Changes between Version 171 and Version 172 of WKTRaster/SpecificationWorking03

Timestamp:

11/11/11 07:01:41 (13 years ago)

Author:

dzwarg

Comment:

Clarified neighborhood sizes to ST_MapAlgebraFctNgb

WKTRaster/SpecificationWorking03

@@ -127 +127 @@
 
    Pierre: They ARE arguments to the user function as are 2 and 2 in this example. But all user function MUST accept at least these three parameters.
+
+   DZ: The user function can determine the dimensions of the neighborhood from the incoming 2-dimensional array, so the user function must accept: neighborhood float[][], nodataflag text, variadic args text[].  It is not necessary to pass the neighborhood dimensions to the user function. They are still required in the main ST_MapAlgebraFctNgb function, as it must construct the neighborhood array. 
 
  Any remaining parameters to ST_MapAlgebraNgb could be passed to the summarizing functions for its own need (e.g. "round" to specify that only the pixel forming a circle should be used in the computing).