Changes between Version 111 and Version 112 of WKTRaster/SpecificationWorking03

Timestamp:

06/13/11 15:15:50 (14 years ago)

Author:

pracine

Comment:

—

WKTRaster/SpecificationWorking03

@@ -146 +146 @@
 '''Details for 5) to 8) Two rasters versions'''
 
- Both rasters must have the same SRID. If not, ST_MapAlgebra should return an error: "ERROR:  Operation on two geometries with different SRIDs"
-
- Both raster must be aligned. This is determined using the ST_SameAlignment() function described below. If a resampling is necessary they use the planned ST_Resample() function to resample the second raster to the first one before processing (or the first to the second if an optional parameter is provided). If ST_Resample() is not yet implemented when these functions are implemented, just return an error message: "ERROR:  MapAlgebra on rasters with different alignment not yet implemented."
-
- Both raster must overlap. This is determined using ST_Intersects(raster, raster) (to be implemented). If they don't overlap an empty raster is returned.
+ -Both rasters must have the same SRID. If not, ST_MapAlgebra should return an error: "ERROR:  Operation on two geometries with different SRIDs"
+
+ -Both raster must be aligned. This is determined using the ST_SameAlignment() function described below. If a resampling is necessary they use the planned ST_Resample() function to resample the second raster to the first one before processing (or the first to the second if an optional parameter is provided). If ST_Resample() is not yet implemented when these functions are implemented, just return an error message: "ERROR:  MapAlgebra on rasters with different alignment not yet implemented."
+
+ -Both raster must overlap. This is determined using ST_Intersects(raster, raster) (to be implemented). If they don't overlap an empty raster is returned.
 
  One of the implications of this is that users should add a WHERE clause to avoid useless computation with non-overlapping rasters. This is the same principle as with ST_Intersection(). Hence:
@@ -157 +157 @@
   SELECT ST_MapAlgebra(rast1, rast2, mathExpr) FROM mytable
 
- The computation extent can be FIRST, SECOND, INTERSECTION, UNION.
+ -The computation extent (extentexpr in the functions below) can be:
+
+  -'FIRST' (the extent of the first raster),[[BR]]
+  -'SECOND' (the extent of the first raster),[[BR]]
+  -'INTERSECTION' (the extent of the intersection of both rasters),[[BR]]
+  -'UNION' (the extent of the union of both rasters).
 
  Replacement expressions can be provided as parameter for when:
 
-  -The first raster value is nodata[[BR]]
-  -The second raster value is nodata[[BR]]
-  -Both rasters values when they are both nodata
-
-'''ST_MapAlgebraExpr(raster rast, integer band, text expression, text nodatavalueexpr, text pixeltype) -> raster'''
+  -The first raster value is nodata (nodata1expr in the functions below)[[BR]]
+  -The second raster value is nodata (nodata2expr in the functions below)[[BR]]
+  -Both rasters values when they are both nodata (nodatanodataexpr in the functions below)
+
+'''5) ST_MapAlgebraExpr(rast1 raster, band1 integer, rast2 raster, band2 integer, expression text, pixeltype text, extentexpr text, nodata1expr text, nodata2expr text, nodatanodataexpr text) -> raster'''
 
  '''Open Question:'''