A Mercator (variant A) projection, alias Mercator (EPSG 9804). More...

#include <srs.h>

Inheritance diagram for gis::srs::Mercator_variant_a_srs:

Public Member Functions
	Mercator_variant_a_srs ()

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

bool	init (srid_t srid, wkt_parser::Projected_cs *p) override
	Initialize from parse tree. More...

Projection_type	projection_type () const override
	Get the map projection method. More...

bool	can_be_modified_to (const Spatial_reference_system &) 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::Projected_srs
	Projected_srs ()

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

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

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	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...

std::string	partial_proj4_parameters () const

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_latitude_of_origin
	Latitude chosen as origin of y-coordinates (EPSG 8801). More...

double	m_longitude_of_origin
	Longitude chosen as origin of x-coordinates (central meridian) (EPSG 8802). More...

double	m_scale_factor
	Multiplier for reducing a distance obtained from a map to the actual distance on the datum of the map (EPSG 8805). More...

double	m_false_easting
	Value added to x-coordinates (EPSG 8806). More...

double	m_false_northing
	Value added to y-coordinates (EPSG 8807). More...

Additional Inherited Members
Protected Member Functions inherited from gis::srs::Projected_srs
bool	common_proj_parameters_can_be_modified_to (const Spatial_reference_system &srs) const
	Checks if the parameters that are common to all projections can safely be modified to another SRS without causing computational differences. More...

Detailed Description

A Mercator (variant A) projection, alias Mercator (EPSG 9804).

Constructor & Destructor Documentation

◆ Mercator_variant_a_srs()

gis::srs::Mercator_variant_a_srs::Mercator_variant_a_srs ( )

inline

Member Function Documentation

◆ can_be_modified_to()

bool gis::srs::Mercator_variant_a_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::Mercator_variant_a_srs::clone ( )

inlineoverridevirtual

Clone the object.

Returns: A new Spatial_reference_system object

Implements gis::srs::Spatial_reference_system.

◆ init()

bool gis::srs::Mercator_variant_a_srs::init	(	gis::srid_t	srid,
		wkt_parser::Projected_cs *	p
	)

overridevirtual

Initialize from parse tree.

Parameters

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

Return values

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

Reimplemented from gis::srs::Projected_srs.

◆ proj4_parameters()

std::string gis::srs::Mercator_variant_a_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.

◆ projection_type()

Projection_type gis::srs::Mercator_variant_a_srs::projection_type ( ) const

inlineoverridevirtual

Get the map projection method.

Returns: Projection type

Implements gis::srs::Projected_srs.

Member Data Documentation

◆ m_false_easting

double gis::srs::Mercator_variant_a_srs::m_false_easting

private

Value added to x-coordinates (EPSG 8806).

◆ m_false_northing

double gis::srs::Mercator_variant_a_srs::m_false_northing

private

Value added to y-coordinates (EPSG 8807).

◆ m_latitude_of_origin

double gis::srs::Mercator_variant_a_srs::m_latitude_of_origin

private

Latitude chosen as origin of y-coordinates (EPSG 8801).

◆ m_longitude_of_origin

double gis::srs::Mercator_variant_a_srs::m_longitude_of_origin

private

Longitude chosen as origin of x-coordinates (central meridian) (EPSG 8802).

◆ m_scale_factor

double gis::srs::Mercator_variant_a_srs::m_scale_factor

private

Multiplier for reducing a distance obtained from a map to the actual distance on the datum of the map (EPSG 8805).

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

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Mercator_variant_a_srs()

Member Function Documentation

◆ can_be_modified_to()

◆ clone()

◆ init()

◆ proj4_parameters()

◆ projection_type()

Member Data Documentation

◆ m_false_easting

◆ m_false_northing

◆ m_latitude_of_origin

◆ m_longitude_of_origin

◆ m_scale_factor