Format

SDO_GEOR.getDefaultAlpha(
     georaster  IN SDO_GEORASTER 
     ) RETURN NUMBER;

Description

Returns the number of the layer to be used for the alpha color component (in the RGBA color space) for displaying a GeoRaster object. If this value is not set in the metadata, a null value is returned.

Parameters

georaster

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.

You can return the layer numbers for all four color components (RGBA) by using the SDO_GEOR.getDefaultColorLayer function.

Examples

The following example returns the layer numbers for the red, green, blue, and alpha color components for displaying the GeoRaster objects in the table named GEORASTER_TABLE, whose definition is presented after Example 1-1 in Storage Parameters.

SELECT georid, sdo_geor.getDefaultRed(georaster) red,
  sdo_geor.getDefaultGreen(georaster) green,
  sdo_geor.getDefaultBlue(georaster) blue,
  sdo_geor.getDefaultAlpha(georaster) alpha
FROM georaster_table;
 
    GEORID        RED      GREEN       BLUE      ALPHA
---------- ---------- ---------- ---------- ----------
         1          1          2          3          4
         2
         3         31         20         13         10