Geo::GDAL: Geo::GDAL::Band Class Reference

Geo::GDAL::RasterAttributeTable Geo::GDAL::Band::AttributeTable ( scalar AttributeTable )

Parameters:

AttributeTable

[optional] A Geo::GDAL::RasterAttributeTable object.

Returns:: a new Geo::GDAL::RasterAttributeTable object, whose data is contained within the band.

list Geo::GDAL::Band::CategoryNames ( list names )

Parameters:

names

[optional]

Returns:

scalar Geo::GDAL::Band::Checksum	(	scalar	xoff = `0`,
		scalar	yoff = `0`,
		scalar	xsize = `undef`,
		scalar	ysize = `undef`
	)

Computes a checksum from the raster or a part of it.

Parameters:

	xoff
	yoff
	xsize
	ysize

Returns:: the checksum.

scalar Geo::GDAL::Band::ColorInterpretation ( scalar color_interpretation )

Note:: a.k.a. GetRasterColorInterpretation and GetColorInterpretation (get only and returns an integer), SetRasterColorInterpretation and SetColorInterpretation (set only and requires an integer)

Parameters:

color_interpretation

[optional] new color interpretation, one of @Geo::GDAL::Band::COLOR_INTERPRETATIONS

Returns:: color interpretation, one of @Geo::GDAL::Band::COLOR_INTERPRETATIONS

Geo::GDAL::ColorTable Geo::GDAL::Band::ColorTable ( scalar ColorTable )

Get or set the color table of this band.

Parameters:

ColorTable

[optional] a Geo::GDAL::ColorTable object

Returns:: a new Geo::GDAL::ColorTable object in a non-void context.

Geo::GDAL::Band::ComputeBandStats ( scalar samplestep = 1 )

Parameters:

samplestep

Returns:: arrayref Stats [mean, stddev]

Geo::GDAL::Band::ComputeRasterMinMax ( scalar approx_ok = 0 )

Returns:: arrayref MinMax = [min, max]

list Geo::GDAL::Band::ComputeStatistics ( scalar approx_ok )

Parameters:

approx_ok

Whether it is allowed to compute the statistics based on overviews or similar.

Returns:: a list ($min, $max, $mean, $stddev).

Geo::OGR::Layer Geo::GDAL::Band::Contours	(	scalar	DataSource,
		hashref	LayerConstructor,
		scalar	ContourInterval,
		scalar	ContourBase,
		listref	FixedLevels,
		scalar	NoDataValue,
		scalar	IDField,
		scalar	ElevField,
		scalar	callback,
		scalar	callback_data
	)

Generate contours for this raster band. This method can also be used with named parameters.

Note:: This method is a wrapper for ContourGenerate.

An example:

use Geo::GDAL;
$dem = Geo::GDAL::Open('dem.gtiff');
$contours = $dem->Band->Contours(ContourInterval => 10, ElevField => 'z');
$n = $contours->GetFeatureCount;

Parameters:

	DataSource	a Geo::OGR::DataSource object, default is a Memory data source
	LayerConstructor	data for Geo::OGR::DataSource::CreateLayer, default is {Name => 'contours'}
	ContourInterval	default is 100
	ContourBase	default is 0
	FixedLevels	a reference to a list of fixed contour levels, default is []
	NoDataValue	default is undef
	IDField	default is '', i.e., no field (the field is created if this is given)
	ElevField	default is '', i.e., no field (the field is created if this is given)
	callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
	callback_data	[optional]

Returns:

Geo::GDAL::Band::CreateMaskBand ( )

scalar Geo::GDAL::Band::DataType ( )

Returns:: a data type string (Byte, UInt16, Int16, UInt32, Int32, Float32, Float64, CInt16, CInt32, CFloat32, or CFloat64).

Geo::GDAL::Band::Fill	(	scalar	real_part,
		scalar	imag_part = `0.0`
	)

Fill the band with a constant value.

Parameters:

	real_part	Real component of fill value.
	imag_part	Imaginary component of fill value.

