See: Description
Class | Description |
---|---|
LambertConicConformal |
Lambert Conic Conformal projection (EPSG codes 9801, 9802, 9803, 9826, 1051).
|
Mercator |
Mercator Cylindrical projection (EPSG codes 9804, 9805, 1026, 1024, 1044, 9841).
|
NormalizedProjection |
Base class for conversion services between ellipsoidal and cartographic projections.
|
PolarStereographic |
Polar Stereographic projection (EPSG codes 9810, 9829, 9830).
|
TransverseMercator |
Transverse Mercator projection (EPSG codes 9807).
|
Enum | Description |
---|---|
NormalizedProjection.ParameterRole |
Maps the parameters to be used for initializing
NormalizedProjection and its
normalization / denormalization matrices. |
Exception | Description |
---|---|
ProjectionException |
Thrown by
NormalizedProjection when a map projection failed. |
The best way to get a projection is to use the coordinate operation factory with the source and target CRS. That factory can bundle the projections defined in this package, together with any affine transform required for handling unit conversions and axis swapping, in a single (potentially concatenated) operation.
Users wanting to build their transforms directly should also avoid instantiating objects directly from this
package and use a math
transform factory instead.
The createParameterizedTransform(…)
method of that factory is subjects to the same rules than this package,
namely input coordinates must be (longitude, latitude) in decimal degrees
and output coordinates must be (easting, northing) in metres.
More on this convention is explained below.
Users wanting to know more about the available projections and their parameters should look at the list of coordinate operation methods. Only users interested in the implementation of those projections should look at this package.
However, map projections defined in this package are transform steps, not the full transform to the final CRS. All projections defined in this package must comply with the OGC 01-009 specification. This specification says (quoting section 10.6 at page 34):
Cartographic projection transforms are used by projected coordinate reference systems to map geographic coordinates (e.g. longitude and latitude) into (x, y) coordinates. These (x, y) coordinates can be imagined to lie on a plane, such as a paper map or a screen. All cartographic projection transforms will have the following properties:The Apache SIS implementation extends this rule to axis directions as well, i.e. (x, y) coordinates must be (East, North) oriented.Although all cartographic projection transforms must have the properties listed above, many projected coordinate reference systems have different properties. For example, in Europe some projected coordinate reference systems use grads instead of decimal degrees, and often the base geographic coordinate reference system is (latitude, longitude) instead of (longitude, latitude). This means that the cartographic projected transform is often used as a single step in a series of transforms, where the other steps change units and swap ordinates.
- Converts from (longitude, latitude) coordinates to (x,y).
- All angles are assumed to be decimal degrees, and all distances are assumed to be metres.
- The domain should be a subset of {[-180 … 180)×[-90 … 90]}°.
createBaseToDerived(…)
method defined in the MathTransformFactory
interface.
The same rule applies to the Krovak projection as well (at the opposite of what ESRI does).
NormalizedProjection
subclassIn other words, the transform method of the middle step works typically on longitude and latitude values in radians relative to the central meridian (not necessarily Greenwich). Its results are typically (x, y) coordinates having (East, North) axis orientation. However in some cases the actual input and output coordinates may be different than the above by some scale factor, translation or rotation, if the projection implementation choose to combine some linear coefficients with the above-cited normalization and denormalization affine transforms.
pj_fwd.c
and pj_inv.c
. This normalization makes the equations closer to the ones published in Snyder's book, where the
false easting, false northing and scale factor are usually not given.Defined in the sis-referencing
module
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