Changes between Version 145 and Version 146 of WKTRaster/SpecificationWorking03

Timestamp:

Jul 11, 2011, 1:53:57 PM (13 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking03

@@ -316 +316 @@
  * As an aggregate function it is using a STATE and a FINAL function materialized by a state expression (p_expression) and a final expression (f_expression) and their respective nodata value alternatives (p_nodata1expr, p_nodata2expr, p_nodatanodataexpr, f_nodata1expr and f_nodata2expr, f_nodatanodataexpr). All expressions are SQL expressions that are evaluated by the internal two raster version of ST_MapAlgebra().
 
- * An optional temporary expression (t_expression) and its nodata value alternatives (t_nodata1expr, t_nodata2expr, t_nodatanodataexpr) can be provided of used internally depending on which variant or which predefined expression is passed to ST_Union(). When it is used, MapAlgebra is called two times: one time to fill this temporary band using the t_expression and a second time to fill the first band using the p_expression. This temporary band is useful to implement some expressions needing two variables like the predefined ‘MEAN’ and ‘RANGE’ expressions.
+ * An optional temporary expression (t_expression) and its nodata value alternatives (t_nodata1expr, t_nodata2expr, t_nodatanodataexpr) can be provided of used internally depending on which variant or which predefined expression is passed to ST_Union(). When it is used, !MapAlgebra is called two times: one time to fill this temporary band using the t_expression and a second time to fill the first band using the p_expression. This temporary band is useful to implement some expressions needing two variables like the predefined ‘MEAN’ and ‘RANGE’ expressions.
 
  * The different expressions resume like this:
@@ -363 +363 @@
  -STANDARD_DEVIATION: NOT POSSIBLE, nead two passes. See how ST_SummaryStats() does it...
    
- -MAX_LENGTH, MAX_AREA or MAX_ANYTHING (require MapAlgebra being able to reference other bands then the first one):[[BR]]
+ -MAX_LENGTH, MAX_AREA or MAX_ANYTHING (requires !MapAlgebra being able to reference other bands then the first one):[[BR]]
   -p_expressions = 'CASE WHEN rast1[2] > rast2[t] THEN rast1[1] ELSE rast2[1] END', 'rast2[1]', 'rast1[1]', NULL[[BR]]
   -t_expressions = 'CASE WHEN rast1[2] > rast2[2] THEN rast1[2] ELSE rast2[2] END', 'rast2[2]', 'rast1[2]', NULL[[BR]]