Geo::GDAL::Band::FillNodata	(	scalar	mask,
		scalar	max_search_dist = `10`,
		scalar	smoothing_iterations = `0`,
		scalar	options = `ref_to_anon_empty_hash`,
		scalar	callback,
		scalar	callback_data
	)

Note:: This is a wrapper for Geo::GDAL::FillNodata.

Parameters:

	mask	a mask band indicating pixels to be interpolated (zero valued)
	max_search_dist	[optional] the maximum number of pixels to search in all directions to find values to interpolate from.
	smoothing_iterations	[optional] the number of 3x3 smoothing filter passes to run (0 or more).
	options	[optional] A reference to a hash. No options have been defined so far for this algorithm.
	callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
	callback_data	[optional]

Documentation for GDAL algorithms

Geo::GDAL::Band::FlushCache ( )

Write cached data to disk. There is usually no need to call this method.

scalar Geo::GDAL::Band::GetBandNumber ( )

Note:: a.k.a. GetBand

Returns:: the number of this band.

list Geo::GDAL::Band::GetBlockSize ( )

Returns:: the size of a preferred i/o raster blocks as a list (width, height).

Geo::GDAL::ColorTable Geo::GDAL::Band::GetColorTable ( )

Note:: a.k.a. GetRasterColorTable, see also ColorTable

Returns:: a color table object.

list Geo::GDAL::Band::GetDefaultHistogram	(	scalar	force = `1`,
		scalar	callback = `undef`,
		scalar	callback_data = `undef`
	)

Parameters:

	force	true to force the computation
	callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
	callback_data	[optional]

Returns:: a list: ($min, $max, arrayref histogram).

Geo::GDAL::RasterAttributeTable Geo::GDAL::Band::GetDefaultRAT ( )

Deprecated:: use Geo::GDAL::Band::AttributeTable, which makes sure the band is not destroyed before the attribute table.

Returns:: a new Geo::GDAL::RasterAttributeTable object, whose data is contained within the band.

list Geo::GDAL::Band::GetHistogram ( hash parameters )

Compute histogram from the raster.

Parameters:

parameters

Named parameters:

Min the lower bound, default is -0.5
Max the upper bound, default is 255.5
Buckets the number of buckets in the histogram, default is 256
IncludeOutOfRange whether to use the first and last values in the returned list for out of range values, default is false; the bucket size is (Max-Min) / Buckets if this is false and (Max-Min) / (Buckets-2) if this is true
ApproxOK if histogram can be computed from overviews, default is false
Progress an optional progress function, the default is undef
ProgressData data for the progress function, the default is undef

Returns:: a list which contains the count of values in each bucket

Geo::GDAL::Band Geo::GDAL::Band::GetMaskBand ( )

scalar Geo::GDAL::Band::GetMaskFlags ( )

scalar Geo::GDAL::Band::GetMaximum ( )

Returns:: statistical minimum of the band or undef if statistics are not kept or computed.

scalar Geo::GDAL::Band::GetMinimum ( )

Returns:: statistical minimum of the band or undef if statistics are not kept or computed.

Geo::GDAL::Band Geo::GDAL::Band::GetOverview ( scalar band )

Parameters:

band

0..GetOverviewCount-1

Returns:: a new Geo::GDAL::Band object.

scalar Geo::GDAL::Band::GetOverviewCount ( )

Returns:: the number of overviews available of the band.

scalar Geo::GDAL::Band::GetRasterCategoryNames ( )

Note:: a.k.a. GetCategoryNames, see also CategoryNames

Returns:: names

list Geo::GDAL::Band::GetStatistics	(	scalar	approx_ok,
		scalar	force
	)

Parameters:

	approx_ok	Whether it is allowed to compute the statistics based on overviews or similar.
	force	Whether to force scanning of the whole raster.

Returns:: a list ($min, $max, $mean, $stddev).

