Class Envelopes
Envelope transformations
Alltransform(…)
methods in this class take in account the curvature of the transformed shape.
For example the shape of a geographic envelope (figure below on the left side) is not rectangular in a
conic projection (figure below on the right side). In order to get the envelope represented by the red
rectangle, projecting the four corners of the geographic envelope is not sufficient since we would miss
the southerner part.
Envelope before map projection  Shape of the projected envelope 

MathTransform
implementations involved in the
operation (directly or indirectly) support derivative,
for more accurate calculation of curve extremum. This is the case of most Apache SIS implementations.
The transform(…)
methods in this class expect an arbitrary Envelope
with one
of the following arguments: MathTransform
, CoordinateOperation
or CoordinateReferenceSystem
.
The recommended method is the one expecting a CoordinateOperation
object,
since it contains sufficient information for handling the cases of envelopes that encompass a pole.
The method expecting a CoordinateReferenceSystem
object is merely a convenience method that
infers the coordinate operation itself, but at the cost of performance if the same operation needs
to be applied on many envelopes.

Method Summary
Modifier and TypeMethodDescriptionstatic Envelope
Puts together a list of envelopes, each of them using an independent coordinate reference system.static CoordinateOperation
findOperation
(Envelope source, Envelope target) Finds a mathematical operation from the CRS of the given source envelope to the CRS of the given target envelope.static Envelope
fromWKT
(CharSequence wkt) Returns the bounding box of a geometry defined in Well Known Text (WKT) format.static GeneralEnvelope
Computes the intersection of all given envelopes, transforming them to a common CRS if necessary.static String
toPolygonWKT
(Envelope envelope) Formats the given envelope as aPOLYGON
element in the Well Known Text (WKT) format.static String
Formats the given envelope as aBOX
element.toTimeRange
(Envelope envelope) Returns the time range of the first dimension associated to a temporal CRS.static Envelope
transform
(Envelope envelope, CoordinateReferenceSystem targetCRS) Transforms the given envelope to the specified CRS.static GeneralEnvelope
transform
(CoordinateOperation operation, Envelope envelope) Transforms an envelope using the given coordinate operation.static GeneralEnvelope
transform
(MathTransform transform, Envelope envelope) Transforms an envelope using the given math transform.static GeneralEnvelope
Computes the union of all given envelopes, transforming them to a common CRS if necessary.

Method Details

compound
Puts together a list of envelopes, each of them using an independent coordinate reference system. The dimension of the returned envelope is the sum of the dimension of all components. If all components have a coordinate reference system, then the returned envelope will have a compound coordinate reference system. Parameters:
components
 the envelopes to aggregate in a single envelope, in the given order. Returns:
 the aggregation of all given envelopes.
 Throws:
FactoryException
 if the geodetic factory failed to create the compound CRS. Since:
 1.0
 See Also:

union
Computes the union of all given envelopes, transforming them to a common CRS if necessary. If all envelopes use the same CRS (ignoring metadata
) or if the CRS of all envelopes isnull
, then the union is computed without transforming any envelope. Otherwise all envelopes are transformed to a common CRS before union is computed. The CRS of the returned envelope may different than the CRS of all given envelopes. Parameters:
envelopes
 the envelopes for which to compute union. Null elements are ignored. Returns:
 union of given envelopes, or
null
if the given array does not contain nonnull elements.  Throws:
TransformException
 if this method can not determine a common CRS, or if a transformation failed. Since:
 1.0
 See Also:

intersect
Computes the intersection of all given envelopes, transforming them to a common CRS if necessary. If all envelopes use the same CRS (ignoring metadata
) or if the CRS of all envelopes isnull
, then the intersection is computed without transforming any envelope. Otherwise all envelopes are transformed to a common CRS before intersection is computed. The CRS of the returned envelope may different than the CRS of all given envelopes. Parameters:
envelopes
 the envelopes for which to compute intersection. Null elements are ignored. Returns:
 intersection of given envelopes, or
null
if the given array does not contain nonnull elements.  Throws:
TransformException
 if this method can not determine a common CRS, or if a transformation failed. Since:
 1.0
 See Also:

findOperation
public static CoordinateOperation findOperation(Envelope source, Envelope target) throws FactoryException Finds a mathematical operation from the CRS of the given source envelope to the CRS of the given target envelope. For nonnull georeferenced envelopes, this method is equivalent to the following code withareaOfInterest
computed as the union of the two envelopes:
If at least one envelope is null or has no CRS, then this method returnsreturn CRS.findOperation(CoordinateReferenceSystem, CoordinateReferenceSystem, GeographicBoundingBox) CRS.findOperation(source.getCoordinateReferenceSystem(), target.getCoordinateReferenceSystem(), areaOfInterest)
null
. Parameters:
source
 the source envelope, ornull
.target
 the target envelope, ornull
. Returns:
 the mathematical operation from
source
CRS totarget
CRS, ornull
if at least one argument is null or has no CRS.  Throws:
OperationNotFoundException
 if no operation was found between the given pair of CRS.FactoryException
 if the operation can not be created for another reason. Since:
 1.0
 See Also:

