sgs::raster::GDALRasterWrapper

#include <raster.h>

Public Member Functions
	GDALRasterWrapper (std::string filename, std::string projDBPath)
	GDALRasterWrapper (GDALDataset *p_dataset, std::vector< void * > bands)
	GDALRasterWrapper (GDALDataset *p_dataset)
	GDALRasterWrapper (py::buffer buffer, std::vector< double > geotransform, std::string projection, std::vector< double > nanVals, std::vector< std::string > names, std::string projDBPath)
	~GDALRasterWrapper ()
void	close (void)
GDALDataset *	getDataset ()
std::string	getDriver ()
std::string	getFullProjectionInfo ()
std::string	getCRS ()
int	getWidth ()
int	getHeight ()
int	getBandCount ()
double	getXMax ()
double	getXMin ()
double	getYMax ()
double	getYMin ()
double	getPixelWidth ()
double	getPixelHeight ()
std::vector< std::string >	getBands ()
double *	getGeotransform ()
double	getBandNoDataValue (int band)
py::buffer	getRasterBandAsMemView (int width, int height, int band)
void	releaseBandBuffers (void)
GDALRasterBand *	getRasterBand (int band)
void *	getRasterBandBuffer (int band)
GDALDataType	getRasterBandType (int band)
size_t	getRasterBandTypeSize (int band)
void	write (std::string filename)
void	setTempDir (std::string tempDir)
std::string	getTempDir ()
std::vector< double >	getGeotransformArray ()
std::string	getDataType ()

Detailed Description

Wrapper class for a GDAL dataset containing a raster image.

This class provides getter methods for important raster data and metadata, as well as a way to access the raster as an array.

Memory is controlled using either a smart pointer (in the case of the dataset) or CPLMalloc and CPLFree (in the case of the raster image). The function GDALDataset::RasterIO() function should do the windowing for us behind the scenes, meaning we don't have to worry about physical memory size when allocating for large raster images.

The raster buffer contains all of the raster bands and can be indexed in Python with: [band][y][x] and in C++ with: [band * size * width * height + y * size * width + x * size]

The buffer is exposed to the Python side of the application using a py::buffer, and it's exposed to the C++ side of the application using a void *. The expectation is that this void pointer will be cast to another data type pointer as required.

Constructor & Destructor Documentation

GDALRasterWrapper() [1/4]

sgs::raster::GDALRasterWrapper::GDALRasterWrapper ( std::string filename, std::string projDBPath )

inline

Constructor for GDALRasterWrapper class. Creates GDALDataset using drivers and given file, then calls createFromDataset() passing the created object. Set the search path for the proj.db file, because this function may be the first called from the Python side of the application, meaning this instance of GDAL may not have found a proj.db file yet.

Parameters

std::string	filename
std::string	projDBPath

GDALRasterWrapper() [2/4]

sgs::raster::GDALRasterWrapper::GDALRasterWrapper ( GDALDataset * p_dataset, std::vector< void * > bands )

inline

Constructor for GDALRasterWrapper class if an in-memory dataset has already been created. The bands (already read and allocated) are passed as the second parameter. Calls createFromDataset() passing p_dataset parameter, and sets internal raster band parameters accordingly.

Parameters

GDALDataset	*p_dataset GDAL raster dataset
std::vector<void	*> raster bands

GDALRasterWrapper() [3/4]

sgs::raster::GDALRasterWrapper::GDALRasterWrapper ( GDALDataset * p_dataset )

inline

Constructor for GDALRasterWrapper class using just a GDAL dataset pointer, by calling createFromDataset().

Parameters

GDALDataset

*p_dataset GDAL raster dataset

GDALRasterWrapper() [4/4]

sgs::raster::GDALRasterWrapper::GDALRasterWrapper ( py::buffer buffer, std::vector< double > geotransform, std::string projection, std::vector< double > nanVals, std::vector< std::string > names, std::string projDBPath )

inline

Constructor for generating a GDALRasterWrapper from a numpy array and metadata. The numpy array is passed in the form of a py::buffer. Set the search path for the proj.db file, because this function may be the first called from the Python side of the application, meaning this instance of GDAL may not have found a proj.db file yet.

