A geographic (longitude-latitude) spatial reference system. More...

#include <srs.h>

Inheritance diagram for gis::srs::Geographic_srs:

Public Member Functions
	Geographic_srs ()

Srs_type	srs_type () const override
	Get the type of spatial reference system: projected, geometric, etc. More...

Spatial_reference_system *	clone () override
	Clone the object. More...

virtual bool	init (srid_t srid, wkt_parser::Geographic_cs *g)
	Initialize from parse tree. More...

bool	has_towgs84 () const override
	Checks if this SRS has valid Bursa Wolf parameters. More...

bool	is_wgs84_based () const override
	Checks if this SRS is WGS 84 or a projection based on WGS 84. More...

Axis_direction	axis_direction (const int axis) const override
	Retrieve the axis direction of the spatial reference system. More...

std::string	partial_proj4_parameters () const

double	semi_major_axis () const

double	inverse_flattening () const

double	linear_unit () const override
	Retrieve how long the unit of the spatial reference system is in meters. More...

double	angular_unit () const override
	Retrieve the angular unit relative to radians. More...

double	prime_meridian () const override
	Retrieve the prime meridian relative to Greenwich. More...

bool	can_be_modified_to (const Spatial_reference_system &srs) const override
	Checks if this SRS can be changed to another SRS without causing computational incompatibilities. More...

std::string	proj4_parameters () const override
	Retrieve the proj4 parameter string. More...

Public Member Functions inherited from gis::srs::Spatial_reference_system
	Spatial_reference_system ()=default

	Spatial_reference_system (const Spatial_reference_system &)=default

	Spatial_reference_system (Spatial_reference_system &&)=default

virtual	~Spatial_reference_system ()=default

Private Attributes
double	m_semi_major_axis
	Semi-major axis of ellipsoid. More...

double	m_inverse_flattening
	Inverse flattening of ellipsoid. More...

double	m_towgs84 [7]
	Bursa Wolf transformation parameters used to transform to WGS84. More...

double	m_prime_meridian
	Longitude of the prime meridian relative to the Greenwich Meridian (measured in m_angular_unit). More...

double	m_angular_unit
	Conversion factor for the angular unit relative to radians. More...

Axis_direction	m_axes [2]
	Direction of x and y axis, respectively. More...

bool	m_is_wgs84
	Whether this SRS is WGS 84. More...

Detailed Description

A geographic (longitude-latitude) spatial reference system.

Constructor & Destructor Documentation

◆ Geographic_srs()

gis::srs::Geographic_srs::Geographic_srs ( )

inline

Member Function Documentation

◆ angular_unit()

double gis::srs::Geographic_srs::angular_unit ( ) const

inlineoverridevirtual

Retrieve the angular unit relative to radians.

Returns: Conversion factor.

Implements gis::srs::Spatial_reference_system.

◆ axis_direction()

Axis_direction gis::srs::Geographic_srs::axis_direction ( const int axis ) const

inlineoverridevirtual

Retrieve the axis direction of the spatial reference system.

Parameters

axis	axis number, zero indexed

Returns: Axis direction

Implements gis::srs::Spatial_reference_system.

◆ can_be_modified_to()

bool gis::srs::Geographic_srs::can_be_modified_to ( const Spatial_reference_system & srs ) const

overridevirtual

Checks if this SRS can be changed to another SRS without causing computational incompatibilities.

This means checking that all values in the two SRSs that affect computations are the same. The syntax of the SRS definitions may still vary, e.g., by using different names or by having different authority codes.

In some cases, e.g., unknown projection methods, we don't know how to compare the two SRSs. In that case, we fail by saying that the SRSs are not the same.

The operation is not commutative. The SRS parameter is allowed to have a TOWGS84 specification even though this object doesn't. The opposite is not necessarily true. If this object lacks TOWGS84 information, transformation operations are forbidden on this SRS. Adding that possibility changes what computations are available, but it doesn't change the result of any computation that can currently be done.

An SRS that is currently identified as WGS 84 may both add and remove TOWGS84 information as long as the parameters are all 0. Adding a non-all-zero TOWGS84 clause to a WGS 84 SRS is not allowed.

Parameters

srs	The SRS to compare with.

Return values

true	The two SRSs are semantically the same.
false	The two SRSs are semantically different, or we don't know how to compare them.

Implements gis::srs::Spatial_reference_system.

◆ clone()

Spatial_reference_system * gis::srs::Geographic_srs::clone ( )

inlineoverridevirtual

Clone the object.

