org.opengis.cite.geomatics

Class Extents

java.lang.Object

org.opengis.cite.geomatics.Extents

public class Extents
extends Object

Provides utility methods to create or operate on envelope representations.

Method Summary

Methods

Modifier and Type	Method and Description
static Envelope	calculateEnvelope(NodeList geomNodes) Calculates the envelope that covers the given collection of GML geometry elements.
static Envelope	coalesceBoundingBoxes(List<Node> bboxNodes) Coalesces a sequence of bounding boxes so as to create an envelope that covers all of them.
static Envelope	createEnvelope(Node envelopeNode) Creates an Envelope from the given XML representation of a spatial extent (ows:BoundingBox, ows:WGS84BoundingBox, or gml:Envelope).
static Document	envelopeAsGML(Envelope envelope) Generates a standard GML representation (gml:Envelope) of an Envelope object.
static Polygon	envelopeAsPolygon(Envelope envelope) Creates a JTS Polygon having the same extent as the given envelope.
static String	envelopeToString(Envelope envelope) Returns a String representation of a bounding box suitable for use as a query parameter value (KVP syntax).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

calculateEnvelope

public static Envelope calculateEnvelope(NodeList geomNodes)
                                  throws JAXBException

Calculates the envelope that covers the given collection of GML geometry elements.

Parameters:

geomNodes - A NodeList containing GML geometry elements; it is assumed these all refer to the same CRS.

Returns:

An Envelope object representing the overall spatial extent (MBR) of the geometries.

Throws:

JAXBException - If a node cannot be unmarshalled to a geometry object.

envelopeAsGML

public static Document envelopeAsGML(Envelope envelope)

Generates a standard GML representation (gml:Envelope) of an Envelope object. Ordinates are rounded down to 2 decimal places.

Parameters:

envelope - An Envelope defining a bounding rectangle (or prism).

Returns:

A DOM Document with gml:Envelope as the document element.

envelopeAsPolygon

public static Polygon envelopeAsPolygon(Envelope envelope)

Creates a JTS Polygon having the same extent as the given envelope.

Parameters:

envelope - An Envelope defining a bounding rectangle.

Returns:

A Polygon with the relevant CoordinateReferenceSystem set as a user data object.

coalesceBoundingBoxes

public static Envelope coalesceBoundingBoxes(List<Node> bboxNodes)
                                      throws FactoryException,
                                             TransformException

Coalesces a sequence of bounding boxes so as to create an envelope that covers all of them. The resulting envelope will use the same CRS as the first bounding box in the list; the remaining bounding boxes will be transformed to this CRS if necessary.

Parameters:

bboxNodes - A list of elements representing common bounding boxes (ows:BoundingBox, ows:WGS84BoundingBox, or gml:Envelope).

Returns:

An Envelope encompassing the total extent of the given bounding boxes.

Throws:

FactoryException - If an unrecognized CRS reference is encountered or a corresponding CoordinateReferenceSystem cannot be constructed.

TransformException - If an attempt to perform a coordinate transformation fails for some reason.

createEnvelope

public static Envelope createEnvelope(Node envelopeNode)
                               throws FactoryException

Creates an Envelope from the given XML representation of a spatial extent (ows:BoundingBox, ows:WGS84BoundingBox, or gml:Envelope).

Parameters:

envelopeNode - A DOM Node (Document or Element) representing a spatial envelope.

Returns:

An envelope defining a spatial extent in some coordinate reference system.

Throws:

FactoryException - If an unrecognized CRS reference is encountered or a corresponding CoordinateReferenceSystem cannot be constructed for some reason.

envelopeToString

public static String envelopeToString(Envelope envelope)

Returns a String representation of a bounding box suitable for use as a query parameter value (KVP syntax). The value consists of a comma-separated sequence of data items as indicated below:

 LowerCorner coordinate 1
 LowerCorner coordinate 2
 LowerCorner coordinate N
 ...
 UpperCorner coordinate 1
 UpperCorner coordinate 2
 UpperCorner coordinate N
 crs URI (optional - default "urn:ogc:def:crs:OGC:1.3:CRS84")
 

Examples:

49.25,-123.1,50.0,-122.5,urn:ogc:def:crs:EPSG::4326

472944,5363287,516011,5456383,urn:ogc:def:crs:EPSG::32610

-123.1,49.25,-122.5,50.0

Note: The colon character (":") is allowed in the query component of a URI and thus does not need to be escaped. See RFC 3986, sec. 3.4.

Parameters:

envelope - An envelope specifying a geographic extent.

Returns:

A String suitable for use as a query parameter value (KVP syntax).

See Also:

OGC 06-121r9, 10.2.3