Package org.opengis.coverage.grid

Grid coverages (coverages with gridded data).

See:
Description

Interface Summary

GridCoverage	Represent the basic implementation which provides access to grid coverage data.
GridGeometry	Describes the geometry and georeferencing information of the grid coverage.
GridPacking	Describes the packing of data values within grid coverages.
GridRange	Specifies the range of valid coordinates for each dimension of the coverage.

Class Summary

ByteInValuePacking	Specifies the order of the bytes in multi-byte values.
ValueInBytePacking	Order of values packed in a byte for sample dimensions with less than 8 bits.

Exception Summary

CannotCreateGridCoverageException	Thrown when a grid coverage can't be created.
GridNotEditableException	Thrown when an attempt is made to write in a non-editable grid.
InvalidRangeException	Thrown when a grid range is out of grid coverage bounds.

Package org.opengis.coverage.grid Description

Grid coverages (coverages with gridded data). The following is adapted from OpenGIS® Grid Coverages Implementation Specification.

This Grid Coverage Implementation specification can accommodate grid coverages with the following characteristics:

• Variable number of bits per grid value (bits per pixel): 1, 2, 4 unsigned integer; 8, 16, 32 signed and unsigned integer; 32, 64 real numbers.
• 1 to N number of bands.
• 1 to N dimensions.
• For grids with multiple bands, band values can be ordered by dimension. For example, a 2D grid coverage can be ordered row, column, band (pixel interleaved), row, band, column (line interleaved) or band, row, column (band sequential).
• Support for a variable number of "no data values".
• Various color models: Gray Scale, pseudo color (any size), RGB, CMYK and HSL.
• Support of overviews or pyramids (reduced resolution data sets).

Grid Coordinate System

A grid coverage has a grid coordinate reference system which allows for addressing individual cells in the grid. Individual cells are centered on the grid points. A grid has an ordering of cell values with the first cell in this ordering having a grid coordinate of 0,0. A two dimensional grid coverage with 512 rows and 512 columns would have grid coordinates with a range from 0 to 511 rows and 0 to 511 columns. The gridRange attribute GridGeometry structure defines the grid coordinate range. The number of cells in a dimension of the grid can be calculated as grid range maximum – minimum.

Grid Coverage Tiling

This implementation specification has no explicit interfaces to retrieve data values from a grid coverage in tiles. It is expected that the implementation will efficiently retrieve data values when the client implementation retrieves data values on tile boundaries. The optimal size to access a dimension can be determined from the optimalDataBlockSizes attribute.

Interoperability

To help interoperability, many interfaces contained in this architecture have been made immutable. The assumption is that the objects supporting these interfaces should be immutable. This means that the objects should not change after a factory has created them. In particular, the following interfaces are assumed to be backed by immutable objects: SampleDimension, org.opengis.coverage.grid.Format, org.opengis.coverage.grid.GridCoverageExchange, Operation, org.opengis.coverage.processing.GridAnalysis, GridCoverageProcessor.

In a GridCoverage, only the cell values may change. The size, geometry, interpolation, sequencing etc should never change. However, clients should be aware that the Grid Coverage object behind the GridCoverage interface may be adapted from other GridCoverage interfaces, so changing the grid point (pixel) values through one GridCoverage could change the grid point values in others. To allow client applications to anticipate adapted Grid Coverages being changed indirectly, the source Grid Geometry object(s) for adapted Grid Geometry objects can be traced.