source_cube: Functions to instantiate a new cube from a source

Description

These functions provide an API to instantiate a new cube object and access/retrieve information from services or local files to fill cube attributes.

A cube is formed by images (items) organized in tiles. To create a sits cube object (a tibble), a set of functions are called in order to retrieve metadata.

.source_cube() is called to start the cube creation from a source.

.source_item_get_date() retrieves the date of an item (a set of images from different bands that forms a scene).

.source_item_get_hrefs() retrieves the paths or URLs of each file bands of an item.

.source_item_get_bands() retrieves the bands present in an item.

.source_item_get_resolutions() retrieves the supported resolutions of an item (for each band).

.source_items_new() this function is called to create an items object. In case of Web services, this function is responsible for making the Web requests to the server.

Selection of items from specific bands by the user.

.source_items_bands_select() is a filter of bands and selects the items' bands that will be in sits cube.

.source_items_fileinfo() creates the fileinfo specification from items object.

.source_items_tiles_group() organizes items by tiles and arrange items in each tile by date.

.source_items_get_sensor() retrieves the sensor from items object.

.source_items_get_satellite() retrieves the satellite name (platform) from items object.

.source_items_tile_get_crs() retrieves the CRS string from items.

.source_items_tile_get_name() retrieves the tile name from items.

.source_items_tile_get_bbox() retrieves the bounding box from items of a tile.

.source_items_tile_get_size() retrieves the size (in pixels) from items of a tile.

.source_cube() is called to create a data cubes tile, that is, a row in sits data cube.

Usage

.source_cube(source, ...)
.source_item_get_date(source, item, ..., collection = NULL)
.source_item_get_hrefs(source, item, ..., collection = NULL)
.source_item_get_bands(source, item, ..., collection = NULL)
.source_item_get_resolutions(source, item, ..., collection = NULL)
.source_items_new(source, collection, ...)
.source_items_bands_select(source, collection, items, bands, ...)
.source_items_fileinfo(source, items, ..., collection = NULL)
.source_items_tiles_group(source, items, ..., collection = NULL)
.source_items_get_sensor(source, items, ..., collection = NULL)
.source_items_get_satellite(source, items, ..., collection = NULL)
.source_items_tile_get_crs(source, tile_items, ..., collection = NULL)
.source_items_tile_get_name(source, tile_items, ..., collection = NULL)
.source_items_tile_get_bbox(source, tile_items, ..., collection = NULL)
.source_items_tile_get_size(source, tile_items, ..., collection = NULL)
.source_items_cube(source, collection, name, items, file_info, ...)

Arguments

source

A character value referring to a valid data source.

...

Additional parameters.

collection

A character value referring to a collection of the source.

items

Any object referring to the images bands (scenes) that compose a cube.

bands

A character with bands to be select in items object.

name

A character with cube name.

file_info

A tibble that organizes the metadata about each file in the tile: date, band, resolution, and path (or URL).

Value

The values returned by each function are described as follows.

.source_cube() returns a sits tibble with cube metadata.

.source_item_get_date() returns a Date value.

.source_item_get_hrefs() returns a character vector containing paths to each image band of an item.

.source_item_get_bands() returns a character vector containing bands name of an item.

.source_item_get_resolutions() returns a named list with numeric vectors containing the supported resolutions of an item.

.source_items_new() returns any object referring the images of a sits cube.

A STACItemCollection object returned by rstac with items selected.

.source_items_bands_select() returns the same object as items with selected bands.

.source_items_fileinfo() returns a tibble containing sits cube.

.source_items_tiles_group() returns a list of items.

.source_items_get_sensor() returns a character value.

.source_items_get_satellite() returns a character value.

.source_items_tile_get_crs() returns a character value.

.source_items_tile_get_name() returns a character value.

.source_items_tile_get_bbox() returns a numeric vector with 4 elements (xmin, ymin, xmax, ymax).

.source_items_tile_get_size() returns a numeric vector with 2 elements (nrows, ncols).

.source_cube() returns a tibble containing a sits cube tile (one row).