2.2 SDO_RASTER Object Type and the Raster Data Table
In the GeoRaster object-relational model, a raster data table (RDT) is used to store all cell data in a raster image.
The cell data of a GeoRaster object is blocked, and each block is stored in the RDT
as one row. You specify this table in the rasterDataTable
attribute of the
SDO_GEORASTER object, as explained in rasterDataTable
Attribute. You must create the RDT before you store any cell data in it.
The RDT is an object table, defined as a table of SDO_RASTER object type or as a relational table that includes all columns defined by object type SDO_RASTER. The RDT name must be unique in the database, as described in Raster Data Table.
The SDO_RASTER object type is defined as:
CREATE TYPE sdo_raster AS OBJECT ( rasterID NUMBER, pyramidLevel NUMBER, bandBlockNumber NUMBER, rowBlockNumber NUMBER, columnBlockNumber NUMBER, blockMBR SDO_GEOMETRY, rasterBlock BLOB);
The sections that follow describe the semantics of each SDO_RASTER attribute.
- rasterID Attribute
- pyramidLevel Attribute
- bandBlockNumber Attribute
- rowBlockNumber Attribute
- columnBlockNumber Attribute
- blockMBR Attribute
- rasterBlock Attribute
Parent topic: GeoRaster Data Types and Related Structures
2.2.1 rasterID Attribute
The rasterID
attribute in the SDO_RASTER object must be a number that matches the rasterID
value in its associated SDO_GEORASTER object. (The rasterID
attribute of the SDO_GEORASTER object is described in rasterID Attribute.) The matching of these numbers identifies the raster block as belonging to a specific GeoRaster object.
Parent topic: SDO_RASTER Object Type and the Raster Data Table
2.2.2 pyramidLevel Attribute
The pyramidLevel
attribute identifies the pyramid level for this block of cells. The pyramid level is 0 or any positive integer. Pyramid levels are used to create reduced resolution images that require less storage space. A pyramid level of 0 indicates the original raster data; that is, there is no reduction in the image resolution and no change in the storage space required. Values greater than 0 (zero) indicate increasingly reduced levels of image resolution and reduced storage space requirements. For more information about pyramids, see Pyramids.
This attribute and the bandBlockNumber
attribute (described in bandBlockNumber Attribute) are also used to indicate bitmap masks and their pyramids. For more information about bitmap masks, bitmap mask pyramids, and how the pyramidLevel
and bandBlockNumber
attributes are used, see Bitmap Masks.
Parent topic: SDO_RASTER Object Type and the Raster Data Table
2.2.3 bandBlockNumber Attribute
The bandBlockNumber
attribute identifies the block number along the band dimension. For information about bands and layers, see Bands_ Layers_ and Metadata. For more information about how the bandBlockNumber
attribute is used with bitmap masks and their pyramids, see Bitmap Masks.
Parent topic: SDO_RASTER Object Type and the Raster Data Table
2.2.4 rowBlockNumber Attribute
The rowBlockNumber
attribute identifies the block number along the row dimension.
Parent topic: SDO_RASTER Object Type and the Raster Data Table
2.2.5 columnBlockNumber Attribute
The columnBlockNumber
attribute identifies the block number along the column dimension.
Parent topic: SDO_RASTER Object Type and the Raster Data Table
2.2.6 blockMBR Attribute
The blockMBR
attribute is the geometry (of type SDO_GEOMETRY) for the minimum bounding rectangle (MBR) for this block. The geometry is in cell space (that is, its SRID value is null), and all ordinates are integers. The ordinates represent the minimum row and column and the maximum row and column stored in this block.
Parent topic: SDO_RASTER Object Type and the Raster Data Table
2.2.7 rasterBlock Attribute
The rasterBlock
attribute contains all raster cell data for this block. It is also used to store bitmap masks of the GeoRaster object. The rasterBlock
attribute is of type BLOB.
Parent topic: SDO_RASTER Object Type and the Raster Data Table