Geo::GDAL::Band::HasArbitraryOverviews ( )

Returns:: true or false.

scalar Geo::GDAL::Band::NoDataValue ( scalar NoDataValue )

Note:: a.k.a. GetNoDataValue (get only), SetNoDataValue (set only)

Parameters:

NoDataValue

[optional] Get or set the no data value.

Note:: There does not exist a good way to clear the no data value. $band->NoDataValue(undef) does not do what you want.

Returns:: the nodata value.

scalar Geo::GDAL::Band::ReadRaster	(	scalar	xoff,
		scalar	yoff,
		scalar	xsize,
		scalar	ysize,
		scalar	buf_xsize = `undef`,
		scalar	buf_ysize = `undef`,
		scalar	buf_type = `undef`
	)

Parameters:

	xoff
	yoff
	xsize
	ysize
	buf_xsize
	buf_ysize
	buf_type

Returns:: the data in a binary buffer. Use the unpack function of Perl to get the data from the buffer.

listref Geo::GDAL::Band::ReadTile	(	scalar	xoff = `0`,
		scalar	yoff = `0`,
		scalar	xsize = `<width>`,
		scalar	ysize = `<height>`
	)

Usage example (print the data from a band):

print "@$_\n" for ( @{ $band->ReadTile() } );

Another usage example (process the data of a large dataset that has one band):

my($W,$H) = $dataset->Band(1)->Size();
my($xoff,$yoff,$w,$h) = (0,0,200,200);
while (1) {
    if ($xoff >= $W) {
        $xoff = 0;
        $yoff += $h;
        last if $yoff >= $H;
    }
    my $data = $dataset->Band(1)->ReadTile($xoff,$yoff,min($W-$xoff,$w),min($H-$yoff,$h));
    # add your data processing code here
    $dataset->Band(1)->WriteTile($data,$xoff,$yoff);
    $xoff += $w;
}

sub min {
    return $_[0] < $_[1] ? $_[0] : $_[1];
}

Parameters:

	xoff
	yoff
	xsize
	ysize

Returns:: a two-dimensional Perl array, organizes as data->[y][x], y = 0..height-1, x = 0..width-1.

Geo::GDAL::Band::ScaleAndOffset	(	scalar	scale,
		scalar	offset
	)

Scale and offset are used to transform raw pixel values into the units returned by GetUnits(). The conversion function is:

Units value = (raw value * scale) + offset

Returns:: ($scale, $offset)

Since:: version 1.9 of the bindings.

Geo::GDAL::Band::SetColorTable ( scalar ColorTable )

Note:: a.k.a. SetRasterColorTable, see also ColorTable

Parameters:

ColorTable

A color table object.

list Geo::GDAL::Band::SetDefaultHistogram	(	scalar	min,
		scalar	max,
		scalar	histogram
	)

Parameters:

	min
	max
	histogram	reference to an array containing the histogram

Geo::GDAL::Band::SetDefaultRAT ( scalar AttributeTable )

Parameters:

AttributeTable

a Geo::GDAL::RasterAttributeTable object

Geo::GDAL::Band::SetRasterCategoryNames ( scalar names )

Note:: a.k.a. SetCategoryNames, see also CategoryNames

Parameters:

names

Geo::GDAL::Band::SetStatistics	(	scalar	min,
		scalar	max,
		scalar	mean,
		scalar	stddev
	)

Save the statistics of the band if possible (the format can save arbitrary metadata).

Parameters:

	min
	max
	mean
	stddev

list Geo::GDAL::Band::Size ( )

Returns:: the size of the band as a list (width, height).

Geo::GDAL::Band::Unit ( scalar type )

Parameters:

type

[optional] the unit (a string).

Returns:: the unit (a string).

Since:: version 1.9 of the bindings.

