GDALRasterBand-class: Class "GDALRasterBand"

In rgdal: Bindings for the 'Geospatial' Data Abstraction Library

Class "GDALRasterBand"

Description

Returns a two-dimensional array with data from a raster band, used internally within functions

Usage

getRasterData(dataset, band = NULL, offset = c(0, 0),
              region.dim = dim(dataset), output.dim = region.dim,
              interleave = c(0, 0), as.is = FALSE, list_out=FALSE) 

getRasterTable(dataset, band = NULL, offset = c(0, 0), 
  region.dim = dim(dataset))

getProjectionRef(dataset, OVERRIDE_PROJ_DATUM_WITH_TOWGS84 = NULL,
 enforce_xy = NULL, get_source_if_boundcrs=TRUE)

getRasterBand(dataset, band = 1)

getRasterBlockSize(raster)

toSigned(x, base)

toUnSigned(x, base)

get_OVERRIDE_PROJ_DATUM_WITH_TOWGS84()
set_OVERRIDE_PROJ_DATUM_WITH_TOWGS84(value)

Arguments

dataset	An object inheriting from class 'GDALReadOnlyDataset'
band	The band number (1-based) to read from
offset	Number of rows and columns from the origin (usually the upper left corner) to begin reading from; presently ordered (y,x) - this may change
region.dim	The number of rows and columns to read from the dataset; presently ordered (y,x) - this may change
output.dim	Number of rows and columns in the output data; if smaller than region.dim the data will be subsampled
interleave	Element and row stride while reading data; rarely needed
as.is	If false, scale the data to its natural units; if the case of thematic data, return the data as factors
list_out	default FALSE, return array, if TRUE, return a list of vector bands
raster	An object of class GDALRasterBand
x	integer variable for conversion
base	If Byte input, 8, if Int16 or UInt16, 16
OVERRIDE_PROJ_DATUM_WITH_TOWGS84	logical value, default NULL, which case the cached option set by set_OVERRIDE_PROJ_DATUM_WITH_TOWGS84 is used. Ignored if the GDAL version is less than “1.8.0” or if the CPLConfigOption variable is already set
enforce_xy	(PROJ6+/GDAL3+) either use global setting (default NULL) or override policy for coordinate ordering easting/x as first axis, northing/y as second axis.
get_source_if_boundcrs	The presence of the +towgs84= key in a Proj4 string projargs= argument value may promote the output WKT2 CRS to BOUNDCRS for PROJ >= 6 and GDAL >= 3, which is a coordinate operation from the input datum to WGS84. This is often unfortunate, so a PROJ function is called through rgdal to retrieve the underlying source definition.
value	logical value to set OVERRIDE_PROJ_DATUM_WITH_TOWGS84

Details

getRasterData:

retrieves data from the dataset as an array or list of bands; will try to convert relevant bands to factor if category names are available in the GDAL driver when returning a list.

getRasterTable:

retrieves data from the dataset as data frame.

getProjectionRef:

returns the geodetic projection in Well Known Text format.

getRasterBand:

returns a raster band

getRasterBlockSize:

returns the natural block size of the raster band. Use this for efficient tiled IO.

toSigned:

used to convert a band read as unsigned integer to signed integer

toUnSigned:

used to convert a band read as signed integer to unsigned integer

Objects from the Class

Objects can be created by calls of the form new("GDALRasterBand", dataset, band).

Slots

handle:

Object of class "externalptr", from class "GDALMajorObject", used internally; not for public consumption

Extends

Class "GDALMajorObject", directly.

Methods

dim

signature(x = "GDALRasterBand"): ...

initialize

signature(.Object = "GDALRasterBand"): ...

Note

The OVERRIDE_PROJ_DATUM_WITH_TOWGS84 argument is used to revert GDAL behaviour to pre-1.8.0 status; from 1.8.0, any input datum may be discarded if the input also includes a towgs84 tag in conversion to the PROJ.4 representation, see https://trac.osgeo.org/gdal/ticket/4880 and https://lists.osgeo.org/pipermail/gdal-dev/2012-November/034550.html. The cached value of OVERRIDE_PROJ_DATUM_WITH_TOWGS84 will also be used in open.SpatialGDAL, sub.GDROD, and asGDALROD_SGDF, which do not have a suitable argument

Author(s)

Timothy H. Keitt, modified by Roger Bivand

See Also

See also GDALDriver-class, GDALDataset-class, GDALTransientDataset-class

Examples

logo <- system.file("pictures/logo.jpg", package="rgdal")[1]
x <- new("GDALReadOnlyDataset", logo)
plot(density(getRasterTable(x)$band1))
GDAL.close(x)

rgdal documentation built on June 7, 2023, 5:09 p.m.