Java Doc for CoverageStack.java in  » GIS » GeoTools-2.4.1 » org » geotools » coverage » Java Source Code / Java DocumentationJava Source Code and Java Documentation

Each in the stack usually covers the same , but this is not a requirement. However, they must use the same . For performance reason, the later condition will not be checked except at construction time if the CRS is provided in the envelope, and at evaluation time if Java assertion are enabled. If the CRS of coverage elements is uncertain, consider wrapping them in a TransformedCoverage object.

Coverage elements are often two-dimensional, but this is not a requirement. This stack will simply append one more dimension to the coverage element's CRS dimensions. Coverage elements may be other CoverateStack objects, thus allowing construction of coverages with four or more dimensions.

GridCoverage2D objects tend to be big. In order to keep memory usage raisonable, this implementation doesn't requires all GridCoverage objects at once. Instead, it requires an array of Element objects, which will load the coverage content only when first needed. This CoverageStack implementation remember the last coverage elements used; it will not trig new data loading as long as consecutive calls to evaluate(...) methods require the same coverage elements. Apart from this very simple caching mechanism, caching is the responsability of Element implementations. Note that this simple caching mechanism is suffisient if evaluate(...) methods are invoked with increasing z values.

Each coverage element is expected to extends over a range of z values (the new dimensions appended by this CoverageStack ). If an evaluate(...) method is invoked with a z value not falling in the middle of a coverage element, a linear interpolation is applied.

Note: This implementation is thread-safe.
since:
   2.1
version:
   $Id: CoverageStack.java 27862 2007-11-12 19:51:19Z desruisseaux $
author:
   Martin Desruisseaux

 GridCoverageFactory     factory = ...;
 CoordinateReferenceSystem crs2D = ...;  // Yours horizontal CRS.
 TemporalCRS             timeCRS = ...;  // Yours CRS for time measurement.
 CoordinateReferenceSystem crs3D = new CompoundCRS(crs3D, timeCRS);
 List<Coverage> coverages = new ArrayList<Coverage>();
 GeneralEnvelope envelope = new GeneralEnvelope(3); // A 3-dimensional envelope.
 envelope.setRange(...);                            // Set the horizontal part.
 for (int i=0; i<...; i++) {
 envelope.setRange(2, startTime, endTime);
 coverages.add(factory.create(..., crs, envelope, ...);
 }
 

• If there is no coverage available for the specified z value, returns an .
• If there is only one coverage available, or if the specified z value falls exactly in the middle of the (i.e. no interpolation are needed), or if , then this method returns a .
• Otherwise, this method returns a list containing at least 2 coverages, one before and one after the specified z value.