Parameters

py::buffer	buffer
std::vector<double>	geotransform
std::string	projection
std::vector<double>	nanVals
std::vector<std::string>	names
std::string	projDBPath

~GDALRasterWrapper()

sgs::raster::GDALRasterWrapper::~GDALRasterWrapper ( )

inline

Deconstructor for GDALRasterWrapper class. This method calls CPLFree() on any allocated raster buffers.

Member Function Documentation

close()

void sgs::raster::GDALRasterWrapper::close ( void )

inline

This is a copy of the deconstructor, it cleans up the all of the heap allocations which the class has made. This is meant to be called by the Python side of the application.

In the case where the used tries to continue to use the object after it has been cleaned up, there will be undefined behavior.

For this reason, there is a check to ensure no members of this object are accessed after it has been deleted from within the Pyhton code.

getBandCount()

int sgs::raster::GDALRasterWrapper::getBandCount ( )

inline

Getter method for the number of raster bands.

Returns

int

getBandNoDataValue()

double sgs::raster::GDALRasterWrapper::getBandNoDataValue ( int band )

inline

Getter method for a specific (0-indexed) bands nodata value.

Returns

double

getBands()

std::vector< std::string > sgs::raster::GDALRasterWrapper::getBands ( )

inline

Getter method for raster band names. Bands occur in order, meaning bands[0] corresponds to band 1, bands[1] to band 2, etc.

Returns

std::vector<std::string>

getCRS()

std::string sgs::raster::GDALRasterWrapper::getCRS ( )

inline

Get the CRS name from the OGRSpatialReference object

Returns

std::string

getDataset()

GDALDataset * sgs::raster::GDALRasterWrapper::getDataset ( )

inline

Getter method for wrapped dataset.

Returns

GDALDataset *

getDataType()

std::string sgs::raster::GDALRasterWrapper::getDataType ( )

inline

Gets the data type of the whole raster. If different bands have different types, returns "".

This is meant to be used by the Python side of the applications, specifically when converting from an sgs object to another Python geospatial library object.

Returns

std::string

getDriver()

std::string sgs::raster::GDALRasterWrapper::getDriver ( )

inline

Getter method for the raster driver.

Returns

std::string

getFullProjectionInfo()

std::string sgs::raster::GDALRasterWrapper::getFullProjectionInfo ( )

inline

Getter method for the full projection information as wkt.

Returns

std::string

getGeotransform()

double * sgs::raster::GDALRasterWrapper::getGeotransform ( )

inline

Getter method for geotransform.

Returns

double *

getGeotransformArray()

std::vector< double > sgs::raster::GDALRasterWrapper::getGeotransformArray ( )

inline

Getter method for the geotransform. Meant to be used by the python side of the application. Specifically, used when converting from an sgs object to another Python geospatial library object.

Returns

std::vector<double>

getHeight()

int sgs::raster::GDALRasterWrapper::getHeight ( )

inline

Getter method for the raster height.

Returns

int

getPixelHeight()

double sgs::raster::GDALRasterWrapper::getPixelHeight ( )

inline

Getter method for the pixel height. Scalar (absolute) value is given. see https://gdal.org/en/stable/tutorials/geotransforms_tut.html

Returns

double

getPixelWidth()

double sgs::raster::GDALRasterWrapper::getPixelWidth ( )

inline

Getter method for the pixel width. Scalar (absolute) value is given. see https://gdal.org/en/stable/tutorials/geotransforms_tut.html

Returns

double

getRasterBand()

GDALRasterBand * sgs::raster::GDALRasterWrapper::getRasterBand ( int band )

inline

Getter method for a GDALRasterBand in the raster, used by the C++ side of the application.