Geo::GDAL::Band::WriteRaster	(	scalar	xoff,
		scalar	yoff,
		scalar	xsize,
		scalar	ysize,
		scalar	buf,
		scalar	buf_xsize = `undef`,
		scalar	buf_ysize = `undef`,
		scalar	buf_type = `undef`
	)

Parameters:

	xoff
	yoff
	xsize
	ysize
	buf	The data to be written in a binary buffer. Use the pack function of Perl to prepare a buffer.
	buf_xsize
	buf_ysize
	buf_type

Geo::GDAL::Band::WriteTile	(	scalar	data,
		scalar	xoff = `0`,
		scalar	yoff = `0`
	)

Parameters:

	data	A two-dimensional Perl array, organizes as data->[y][x], y = 0..height-1, x = 0..width-1.
	xoff
	yoff

list Geo::GDAL::Band::COLOR_INTERPRETATIONS

Geo::GDAL::Band::XSize

scalar (access as $band->{XSize})

Geo::GDAL::Band::YSize

scalar (access as $band->{YSize})


Public Object Methods
scalar	GetBandNumber ()
scalar	DataType ()
list	Size ()
list	GetBlockSize ()
scalar	ColorInterpretation (scalar color_interpretation)
scalar	NoDataValue (scalar NoDataValue)
	Unit (scalar type)
	ScaleAndOffset (scalar scale, scalar offset)
scalar	GetMinimum ()
scalar	GetMaximum ()
list	ComputeStatistics (scalar approx_ok)
list	GetStatistics (scalar approx_ok, scalar force)
	SetStatistics (scalar min, scalar max, scalar mean, scalar stddev)
scalar	GetOverviewCount ()
Geo::GDAL::Band	GetOverview (scalar band)
	HasArbitraryOverviews ()
scalar	Checksum (scalar xoff=0, scalar yoff=0, scalar xsize=undef, scalar ysize=undef)
	ComputeRasterMinMax (scalar approx_ok=0)
	ComputeBandStats (scalar samplestep=1)
	Fill (scalar real_part, scalar imag_part=0.0)
	WriteTile (scalar data, scalar xoff=0, scalar yoff=0)
listref	ReadTile (scalar xoff=0, scalar yoff=0, scalar xsize=< width >, scalar ysize=< height >)
	WriteRaster (scalar xoff, scalar yoff, scalar xsize, scalar ysize, scalar buf, scalar buf_xsize=undef, scalar buf_ysize=undef, scalar buf_type=undef)
scalar	ReadRaster (scalar xoff, scalar yoff, scalar xsize, scalar ysize, scalar buf_xsize=undef, scalar buf_ysize=undef, scalar buf_type=undef)
list	GetHistogram (hash parameters)
list	GetDefaultHistogram (scalar force=1, scalar callback=undef, scalar callback_data=undef)
list	SetDefaultHistogram (scalar min, scalar max, scalar histogram)
	FlushCache ()
Geo::GDAL::ColorTable	ColorTable (scalar ColorTable)
Geo::GDAL::ColorTable	GetColorTable ()
	SetColorTable (scalar ColorTable)
	CreateMaskBand ()
Geo::GDAL::Band	GetMaskBand ()
scalar	GetMaskFlags ()
list	CategoryNames (list names)
scalar	GetRasterCategoryNames ()
	SetRasterCategoryNames (scalar names)
Geo::GDAL::RasterAttributeTable	AttributeTable (scalar AttributeTable)
Geo::GDAL::RasterAttributeTable	GetDefaultRAT ()
	SetDefaultRAT (scalar AttributeTable)
Geo::OGR::Layer	Contours (scalar DataSource, hashref LayerConstructor, scalar ContourInterval, scalar ContourBase, listref FixedLevels, scalar NoDataValue, scalar IDField, scalar ElevField, scalar callback, scalar callback_data)
	FillNodata (scalar mask, scalar max_search_dist=10, scalar smoothing_iterations=0, scalar options=ref_to_anon_empty_hash, scalar callback, scalar callback_data)
Public Attributes
list	COLOR_INTERPRETATIONS
	XSize
	YSize

Geo::GDAL::Band Class Reference

Public Object Methods

Public Attributes

Member Function Documentation

Member Data Documentation