SDO_GEOR.setDefaultAlpha

Format

SDO_GEOR.setDefaultAlpha(
     georaster     IN OUT SDO_GEORASTER, 
     defaultAlpha  IN NUMBER);

Description

Sets the number of the layer to be used for the alpha color component (in the RGBA color space) for displaying a GeoRaster object, or deletes the existing value if you specify a null defaultAlpha parameter.

Parameters

georaster: GeoRaster object.
defaultAlpha: Number of the layer to be used for the alpha color component (in the RGBA color space) for displaying the specified GeoRaster object. Must be greater than 0 (zero) and less than or equal to the highest layer number in the GeoRaster object.

Usage Notes

The default red, green, blue, and alpha values are used for true-color displays, not for pseudocolor or grayscale displays. These values are optional, and they are intended for use only when visualizing multilayer or hyperspectral GeoRaster objects.

The GeoRaster object is automatically validated after the operation completes.

An exception is raised if you are trying to set the number of the layer to be used for the alpha color component only, or if defaultAlpha is not a valid layer number for the GeoRaster object.

Examples

The following example sets the default red, green, blue, and alpha color layers for the GeoRaster objects (GEORASTER column) in the GEORASTER_TABLE table, and it returns an array with the layer numbers for the red, green, blue, and alpha color components for displaying these GeoRaster objects. (The GEORASTER_TABLE table definition is presented after Example 1-1 in Storage Parameters.)

DECLARE
  grobj sdo_georaster;
BEGIN
  SELECT georaster INTO grobj FROM georaster_table WHERE georid=4 FOR UPDATE;
  sdo_geor.setDefaultRed(grobj, 5);
  sdo_geor.setDefaultGreen(grobj, 4);
  sdo_geor.setDefaultBlue(grobj, 3);
  sdo_geor.setDefaultAlpha(grobj, 2);
  UPDATE georaster_table SET georaster = grobj WHERE georid=4;
  COMMIT;
END;
/

SELECT sdo_geor.getDefaultColorLayer(georaster) FROM georaster_table
  WHERE georid=4;
 
SDO_GEOR.GETDEFAULTCOLORLAYER(GEORASTER)
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(5, 4, 3, 2)
 
1 row selected.