process_modis_warp: Warp MODIS swath data into rectilinear grid raster

In amadeus: Accessing and Analyzing Large-Scale Environmental Data

Warp MODIS swath data into rectilinear grid raster

Description

Swath data is a type of MODIS data, where curvilinear points are stored with varying resolution depending on the relative position of the sensor axis. As this type of data typically does not work well with planar spatial data, users should warp or rectify this data into a rectilinear raster. Main procedure is done with stars::st_warp, in which users are able to customize the threshold to fill potential gaps that appear where the target resolution is finer than the local resolution of curvilinear grid points.

Usage

process_modis_warp(
  path = NULL,
  cellsize = 0.1,
  threshold = cellsize * 4,
  crs = 4326,
  ...
)

Arguments

path	File path of MODIS swath with exact sub-dataset specification.
cellsize	numeric(1). Cell size (spatial resolution) of output rectilinear grid raster.
threshold	numeric(1). Maximum distance to fill gaps if occur.
crs	integer(1)/character(1). Coordinate system definition. Should be compatible with EPSG codes or WKT2. See terra::crs and sf::st_crs / EPSG
...	For internal use.

Value

a stars object

Note

This function handles one file at a time.

Author(s)

Insang Song

See Also

terra::rectify

Examples

## NOTE: Example is wrapped in `\dontrun{}` as function requires a large
##       amount of data which is not included in the package.
## Not run: 
mod06l2_warp <- process_modis_warp(
  path = paste0(
    "HDF4_EOS:EOS_SWATH:",
    list.files(
      "./data/mod06l2",
      full.names = TRUE,
      pattern = ".hdf"
    )[1],
    ":mod06:Cloud_Fraction"
  ),
  cellsize = 0.1,
  threshold = 0.4,
  crs = 4326
)

## End(Not run)

amadeus documentation built on April 4, 2025, 12:21 a.m.