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## org.deegree.model.coverage
Interface Coverage

All Known Subinterfaces:
  GridCoverage

All Known Implementing Classes:
  AbstractCoverage, AbstractGridCoverage, ByteGridCoverage, FloatGridCoverage, ImageGridCoverage, ShortGridCoverage

    public interface Coverage

Provides access to a coverage. The essential property of coverage is to be able to generate a value for any point within its domain. How coverage is represented internally is not a concern. For example consider the following different internal representations of coverage:

- A coverage may be represented by a set of polygons which exhaustively tile a plane (that is each point on the plane falls in precisely one polygon). The value returned by the coverage for a point is the value of an attribute of the polygon that contains the point.
- A coverage may be represented by a grid of values. The value returned by the coverage for a point is that of the grid value whose location is nearest the point.
- Coverage may be represented by a mathematical function. The value returned by the coverage for a point is just the return value of the function when supplied the coordinates of the point as arguments.
- Coverage may be represented by combination of these. For example, coverage may be represented by a combination of mathematical functions valid over a set of polynomials.

A coverage has a corresponding `SampleDimension` for each sample dimension in the coverage.
Implementation note:
We expect that many implementations of "org.opengis.coverage.grid.GridCoverage" will want to leverage the rich set of Java Advanced Imaging (JAI) features. For those implementations, it is recommended (but not required) to implement the `PropertySource` interface as well. In this case, implementation of `PropertySource` methods must be consistent with `getMetadataNames()` and `getMetadataValue(java.lang.String)` methods.

Version:
  Grid Coverage specification 1.0, $Revision: 20326 $, $Date: 2009-10-22 18:41:56 +0200 (Do, 22. Okt 2009) $
Author:
  OpenGIS® consortium, last edited by: $Author: mschneider $
See Also:
  `RenderableImage`, `ImageFunction`

Method Summary
`CoordinateSystem` | `getCoordinateReferenceSystem()` Specifies the coordinate reference system used when accessing a coverage or grid coverage with the `evaluate(...)`
`String[]` | `getDimensionNames()` The names of each dimension in the coverage.
`Envelope` | `getEnvelope()` The bounding box for the coverage domain in coordinate reference system coordinates.
`String[]` | `getMetadataNames()` List of metadata keywords for a coverage.
`String` | `getMetadataValue(String name)` Retrieve the metadata value for a given metadata name.
`int` | `getNumSampleDimensions()` The number of sample dimensions in the coverage.
`int` | `getNumSources()` Number of grid coverages which the grid coverage was derived from.
`RenderableImage` | `getRenderableImage(int xAxis, int yAxis)` Returns 2D view of this coverage as a renderable image.
`SampleDimension` | `getSampleDimension(int index)` Retrieve sample dimension information for the coverage.
`Coverage` | `getSource(int sourceDataIndex)` Returns the source data for a coverage.

Method Detail

### getCoordinateReferenceSystem

    CoordinateSystem getCoordinateReferenceSystem()

  Specifies the coordinate reference system used when accessing a coverage or grid coverage with the `evaluate(...)` methods. It is also the coordinate reference system of the coordinates used with the math transform This coordinate reference system is usually different than coordinate system of the grid. Grid coverage can be accessed (re-projected) with new coordinate reference system with the "org.opengis.coverage.processing.GridCoverageProcessor" component. In this case, a new instance of a grid coverage is created.
  Note: If a coverage does not have an associated coordinate reference system, the returned value will be `null`.

  Returns:
    The coordinate reference system used when accessing a coverage or grid coverage with the `evaluate(...)` methods, or `null`.

### getEnvelope

    Envelope getEnvelope()

  The bounding box for the coverage domain in coordinate reference system coordinates. For grid coverages, the grid cells are centered on each grid coordinate. The envelope for a 2-D grid coverage includes the following corner positions.

  >       (Minimum row - 0.5, Minimum column - 0.5) for the minimum coordinates
  >       (Maximum row - 0.5, Maximum column - 0.5) for the maximum coordinates

  If a grid coverage does not have any associated coordinate reference system, the minimum and maximum coordinate points for the envelope will be empty sequences.

