WebMercatorProjection
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new Cesium.WebMercatorProjection(ellipsoid)
engine/Source/Core/WebMercatorProjection.js 21

The map projection used by Google Maps, Bing Maps, and most of ArcGIS Online, EPSG:3857. This projection use longitude and latitude expressed with the WGS84 and transforms them to Mercator using the spherical (rather than ellipsoidal) equations.
参数名称 类型 默认值 描述信息
ellipsoid Ellipsoid Ellipsoid.WGS84 可选 The ellipsoid.
参考:

成员(属性)

static Cesium.WebMercatorProjection.MaximumLatitude : number
engine/Source/Core/WebMercatorProjection.js 88

The maximum latitude (both North and South) supported by a Web Mercator (EPSG:3857) projection. Technically, the Mercator projection is defined for any latitude up to (but not including) 90 degrees, but it makes sense to cut it off sooner because it grows exponentially with increasing latitude. The logic behind this particular cutoff value, which is the one used by Google Maps, Bing Maps, and Esri, is that it makes the projection square. That is, the rectangle is equal in the X and Y directions. The constant value is computed by calling: WebMercatorProjection.mercatorAngleToGeodeticLatitude(Math.PI)

readonly ellipsoid : Ellipsoid
engine/Source/Core/WebMercatorProjection.js 36

Gets the Ellipsoid.

方法

static Cesium.WebMercatorProjection.geodeticLatitudeToMercatorAngle(latitude) → number
engine/Source/Core/WebMercatorProjection.js 63

Converts a geodetic latitude in radians, in the range -PI/2 to PI/2, to a Mercator angle in the range -PI to PI.
参数名称 类型 描述信息
latitude number The geodetic latitude in radians.
返回值:
The Mercator angle.

static Cesium.WebMercatorProjection.mercatorAngleToGeodeticLatitude(mercatorAngle) → number
engine/Source/Core/WebMercatorProjection.js 50

Converts a Mercator angle, in the range -PI to PI, to a geodetic latitude in the range -PI/2 to PI/2.
参数名称 类型 描述信息
mercatorAngle number The angle to convert.
返回值:
The geodetic latitude in radians.

project(cartographic, result) → Cartesian3
engine/Source/Core/WebMercatorProjection.js 101

Converts geodetic ellipsoid coordinates, in radians, to the equivalent Web Mercator X, Y, Z coordinates expressed in meters and returned in a Cartesian3. The height is copied unmodified to the Z coordinate.
参数名称 类型 描述信息
cartographic Cartographic The cartographic coordinates in radians.
result Cartesian3 可选 The instance to which to copy the result, or undefined if a new instance should be created.
返回值:
The equivalent web mercator X, Y, Z coordinates, in meters.

unproject(cartesian, result) → Cartographic
engine/Source/Core/WebMercatorProjection.js 130

Converts Web Mercator X, Y coordinates, expressed in meters, to a Cartographic containing geodetic ellipsoid coordinates. The Z coordinate is copied unmodified to the height.
参数名称 类型 描述信息
cartesian Cartesian3 The web mercator Cartesian position to unrproject with height (z) in meters.
result Cartographic 可选 The instance to which to copy the result, or undefined if a new instance should be created.
返回值:
The equivalent cartographic coordinates.
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