GDALGeoTransform Class Reference

Class that encapsulates a geotransform matrix. More...

#include <gdal_geotransform.h>

Public Member Functions
	GDALGeoTransform ()=default
	Default constructor for an identity geotransformation matrix.
	GDALGeoTransform (const double coeffs[6])
	Constructor from a array of 6 double.
	GDALGeoTransform (double xorigIn, double xscaleIn, double xrotIn, double yorigIn, double yrotIn, double yscaleIn)
	Constructor from 6 double values.
template<typename T>
double	operator[] (T idx) const
	Element accessor.
template<typename T>
double &	operator[] (T idx)
	Element accessor.
bool	operator== (const GDALGeoTransform &other) const
	Equality test operator.
bool	operator!= (const GDALGeoTransform &other) const
	Inequality test operator.
const double *	data () const
	Cast to const double*.
double *	data ()
	Cast to double*.
void	Apply (double dfPixel, double dfLine, double *pdfGeoX, double *pdfGeoY) const
	Apply GeoTransform to x/y coordinate.
bool	Apply (const OGREnvelope &env, GDALRasterWindow &window) const
	Apply a (inverse) geotransform to an OGREnvelope in georeferenced coordinates.
bool	Apply (const GDALRasterWindow &window, OGREnvelope &env) const
	Apply a geotransform to a GDALRasterWindow in pixel/line coordinates.
std::pair< double, double >	Apply (double dfPixel, double dfLine) const
	Apply GeoTransform to x/y coordinate.
bool	GetInverse (GDALGeoTransform &inverse) const
	Invert Geotransform.
void	Rescale (double dfXRatio, double dfYRatio)
	Rescale a geotransform by multiplying its scale and rotation terms by the provided ratios.
bool	IsAxisAligned () const
	Check whether the geotransform has a rotation component.

Public Attributes
double	xorig = 0
	X value of the origin of the raster.
double	xscale = 1
	X scale factor.
double	xrot = 0
	X rotation factor.
double	yorig = 0
	Y value of the origin of the raster.
double	yrot = 0
	Y rotation factor.
double	yscale = 1
	Y scale factor.

Detailed Description

Class that encapsulates a geotransform matrix.

It contains 6 coefficients expressing an affine transformation from (column, line) raster space to (X, Y) georeferenced space, such that

X = xorig + column * xscale + line * xrot;
Y = yorig + column * yrot   + line * yscale;

The default value is the identity transformation.

Since

3.12

Member Function Documentation

Apply() [1/4]

bool GDALGeoTransform::Apply	(	const GDALRasterWindow &	window,
		OGREnvelope &	env ) const

Apply a geotransform to a GDALRasterWindow in pixel/line coordinates.

Parameters

	window	A window in pixel/line coordinates
[out]	env	An envelope in georeferenced coordinates

Returns

true if the geotransform was successfully applied

Apply() [2/4]

bool GDALGeoTransform::Apply	(	const OGREnvelope &	env,
		GDALRasterWindow &	window ) const

Apply a (inverse) geotransform to an OGREnvelope in georeferenced coordinates.

Parameters

	env	An envelope in georeferenced coordinates
[out]	window	A window in pixel/line coordinates

Returns

true if the geotransform was successfully applied

Apply() [3/4]

std::pair< double, double > GDALGeoTransform::Apply ( double dfPixel, double dfLine ) const

inline

Apply GeoTransform to x/y coordinate.

Applies the following computation, converting a (pixel, line) coordinate into a georeferenced (geo_x, geo_y) location.

out.first = padfGeoTransform[0] + dfPixel * padfGeoTransform[1]
                                 + dfLine  * padfGeoTransform[2];
out.second = padfGeoTransform[3] + dfPixel * padfGeoTransform[4]
                                 + dfLine  * padfGeoTransform[5];

Parameters

dfPixel	Input pixel position.
dfLine	Input line position.

Returns

output location as a (geo_x, geo_y) pair

Apply() [4/4]

void GDALGeoTransform::Apply ( double dfPixel, double dfLine, double * pdfGeoX, double * pdfGeoY ) const

inline

Apply GeoTransform to x/y coordinate.

Applies the following computation, converting a (pixel, line) coordinate into a georeferenced (geo_x, geo_y) location.

*pdfGeoX = padfGeoTransform[0] + dfPixel * padfGeoTransform[1]
                               + dfLine  * padfGeoTransform[2];
*pdfGeoY = padfGeoTransform[3] + dfPixel * padfGeoTransform[4]
                               + dfLine  * padfGeoTransform[5];

Parameters

dfPixel	Input pixel position.
dfLine	Input line position.
pdfGeoX	output location where geo_x (easting/longitude) location is placed.
pdfGeoY	output location where geo_y (northing/latitude) location is placed.

GetInverse()

bool GDALGeoTransform::GetInverse ( GDALGeoTransform & inverse ) const

inline

Invert Geotransform.

This function will invert a standard 3x2 set of GeoTransform coefficients. This converts the equation from being pixel to geo to being geo to pixel.

Parameters

[out]

inverse

Output geotransform

Returns

true on success or false if the equation is uninvertable.

operator[]() [1/2]

template<typename T>

double & GDALGeoTransform::operator[] ( T idx )

inline

Element accessor.

idx must be in [0,5] range

operator[]() [2/2]

template<typename T>

double GDALGeoTransform::operator[] ( T idx ) const

inline

Element accessor.

idx must be in [0,5] range

Rescale()

void GDALGeoTransform::Rescale ( double dfXRatio, double dfYRatio )

inline

Rescale a geotransform by multiplying its scale and rotation terms by the provided ratios.

This is typically used to compute the geotransform matrix of an overview dataset from the full resolution dataset, where the ratios are the size of the full resolution dataset divided by the size of the overview.

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The documentation for this class was generated from the following files:

• gdal_geotransform.h
• gdal_misc.cpp