SDO_GEOR.mosaic

Format

SDO_GEOR.mosaic(
     georasterTableName  IN VARCHAR2, 
     georasterColumnName IN VARCHAR2, 
     georaster           IN OUT SDO_GEORASTER, 
     storageParam        IN VARCHAR2, 
     bgValues            IN SDO_NUMBER_ARRAY DEFAULT NULL);

Description

Mosaics a set of source GeoRaster objects that are rectified, are geospatially aligned under the same SRID, and have the same resolution.

Parameters

georasterTableName

Name of the table or view containing all source GeoRaster objects.

georasterColumnName

Column of type SDO_GEORASTER in georasterTableName.

georaster

GeoRaster object to hold the result of the mosaic operation. Cannot be the same as any GeoRaster object in georasterColumnName in georasterTableName.

storageParam

A string specifying storage parameters, as explained in Storage Parameters. If this parameter is null, the resulting GeoRaster object has the same storage parameters (blockSize, cellDepth, interleaving, and compression) as the upper-left corner source GeoRaster object in the model space (if applicable) or cell space. However, it is recommended that you specify the storage parameters, particularly the blocking size, as appropriate for the size of the output mosaic, unless you want the mosaic to have the same storage parameters as those of the upper-left corner GeoRaster object to be mosaicked.

bgValues

Background values for filling partially empty raster blocks. It is only useful when the current operation leads to partially empty raster blocks (see Empty Raster Blocks), which could happen when the source GeoRaster objects have empty raster blocks or when the source GeoRaster objects do not cover the whole area. The number of elements in the SDO_NUMBER_ARRAY object must be either one (same filling value used for all bands) or the band dimension size (a different filling value for each band, respectively). For example, SDO_NUMBER_ARRAY(1,5,10) fills the first band with 1, the second band with 5, and the third band with 10. The default bgValues are zero (0).

The filling values must be valid cell values as specified by the target cell depth background values for filling sparse data.

Usage Notes

This procedure has limited mosaicking capabilities, and works well for preprocessed and perfectly aligned source GeoRaster objects only. It does not work on unrectified rasters and does not support parallel processing. For advanced mosaicking capabilities, including parallel processing, use the SDO_GEOR_AGGR.mosaicSubset procedure. See Large-Scale Image Mosaicking for more information.

For this procedure, the source GeoRaster objects must be prepared images or raster data so that they can be mosaicked directly. The GeoRaster objects to be mosaicked must:

Not be a mixture of georeferenced and nongeoreferenced objects. Either all of the objects are georeferenced, or none of the objects is georeferenced.
Have the same SRID value if the objects are georeferenced, and the georeferencing method must be affine transformation. The affine transformations of the GeoRaster objects must have the same set of coefficients (A, B, D and E) or (b, c, e, f). This means that the images must have the same X resolution and Y resolution (although the X and Y resolutions do not have to be the same), the same rotation angle, and the same skewing factor; in other words, the images must have the same resolutions, and be rotated and skewed in the same way if the images are rotated and skewed.
Have the same number of layers or bands. There is no restriction on the row and column dimension sizes of the source objects; for example, they do not need to be a power of 2.
Have the same mapping between band number and layers.

If the GeoRaster objects to be mosaicked are georeferenced, they are co-located according to their georeferencing information. If the GeoRaster objects are not georeferenced, they are co-located according to their ULTCoordinate values. (The ULTCoordinate is explained in GeoRaster Data Model.)

If applicable, the resulting GeoRaster object takes the spatial reference metadata information from the upper-left corner source GeoRaster object in the model space. It also takes the cell space and any default storage attributes from the upper-left corner source GeoRaster object in the model space.

If the source GeoRaster objects have empty raster blocks or do not cover the whole area, the mosaicked result GeoRaster object may have empty or partially empty raster blocks (see Empty Raster Blocks). A result raster block that is not covered by any of the source GeoRaster objects is kept empty. Any partially empty raster blocks are filled with the values specified in the bgValues parameter, or with 0 if the bgValues parameter is not specified.

If the source GeoRaster objects overlap, data of the overlapping area comes from the source object that covers it and that has the largest ultCoordinate in the cell space where all the source objects are co-located.

Any bitmap masks associated with the source GeoRaster objects are not considered, and the bitmapmask parameter is ignored if it is specified in the storageParam string.

If all source GeoRaster objects are blank and have the same blankCellValue value, the resulting GeoRaster object is blank and has that blankCellValue value; otherwise, the resulting GeoRaster object is not blank.

The GeoRaster object to contain the results of the mosaic operation (georaster parameter) must not be any of the source GeoRaster objects (the objects on which the mosaic operation is performed).

The mosaic operation performs internal commit operations at regular intervals, and thus it cannot be rolled back. If the operation is interrupted, dangling raster blocks may exist in the raster data table. You can handle dangling raster blocks by maintaining GeoRaster objects and system data in the database, as explained in Maintaining GeoRaster Objects and System Data in the Database.

Examples

The following example inserts an initialized GeoRaster object into the GEORASTER_TABLE table, returns the GeoRaster object into a variable named gr, mosaics all the GeoRaster objects in the GROBJ column of a table named GRTAB, and stores the resulting mosaicked GeoRaster object in the same variable. (The GEORASTER_TABLE table definition is presented after Example 1-1 in Storage Parameters. The GRTAB table definition is not important to the example and is not presented here.)

DECLARE
  gr sdo_georaster;
BEGIN
  INSERT INTO georaster_table (georid, georaster) 
      VALUES (12, sdo_geor.init('rdt_1'))
      RETURNING georaster INTO gr;
  sdo_geor.mosaic('grtab', 'grobj', gr, 'blocking=optimalpadding blocksize=(512,512,1)');
  UPDATE georaster_table SET georaster=gr WHERE id=12;
END;
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