Enum WraparoundMethod
 All Implemented Interfaces:
Serializable
,Comparable<WraparoundMethod>
,Constable
GeneralEnvelope
documentation.
When such regions are used with libraries or algorithms that are not designed for handling wraparound axes,
it may be necessary to convert those regions to simpler geometric representations that algorithm can handle.
The CONTIGUOUS
, CONTIGUOUS_LOWER
, CONTIGUOUS_UPPER
and EXPAND
enumeration
values are strategies for simplifying the problem at the cost of shifting geometries partially outside the
coordinate system domain, or making geometry bigger than necessary.
Alternatives
All methods in this enumeration change the envelope or geometry without changing the coordinate system. Another approach for solving the antimeridian problem is to change the range of longitude values, for example using [0 … 360]° instead of [−180 … +180]°, and then normalize envelopes in that new range. But this approach is interesting only when all geometries are known to fit in the new range of longitude values, otherwise this approach is only moving the problem to another part of the world.Generalization
The documentation in this class talks about longitude values crossing the antimeridian because it is the most common case. But Apache SIS actually handles wraparound axes in a generic way. The same discussion applies also for example to the temporal axis of climatological data (January averages, February averages, …, December averages then back to January). Since:
 1.1
 See Also:
Defined in the sisreferencing
module

Nested Class Summary
Nested classes/interfaces inherited from class Enum
Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary
Enum ConstantDescriptionMake geometries contiguous by possibly shifting any corner outside the coordinate system domain.Make geometries contiguous by possibly shifting lower corner outside the coordinate system domain.Make geometries contiguous by possibly shifting upper corner outside the coordinate system domain.Possibly expand the envelope to include the whole area in a single envelope or geometry.No check performed for wraparound axes.Envelope represented in a way where "lower" value may be greater than "upper" value.Possibly separate the envelope in as many simple envelopes or geometries as needed. 
Method Summary
Modifier and TypeMethodDescriptionstatic WraparoundMethod
Returns the enum constant of this type with the specified name.static WraparoundMethod[]
values()
Returns an array containing the constants of this enum type, in the order they are declared.Methods inherited from class Enum
clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Enum Constant Details

NONE
No check performed for wraparound axes. If a normalized envelope crosses the antimeridian (lower longitude value > upper value), then a polygon created from the 4 envelope corners would define a different area than the envelope: the "interior" and "exterior" of the geometry would be interchanged. Use this method only when knowing that the envelopes or geometries do not cross the antimeridian.Example: given the
BBOX(+170 0, 170 1)
envelope, a polygon created from the 4 corners and ignoring the fact that the envelope crosses the antimeridian may be as below:POLYGON(+170 0, 170 0, 170 1, +170 1, +170 0)

NORMALIZE
Envelope represented in a way where "lower" value may be greater than "upper" value. This method can represent envelopes crossing the antimeridian without the sacrifices imposed by other methods (moving a corner outside the coordinate system domain or expanding the envelope). However this method can be used only with algorithms designed for handling this representation. This is the case of Apache SISGeneralEnvelope
but often not the case of geometry libraries.This method is said "normalized" because it is the only representation in Apache SIS which is guaranteed to produce consistent results when adding points to an envelope or when computing unions and intersections of envelopes. All other methods may produce unpredictable or suboptimal results, depending for example whether two geometries have been made contiguous on the same side of the coordinate system domain (
CONTIGUOUS_LOWER
versusCONTIGUOUS_UPPER
). See Also:

CONTIGUOUS_UPPER
Make geometries contiguous by possibly shifting upper corner outside the coordinate system domain. If a normalized envelope crosses the antimeridian (upper longitude value < lower value), then an integer amount of cycles (360°) will be added to the upper longitude value until we getupper > lower
. This will usually result in an upper corner value outside the [−180 … +180]° longitude range.Example: given the
BBOX(+170 0, 170 1)
envelope, a polygon created after shifting the "upper" corner (170 1) may be as below:POLYGON(+170 0, +190 0, +190 1, +170 1, +170 0)

CONTIGUOUS_LOWER
Make geometries contiguous by possibly shifting lower corner outside the coordinate system domain. If a normalized envelope crosses the antimeridian (lower longitude value > upper value), then an integer amount of cycles (360°) will be subtracted from the lower longitude value until we getlower < upper
. This will usually result in a lower corner value outside the [−180 … +180]° longitude range.Example: given the
BBOX(+170 0, 170 1)
envelope, a polygon created after shifting the "lower" corner (+170 0) may be as below:POLYGON(190 0, 170 0, 170 1, 190 1, 190 0)

CONTIGUOUS
Make geometries contiguous by possibly shifting any corner outside the coordinate system domain. This method is equivalent to eitherCONTIGUOUS_LOWER
orCONTIGUOUS_UPPER
, depending which method minimizes the area outside the coordinate system domain. 
EXPAND
Possibly expand the envelope to include the whole area in a single envelope or geometry. If a normalized envelope crosses the antimeridian (lower corner values > upper corner values), then the envelope is expanded to span an area from axis minimum value to axis maximum value. This ensures that the geometry contains the original envelope area but is wider. Compared to theCONTIGUOUS
methods, thisEXPAND
method does not move any parts outside the coordinate system domain.Example: given the
BBOX(+170 0, 170 1)
envelope, a polygon created after expanding the envelope may be as below:POLYGON(180 0, +180 0, +180 1, 180 1, 180 0)
 See Also:

SPLIT
Possibly separate the envelope in as many simple envelopes or geometries as needed. If a normalized envelope crosses the antimeridian (lower corner values > upper corner values), then a geometry created from this envelope will be composed of 2 or more polygons on each side of the coordinate system. This ensures that the geometries represent exactly the envelope interior but with more complexity.Example: given the
BBOX(+170 0, 170 1)
envelope, polygons created after splitting the envelope may be as below:MULTIPOLYGON( (180 0, 170 0, 170 1, 180 1, 180 0) (+170 0, +180 0, +180 1, +170 1, +170 0))
 See Also:


Method Details

values
Returns an array containing the constants of this enum type, in the order they are declared. Returns:
 an array containing the constants of this enum type, in the order they are declared

valueOf
Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.) Parameters:
name
 the name of the enum constant to be returned. Returns:
 the enum constant with the specified name
 Throws:
IllegalArgumentException
 if this enum type has no constant with the specified nameNullPointerException
 if the argument is null