Parameters

int

band

Returns

GDALRasterBand *

getRasterBandAsMemView()

py::buffer sgs::raster::GDALRasterWrapper::getRasterBandAsMemView ( int width, int height, int band )

inline

Getter method for the raster image, used by the Python side of the application. This function allocates and reads a raster band if necessary, and uses py::memoryview::from_buffer() to create the buffer of the correct size/dimensions without copying data unecessarily.

This function requires that width and height be defined according to GDAL target_downscaling_factor rules. Otherwise, the incorrect amount of memory will be allocated. Information on target_downsampling_factor can be found here: https://gdal.org/en/stable/api/gdaldataset_cpp.html#classGDALDataset_1ae66e21b09000133a0f4d99baabf7a0ec

for py::memoryview::from_buffer() information see: https://pybind11.readthedocs.io/en/stable/advanced/pycpp/numpy.html#memory-view

Parameters

int	width
int	height
int	band

Returns

py::buffer python memoryview of the raster

getRasterBandBuffer()

void * sgs::raster::GDALRasterWrapper::getRasterBandBuffer ( int band )

inline

Getter method for the whole GDALRasterBand data buffer.

Parameters

int

Returns

void *

getRasterBandType()

GDALDataType sgs::raster::GDALRasterWrapper::getRasterBandType ( int band )

inline

Getter method for the pixel / raster data type.

Parameters

int

band

Returns

GDALDataType

getRasterBandTypeSize()

size_t sgs::raster::GDALRasterWrapper::getRasterBandTypeSize ( int band )

inline

Getter method for the pixel /raster data type size.

Parameters

int

band

Returns

size_t

getTempDir()

std::string sgs::raster::GDALRasterWrapper::getTempDir ( )

inline

Getter function for the rasters temporary directory.

Returns

std::string

getWidth()

int sgs::raster::GDALRasterWrapper::getWidth ( )

inline

Getter method for the raster width.

Returns

int

getXMax()

double sgs::raster::GDALRasterWrapper::getXMax ( )

inline

Getter method for the maximum x value in georeferenced coordinate space. see https://gdal.org/en/stable/tutorials/geotransforms_tut.html

Returns

double

getXMin()

double sgs::raster::GDALRasterWrapper::getXMin ( )

inline

Getter method for the minimum x value in georeferenced coordinate space. see https://gdal.org/en/stable/tutorials/geotransforms_tut.html

Returns

double

getYMax()

double sgs::raster::GDALRasterWrapper::getYMax ( )

inline

Getter method for the maximum y value in georeferenced coordinate space. see https://gdal.org/en/stable/tutorials/geotransforms_tut.html

Returns

double

getYMin()

double sgs::raster::GDALRasterWrapper::getYMin ( )

inline

Getter method for the minimum y value in georeferenced coordinate space. see https://gdal.org/en/stable/tutorials/geotransforms_tut.html

Returns

double

releaseBandBuffers()

void sgs::raster::GDALRasterWrapper::releaseBandBuffers ( void )

inline

This function is used when converting the sgs SpatialRaster Python class (which wraps this GDALRasterWrapper class) to a different data type, typically for a different geospatial package.

If the user desires the array as a numpy array, then the data must be passed as a buffer AND the ownership of the data must be released from the C++ object, so it is not cleaned up by the deconstructor when the C++ object is freed.

This is essentially a memory leak as far as the C++ code is concerned, however the numpy array will retain ownership and delete when required.

setTempDir()

void sgs::raster::GDALRasterWrapper::setTempDir ( std::string tempDir )

inline

Give the GDALRasterWrapper ownership of a temporary directory, for it to remove when deconstructed.

Parameters

std::string

tempDir

write()

void sgs::raster::GDALRasterWrapper::write ( std::string filename )

inline

Writes the raster to a specific file given by filename, by creating a copy of the GDALDatset.

Parameters

std::string

filename

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

• sgspy/utils/raster.h