5.3 Cell Value-Based Conditional Updates (Edits)

You can update raster cell values based on conditions.

This section pertains to cell value-based raster updates and not space-based raster updates, both of which types of update are described in Querying and Updating GeoRaster Cell Data.

To update raster cell values based on conditions, you can use the SDO_GEOR_RA.rasterUpdate procedure and specify appropriate condition and vals parameters.

The condition parameter specifies an array of Boolean expressions, and the vals parameter specifies an array of arrays of math expressions. (See the raster algebra operation explanations in Raster Algebra Language). For each cell, if condition is TRUE, its cell value is updated to the result of the corresponding math expression in the vals array.

Example 5-7 Cell Value-Based Update

Example 5-7 assumes that the GeoRaster object to be updated is an image with three bands, and it calls the SDO_GEOR_RA.rasterUpdate procedure to do the following:

• For any pixels if abs(first_band_value - second_band_value)=48 and (third_band_value - second_band_value=-101), then the three band values will be updated to (123,54,89), respectively.

• For any pixels if (2*first_band_value - second_band_value/3)=108, then the three band values will be updated to (98,56,123), respectively.

Example 5-7 also includes several calls to the SDO_GEOR.getCellValue function to show "before" and "after" values.

SELECT sdo_geor.getcellvalue(georaster,0,30,30,'') FROM georaster_table WHERE georid =1;
 
SDO_GEOR.GETCELLVALUE(GEORASTER,0,30,30,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(88, 136, 35)
 
1 row selected.
 
SELECT sdo_geor.getcellvalue(georaster,0,130,130,'') FROM georaster_table WHERE georid =1;
 
SDO_GEOR.GETCELLVALUE(GEORASTER,0,130,130,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(64, 60, 48)
 
1 row selected.

SELECT sdo_geor.getcellvalue(georaster,0,230,230,'') FROM georaster_table WHERE georid =1;
 
SDO_GEOR.GETCELLVALUE(GEORASTER,0,230,230,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(11,11, 11)
 
1 row selected.
 
DECLARE
  geor   SDO_GEORASTER;
  geor1  SDO_GEORASTER;
BEGIN

  SELECT georaster into geor FROM georaster_table WHERE georid = 1;
  sdo_geor_ra.rasterUpdate(geor,0,SDO_STRING2_ARRAY('(abs({0}-{1})=48)&({2}-{1}=-101)','2*{0}-{1}/3=108'),SDO_STRING2_ARRAYSET(SDO_STRING2_ARRAY('123','54','89'),SDO_STRING2_ARRAY('98','56','123')));
END;
/
 
PL/SQL procedure successfully completed.
 
show errors;
No errors.
 
-- This pixel gets updated because it meets the first condition.
SELECT sdo_geor.getcellvalue(georaster,0,30,30,'') FROM georaster_table WHERE georid =1;

SDO_GEOR.GETCELLVALUE(GEORASTER,0,30,30,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(123, 54, 89)
 
1 row selected.
 
--This pixel gets updated because it meets the second condition.
SELECT sdo_geor.getcellvalue(georaster,0,130,130,'') FROM georaster_table WHERE georid=1;

SDO_GEOR.GETCELLVALUE(GEORASTER,0,130,130,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(98, 56, 123)
 
1 row selected.

-- This pixel keeps its original values because it does not meet any condition
-- in the "condition" array.
SELECT sdo_geor.getcellvalue(georaster,0,230,230,'') FROM georaster_table WHERE georid =1;
SDO_GEOR.GETCELLVALUE(GEORASTER,0,230,230,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(11,11, 11)
 
1 row selected.

Example 5-8 Cell Value-Based Update with nodata Parameter

Example 5-8 is basically the same as Example 5-7, except that the nodata parameter value is set to 'TRUE', so that all NODATA pixels keep their original values from the input GeoRaster object in the output GeoRaster object.

SELECT sdo_geor.getcellvalue(georaster,0,30,30,'') FROM georaster_table WHERE georid =1;
 
SDO_GEOR.GETCELLVALUE(GEORASTER,0,30,30,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(88, 136, 35)
 
1 row selected.
 
SELECT sdo_geor.getcellvalue(georaster,0,130,130,'') FROM georaster_table WHERE georid =1;
 
SDO_GEOR.GETCELLVALUE(GEORASTER,0,130,130,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(64, 60, 48)
 
1 row selected.

SELECT sdo_geor.getcellvalue(georaster,0,230,230,'') FROM georaster_table WHERE georid =1;
 
SDO_GEOR.GETCELLVALUE(GEORASTER,0,230,230,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(11,11, 11)
 
1 row selected.
 
DECLARE
  geor   SDO_GEORASTER;
  geor1  SDO_GEORASTER;
BEGIN

  SELECT georaster into geor FROM georaster_table WHERE georid = 1;
  sdo_geor.addNODATA(geor, 1,88);
  sdo_geor_ra.rasterUpdate(geor,0,SDO_STRING2_ARRAY('(abs({0}-{1})=48)&({2}-{1}=-101)','2*{0}-{1}/3=108'),SDO_STRING2_ARRAYSET(SDO_STRING2_ARRAY('123','54','89'),SDO_STRING2_ARRAY('98','56','123')),null,'true');
END;
/
 
PL/SQL procedure successfully completed.

-- This pixel keeps its original values because it is a NODATA pixel.
SELECT sdo_geor.getcellvalue(georaster,0,30,30,'') FROM georaster_table WHERE georid =1;

SDO_GEOR.GETCELLVALUE(GEORASTER,0,30,30,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(88, 136, 35)
 
1 row selected.
 
--This pixel gets updated because it meets the second condition.
SELECT sdo_geor.getcellvalue(georaster,0,130,130,'') FROM georaster_table WHERE georid=1;

SDO_GEOR.GETCELLVALUE(GEORASTER,0,130,130,'')
--------------------------------------------------------------------------------
SDO_NUMBER_ARRAY(98, 56, 123)
 
1 row selected.