  Returns:
    The bounding box for the coverage domain in coordinate system coordinates.

### getDimensionNames

    String[] getDimensionNames()

  The names of each dimension in the coverage. Typically these names are x, y, z and t. The number of items in the sequence is the number of dimensions in the coverage. Grid coverages are typically 2D (x, y) while other coverages may be 3D (x, y, z) or 4D (x, y, z, t). The number of dimensions of the coverage is the number of entries in the list of dimension names.

  Returns:
    The names of each dimension in the coverage.

### getNumSampleDimensions

    int getNumSampleDimensions()

  The number of sample dimensions in the coverage. For grid coverages, a sample dimension is a band.

  Returns:
    The number of sample dimensions in the coverage.

### getSampleDimension

    SampleDimension getSampleDimension(int index)
                                       throws IndexOutOfBoundsException

  Retrieve sample dimension information for the coverage. For a grid coverage a sample dimension is a band. The sample dimension information include such things as description, data type of the value (bit, byte, integer...), the no data values, minimum and maximum values and a color table if one is associated with the dimension. A coverage must have at least one sample dimension.

  Parameters:
    `index` - Index for sample dimension to retrieve. Indices are numbered 0 to ( n-1).
  Returns:
    Sample dimension information for the coverage.
  Throws:
    `IndexOutOfBoundsException` - if `index` is out of bounds.

### getNumSources

    int getNumSources()

  Number of grid coverages which the grid coverage was derived from. This implementation specification does not include interfaces for creating collections of coverages therefore this value will usually be one indicating an adapted grid coverage, or zero indicating a raw grid coverage.

  Returns:
    The number of grid coverages which the grid coverage was derived from.

### getSource

    Coverage getSource(int sourceDataIndex)
                       throws IndexOutOfBoundsException

  Returns the source data for a coverage. This is intended to allow applications to establish what `Coverage`s will be affected when others are updated, as well as to trace back to the "raw data".

  Parameters:
    `sourceDataIndex` - Source coverage index. Indexes start at 0.
  Returns:
    The source data for a coverage.
  Throws:
    `IndexOutOfBoundsException` - if `sourceDataIndex` is out of bounds.
  See Also:
    `getNumSources()`, "org.opengis.coverage.grid.GridCoverage#getSource"

### getMetadataNames

    String[] getMetadataNames()

  List of metadata keywords for a coverage. If no metadata is available, the sequence will be empty.

  Returns:
    the list of metadata keywords for a coverage.
  See Also:
    `getMetadataValue(java.lang.String)`, `PropertySource.getPropertyNames()`

### getMetadataValue

    String getMetadataValue(String name)
                            throws MetadataNameNotFoundException

  Retrieve the metadata value for a given metadata name.

  Parameters:
    `name` - Metadata keyword for which to retrieve data.
  Returns:
    the metadata value for a given metadata name.
  Throws:
    `MetadataNameNotFoundException` - if there is no value for the specified metadata name.
  See Also:
    `getMetadataNames()`, `PropertySource.getProperty(java.lang.String)`

### getRenderableImage

    RenderableImage getRenderableImage(int xAxis,
                                       int yAxis)
                                       throws UnsupportedOperationException,
                                              IndexOutOfBoundsException

  Returns 2D view of this coverage as a renderable image. This optional operation allows interoperability with Java2D. If this coverage is a "org.opengis.coverage.grid.GridCoverage" backed by a `RenderedImage`, the underlying image can be obtained with: `getRenderableImage(0,1).createDefaultRendering()`

  Parameters:
    `xAxis` - Dimension to use for the x axis.
    `yAxis` - Dimension to use for the y axis.
  Returns:
    A 2D view of this coverage as a renderable image.
  Throws:
    `UnsupportedOperationException` - if this optional operation is not supported.
    `IndexOutOfBoundsException` - if `xAxis` or `yAxis` is out of bounds.

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