Classes for geospatial computations in Cesium. More...

Classes
class	BoundingRegion
	A bounding volume specified as a longitude/latitude bounding box and a minimum and maximum height. More...

class	BoundingRegionBuilder

class	BoundingRegionWithLooseFittingHeights
	A BoundingRegion whose heights might be very inaccurate and so distances should be estimated conservatively for level-of-detail computations. More...

class	Cartographic
	A position defined by longitude, latitude, and height. More...

class	CartographicPolygon
	A 2D polygon expressed as a list of longitude/latitude coordinates in radians. More...

class	EarthGravitationalModel1996Grid
	Loads and queries heights from an Earth Gravitational Model 1996 (EGM96) grid. More...

class	Ellipsoid
	A quadratic surface defined in Cartesian coordinates. More...

class	EllipsoidTangentPlane
	A plane tangent to an Ellipsoid at a certain origin position. More...

class	GeographicProjection
	A map projection where longitude and latitude are mapped using an Ellipsoid. More...

class	GlobeAnchor
	Anchors an object to the globe by defining a transformation from the object's coordinate to the globe-fixed coordinate system (usually Earth-Centered, Earth-Fixed or ECEF). More...

class	GlobeRectangle
	A two-dimensional, rectangular region on a globe, specified using longitude and latitude coordinates. The region is rectangular in terms of longitude-latitude coordinates, but may be far from rectangular on the actual globe surface. More...

class	GlobeTransforms
	Transforms between globe-related coordinate systems. More...

class	LocalHorizontalCoordinateSystem
	A coordinate system created from a local horizontal plane at a particular origin point on the globe. More...

class	S2CellBoundingVolume

class	S2CellID
	A 64-bit unsigned integer that uniquely identifies a cell in the S2 cell decomposition. More...

class	SimplePlanarEllipsoidCurve
	Produces points on an ellipse that lies on a plane that intersects the center of the earth and each of the input coordinates. The height above the surface at each point along the curve will be a linear interpolation between the source and destination heights. More...

class	WebMercatorProjection
	The map projection used by Google Maps, Bing Maps, and most of ArcGIS Online, EPSG:3857. More...

Typedefs
typedef std::variant< GeographicProjection, WebMercatorProjection >	Projection
	A projection. More...

Enumerations
enum class	LocalDirection { East , North , West , South , Up , Down }

Functions
double	calcQuadtreeMaxGeometricError (const CesiumGeospatial::Ellipsoid &ellipsoid) noexcept
	Computes the maximum geometric error per radian of a quadtree with certain assumptions. More...

glm::dvec3	projectPosition (const Projection &projection, const Cartographic &position)
	Projects a position on the globe using the given Projection. More...

Cartographic	unprojectPosition (const Projection &projection, const glm::dvec3 &position)
	Unprojects a position from the globe using the given Projection. More...

CesiumGeometry::Rectangle	projectRectangleSimple (const Projection &projection, const GlobeRectangle &rectangle)
	Projects a rectangle on the globe by simply projecting its four corners. More...

GlobeRectangle	unprojectRectangleSimple (const Projection &projection, const CesiumGeometry::Rectangle &rectangle)
	Unprojects a rectangle to the globe by simply unprojecting its four corners. More...

CesiumGeometry::AxisAlignedBox	projectRegionSimple (const Projection &projection, const BoundingRegion &region)
	Projects a bounding region on the globe by simply projecting its eight corners. More...

BoundingRegion	unprojectRegionSimple (const Projection &projection, const CesiumGeometry::AxisAlignedBox &box, const CesiumGeospatial::Ellipsoid &ellipsoid CESIUM_DEFAULT_ELLIPSOID)
	Unprojects a box to the globe by simply unprojecting its eight corners. More...

glm::dvec2	computeProjectedRectangleSize (const Projection &projection, const CesiumGeometry::Rectangle &rectangle, double maxHeight, const Ellipsoid &ellipsoid CESIUM_DEFAULT_ELLIPSOID)
	Computes the approximate real-world size, in meters, of a given projected rectangle. More...

const Ellipsoid &	getProjectionEllipsoid (const Projection &projection)
	Obtains the ellipsoid used by a Projection variant.

Detailed Description

Classes for geospatial computations in Cesium.

Typedef Documentation

◆ Projection

typedef std::variant<GeographicProjection, WebMercatorProjection> CesiumGeospatial::Projection

A projection.

This is a std::variant of different types of map projections that can convert between projected map coordinates and Cartographic coordinates.

See also: GeographicProjection; WebMercatorProjection

Definition at line 25 of file Projection.h.

Function Documentation

◆ calcQuadtreeMaxGeometricError()

double CesiumGeospatial::calcQuadtreeMaxGeometricError ( const CesiumGeospatial::Ellipsoid & ellipsoid )

noexcept

Computes the maximum geometric error per radian of a quadtree with certain assumptions.

The geometric error for a tile can be computed by multiplying the value returned by this function by the width of the tile in radians.

This function computes a suitable geometric error for a 65x65 terrain heightmap where the vertical error is 25% of the horizontal spacing between height samples at the equator.

Parameters

ellipsoid The ellipsoid.

Returns: The max geometric error.

◆ computeProjectedRectangleSize()

glm::dvec2 CesiumGeospatial::computeProjectedRectangleSize	(	const Projection &	projection,
		const CesiumGeometry::Rectangle &	rectangle,
		double	maxHeight,
		const Ellipsoid &ellipsoid	CESIUM_DEFAULT_ELLIPSOID
	)

Computes the approximate real-world size, in meters, of a given projected rectangle.

The returned X component corresponds to the size in the projected X direction, while the returned Y component corresponds to the size in the projected Y direction.

Parameters

projection	The projection.
rectangle	The projected rectangle to measure.
maxHeight	The maximum height of the geometry inside the rectangle.
ellipsoid	The ellipsoid used to convert longitude and latitude to ellipsoid-centered coordinates.

Returns: The approximate size.

◆ projectPosition()

glm::dvec3 CesiumGeospatial::projectPosition	(	const Projection &	projection,
		const Cartographic &	position
	)

Projects a position on the globe using the given Projection.

Parameters

projection	The projection.
position	The Cartographic position.

Returns: The coordinates of the projected point, in the coordinate system of the given projection.

◆ projectRectangleSimple()

CesiumGeometry::Rectangle CesiumGeospatial::projectRectangleSimple	(	const Projection &	projection,
		const GlobeRectangle &	rectangle
	)

Projects a rectangle on the globe by simply projecting its four corners.

This is only accurate when the globe rectangle is still a rectangle after projecting, which is true for WebMercatorProjection but not necessarily true for other projections.

Parameters

projection	The projection.
rectangle	The globe rectangle to be projected.

Returns: The projected rectangle.

◆ projectRegionSimple()

CesiumGeometry::AxisAlignedBox CesiumGeospatial::projectRegionSimple	(	const Projection &	projection,
		const BoundingRegion &	region
	)

Projects a bounding region on the globe by simply projecting its eight corners.

This is only accurate when the globe box is still a box after projecting, which is true for WebMercatorProjection but not necessarily true for other projections.

Parameters

projection	The projection.
boundingRegion	The bounding region to be projected.

Returns: The projected box.

◆ unprojectPosition()

Cartographic CesiumGeospatial::unprojectPosition	(	const Projection &	projection,
		const glm::dvec3 &	position
	)

Unprojects a position from the globe using the given Projection.

Parameters

projection	The projection.
position	The coordinates of the point, in meters.

Returns: The Cartographic position.

◆ unprojectRectangleSimple()

GlobeRectangle CesiumGeospatial::unprojectRectangleSimple	(	const Projection &	projection,
		const CesiumGeometry::Rectangle &	rectangle
	)

Unprojects a rectangle to the globe by simply unprojecting its four corners.

This is only accurate when the rectangle is still a rectangle after unprojecting, which is true for WebMercatorProjection but not necessarily true for other projections.

Parameters

projection	The projection.
rectangle	The rectangle to be unprojected.

Returns: The unprojected rectangle.

◆ unprojectRegionSimple()

BoundingRegion CesiumGeospatial::unprojectRegionSimple	(	const Projection &	projection,
		const CesiumGeometry::AxisAlignedBox &	box,
		const CesiumGeospatial::Ellipsoid &ellipsoid	CESIUM_DEFAULT_ELLIPSOID
	)

Unprojects a box to the globe by simply unprojecting its eight corners.

This is only accurate when the box is still a box after unprojecting, which is true for WebMercatorProjection but not necessarily true for other projections.

Parameters

projection	The projection.
box	The box to be unprojected.

Returns: The unprojected bounding region.

Classes

Typedefs

Enumerations

Functions

Detailed Description

Typedef Documentation

◆ Projection

Function Documentation

◆ calcQuadtreeMaxGeometricError()

◆ computeProjectedRectangleSize()

◆ projectPosition()

◆ projectRectangleSimple()

◆ projectRegionSimple()

◆ unprojectPosition()

◆ unprojectRectangleSimple()

◆ unprojectRegionSimple()