Returns: A new Spatial_reference_system object

Implements gis::srs::Spatial_reference_system.

◆ has_towgs84()

bool gis::srs::Geographic_srs::has_towgs84 ( ) const

inlineoverridevirtual

Checks if this SRS has valid Bursa Wolf parameters.

Return values

true	Transformation parameters are specified.
false	Transformation parameters are not specified.

Implements gis::srs::Spatial_reference_system.

◆ init()

bool gis::srs::Geographic_srs::init	(	gis::srid_t	srid,
		wkt_parser::Geographic_cs *	g
	)

virtual

Initialize from parse tree.

Parameters

[in]	srid	Spatial reference system ID to use when reporting errors
[in]	g	Parser output

Return values

true	An error has occurred. The error has been flagged.
false	Success

◆ inverse_flattening()

double gis::srs::Geographic_srs::inverse_flattening ( ) const

inline

◆ is_wgs84_based()

bool gis::srs::Geographic_srs::is_wgs84_based ( ) const

inlineoverridevirtual

Checks if this SRS is WGS 84 or a projection based on WGS 84.

Return values

true	This SRS is WGS 84 or a projection of WGS 84.
false	This SRS is neither WGS 84 or a projection of WGS 84.

Implements gis::srs::Spatial_reference_system.

◆ linear_unit()

double gis::srs::Geographic_srs::linear_unit ( ) const

inlineoverridevirtual

Retrieve how long the unit of the spatial reference system is in meters.

Returns: Conversion factor

Implements gis::srs::Spatial_reference_system.

◆ partial_proj4_parameters()

std::string gis::srs::Geographic_srs::partial_proj4_parameters ( ) const

◆ prime_meridian()

double gis::srs::Geographic_srs::prime_meridian ( ) const

inlineoverridevirtual

Retrieve the prime meridian relative to Greenwich.

The prime meridian is returned in the angular unit of the SRS. Positive numbers are East of Greenwich.

See also: angular_unit

Returns: Prime meridian.

Implements gis::srs::Spatial_reference_system.

◆ proj4_parameters()

std::string gis::srs::Geographic_srs::proj4_parameters ( ) const

overridevirtual

Retrieve the proj4 parameter string.

If the SRS can't be represented as a proj4 parameter string, an empty string is returned.

Returns: Proj4 parameter string or empty string.

Reimplemented from gis::srs::Spatial_reference_system.

◆ semi_major_axis()

double gis::srs::Geographic_srs::semi_major_axis ( ) const

inline

◆ srs_type()

Srs_type gis::srs::Geographic_srs::srs_type ( ) const

inlineoverridevirtual

Get the type of spatial reference system: projected, geometric, etc.

Returns: SRS type

Implements gis::srs::Spatial_reference_system.

Member Data Documentation

◆ m_angular_unit

double gis::srs::Geographic_srs::m_angular_unit

private

Conversion factor for the angular unit relative to radians.

◆ m_axes

Axis_direction gis::srs::Geographic_srs::m_axes[2]

private

Direction of x and y axis, respectively.

◆ m_inverse_flattening

double gis::srs::Geographic_srs::m_inverse_flattening

private

Inverse flattening of ellipsoid.

◆ m_is_wgs84

bool gis::srs::Geographic_srs::m_is_wgs84

private

Whether this SRS is WGS 84.

◆ m_prime_meridian

double gis::srs::Geographic_srs::m_prime_meridian

private

Longitude of the prime meridian relative to the Greenwich Meridian (measured in m_angular_unit).

Positive values are East of Greenwich.

◆ m_semi_major_axis

double gis::srs::Geographic_srs::m_semi_major_axis

private

Semi-major axis of ellipsoid.

◆ m_towgs84

double gis::srs::Geographic_srs::m_towgs84[7]

private

Bursa Wolf transformation parameters used to transform to WGS84.

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

sql/gis/srs/srs.h
sql/gis/srs/srs.cc

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Geographic_srs()

Member Function Documentation

◆ angular_unit()

◆ axis_direction()

◆ can_be_modified_to()

◆ clone()

◆ has_towgs84()

◆ init()

◆ inverse_flattening()

◆ is_wgs84_based()

◆ linear_unit()

◆ partial_proj4_parameters()

◆ prime_meridian()

◆ proj4_parameters()

◆ semi_major_axis()

◆ srs_type()

Member Data Documentation

◆ m_angular_unit

◆ m_axes

◆ m_inverse_flattening

◆ m_is_wgs84

◆ m_prime_meridian

◆ m_semi_major_axis

◆ m_towgs84