transform
public static Envelope transform(Envelope envelope, CoordinateReferenceSystem targetCRS) throws TransformException Transforms the given envelope to the specified CRS. If any argument is null, or if the envelope CRS is null or the same instance than the given target CRS, then the given envelope is returned unchanged. Otherwise a new transformed envelope is returned.Performance tip
If there is many envelopes to transform with the same source and target CRS, then it is more efficient to get theCoordinateOperation
orMathTransform
instance once and invoke one of the otherstransform(…)
methods. Parameters:
envelope
 the envelope to transform (may benull
).targetCRS
 the target CRS (may benull
). Returns:
 a new transformed envelope, or directly
envelope
if no change was required.  Throws:
TransformException
 if a transformation was required and failed. Since:
 0.5

transform
public static GeneralEnvelope transform(MathTransform transform, Envelope envelope) throws TransformException Transforms an envelope using the given math transform. The transformation is only approximated: the returned envelope may be bigger than necessary, or smaller than required if the bounding box contains a pole. The coordinate reference system of the returned envelope will be null.Limitation
This method can not handle the case where the envelope contains the North or South pole, or when it crosses the ±180° longitude, becauseMathTransform
does not carry sufficient information. For a more robust envelope transformation, usetransform(CoordinateOperation, Envelope)
instead. Parameters:
transform
 the transform to use.envelope
 envelope to transform, ornull
. This envelope will not be modified. Returns:
 the transformed envelope, or
null
ifenvelope
was null.  Throws:
TransformException
 if a transform failed. Since:
 0.5
 See Also:

transform
public static GeneralEnvelope transform(CoordinateOperation operation, Envelope envelope) throws TransformException Transforms an envelope using the given coordinate operation. The transformation is only approximated: the returned envelope may be bigger than the smallest possible bounding box, but should not be smaller in most cases.This method can handle the case where the envelope contains the North or South pole, or when it cross the ±180° longitude.
Note: If the envelope CRS is nonnull, then the caller should ensure that the operation source CRS is the same than the envelope CRS. In case of mismatch, this method transforms the envelope to the operation source CRS before to apply the operation. This extra step may cause a lost of accuracy. In order to prevent this method from performing such pretransformation (if not desired), callers can ensure that the envelope CRS isnull
before to call this method. Parameters:
operation
 the operation to use.envelope
 envelope to transform, ornull
. This envelope will not be modified. Returns:
 the transformed envelope, or
null
ifenvelope
was null.  Throws:
TransformException
 if a transform failed. Since:
 0.5
 See Also:

fromWKT
Returns the bounding box of a geometry defined in Well Known Text (WKT) format. This method does not check the consistency of the provided WKT. For example it does not check that every points in aLINESTRING
have the same dimension. However this method ensures that the parenthesis are balanced, in order to catch some malformed WKT.Examples:SeeBOX(180 90, 180 90)
(not really a geometry, but understood by many software products)POINT(6 10)
MULTIPOLYGON(((1 1, 5 1, 1 5, 1 1),(2 2, 3 2, 3 3, 2 2)))
GEOMETRYCOLLECTION(POINT(4 6),LINESTRING(3 8,7 10))
GeneralEnvelope(CharSequence)
for more information about the parsing rules. Parameters:
wkt
 theBOX
,POLYGON
or other kind of element to parse. Returns:
 the envelope of the given geometry.
 Throws:
FactoryException
 if the given WKT can not be parsed. See Also:

toString
Formats the given envelope as aBOX
element. The output is like below, where n is the number of dimensions (omitted if equals to 2):BOX
nD(
lower corner,
upper corner)
Note: TheThe string returned by this method can be parsed by theBOX
element is not part of the standard Well Known Text (WKT) format. However it is understood by many software libraries, for example GDAL and PostGIS.GeneralEnvelope
constructor. Parameters:
envelope
 the envelope to format. Returns:
 this envelope as a
BOX
orBOX3D
(most typical dimensions) element.  See Also:

toPolygonWKT
Formats the given envelope as aPOLYGON
element in the Well Known Text (WKT) format.POLYGON
can be used as an alternative toBOX
when the element needs to be considered as a standard WKT geometry.The string returned by this method can be parsed by the
GeneralEnvelope
constructor. Parameters:
envelope
 the envelope to format. Returns:
 the envelope as a
POLYGON
in WKT format.  Throws:
IllegalArgumentException
 if the given envelope can not be formatted. See Also:

toTimeRange
Returns the time range of the first dimension associated to a temporal CRS. This convenience method converts floating point values to instants usingDefaultTemporalCRS.toInstant(double)
. Parameters:
envelope
 envelope from which to extract time range, ornull
if none. Returns:
 time range in the given envelope.
 Since:
 1.1
 See Also:
