDAL config options to set for the duration of the call (restored on exit).
skip_nosource: If TRUE (default), pass SKIP_NOSOURCE=YES + INIT_DEST so the warper skips output chunks with no source coverage (e.g. nodata margins from reprojection). No effect when output is fully covered. Ignored on the copy fast-path.
overview: Force a 1-based IFD/overview level instead of auto-selecting from the output resolution. 1 = full resolution.
margin: Source-pixel margin added around the computed window to cover the resampling kernel and reprojection slop (default 8).
io_concurrency: Number of concurrent tile reads – the width of the single global fetch pool shared across all source tiles. Default 16, which suits object stores that throttle around that many simultaneous range requests (e.g. S3 / source.coop). Raise (24-32) on a fast, stable link; lower if a store rate-limits.
max_bytes: Safety ceiling (bytes) on the returned array, sized as nrow * ncol * nbands * 8. NULL (default) uses ~1/3 of system RAM.
sanitise: If TRUE (default), validate the warp arguments against a tiny metadata-derived stand-in before fetching, so a bad CRS, resampling method, creation option or unknown flag fails in milliseconds instead of after a remote read. Set FALSE to skip the check.

Value

A numeric array with dimensions [nrow, ncol, nband] (or a matrix for a single output band), carrying geotransform, crs and (when set) nodata attributes. Band names are not preserved on the array.

Usage

Arguments

Value

See also