ST_MapAlgebra (callback function version) — Callback function version - Returns a one-band raster given one or more input rasters, band indexes and one user-specified callback function.
raster ST_MapAlgebra(
rastbandarg[] rastbandargset, regprocedure callbackfunc, text pixeltype=NULL, text extenttype=INTERSECTION, raster customextent=NULL, integer distancex=0, integer distancey=0, text[] VARIADIC userargs=NULL)
;
raster ST_MapAlgebra(
raster rast, integer[] nband, regprocedure callbackfunc, text pixeltype=NULL, text extenttype=FIRST, raster customextent=NULL, integer distancex=0, integer distancey=0, text[] VARIADIC userargs=NULL)
;
raster ST_MapAlgebra(
raster rast, integer nband, regprocedure callbackfunc, text pixeltype=NULL, text extenttype=FIRST, raster customextent=NULL, integer distancex=0, integer distancey=0, text[] VARIADIC userargs=NULL)
;
raster ST_MapAlgebra(
raster rast1, integer nband1, raster rast2, integer nband2, regprocedure callbackfunc, text pixeltype=NULL, text extenttype=INTERSECTION, raster customextent=NULL, integer distancex=0, integer distancey=0, text[] VARIADIC userargs=NULL)
;
raster ST_MapAlgebra(
raster rast, integer nband, regprocedure callbackfunc, float8[] mask, boolean weighted, text pixeltype=NULL, text extenttype=INTERSECTION, raster customextent=NULL, text[] VARIADIC userargs=NULL)
;
Returns a one-band raster given one or more input rasters, band indexes and one user-specified callback function.
rast,rast1,rast2, rastbandargset
Rasters on which the map algebra process is evaluated.
rastbandargset
allows the use of a map algebra operation on many rasters and/or many bands. See example Variant 1.
nband, nband1, nband2
Band numbers of the raster to be evaluated. nband can be an integer or integer[] denoting the bands. nband1 is band on rast1 and nband2 is band on rast2 for the 2 raster/2band case.
callbackfunc
The callbackfunc
parameter must be the name and signature of an SQL or PL/pgSQL function, cast to a regprocedure. An example PL/pgSQL function example is:
CREATE OR REPLACE FUNCTION sample_callbackfunc(value double precision[][][], position integer[][], VARIADIC userargs text[]) RETURNS double precision AS $$ BEGIN RETURN 0; END; $$ LANGUAGE 'plpgsql' IMMUTABLE;
The callbackfunc
must have three arguments: a 3-dimension double precision array, a 2-dimension integer array and a variadic 1-dimension text array. The first argument value
is the set of values (as double precision) from all input rasters. The three dimensions (where indexes are 1-based) are: raster #, row y, column x. The second argument position
is the set of pixel positions from the output raster and input rasters. The outer dimension (where indexes are 0-based) is the raster #. The position at outer dimension index 0 is the output raster's pixel position. For each outer dimension, there are two elements in the inner dimension for X and Y. The third argument userargs
is for passing through any user-specified arguments.
Passing a regprocedure argument to a SQL function requires the full function signature to be passed, then cast to a regprocedure type. To pass the above example PL/pgSQL function as an argument, the SQL for the argument is:
'sample_callbackfunc(double precision[], integer[], text[])'::regprocedure
Note that the argument contains the name of the function, the types of the function arguments, quotes around the name and argument types, and a cast to a regprocedure.
mask
An n-dimensional array (matrix) of numbers used to filter what cells get passed to map algebra call-back function. 0 means a neighbor cell value should be treated as no-data and 1 means value should be treated as data. If weight is set to true, then the values, are used as multipliers to multiple the pixel value of that value in the neighborhood position.
weighted
boolean (true/false) to denote if a mask value should be weighted (multiplied by original value) or not (only applies to proto that takes a mask).
pixeltype
If pixeltype
is passed in, the one band of the new raster will be of that pixeltype. If pixeltype is passed NULL or left out, the new raster band will have the same pixeltype as the specified band of the first raster (for extent types: INTERSECTION, UNION, FIRST, CUSTOM) or the specified band of the appropriate raster (for extent types: SECOND, LAST). If in doubt, always specify pixeltype
.
The resulting pixel type of the output raster must be one listed in ST_BandPixelType or left out or set to NULL.
extenttype
Possible values are INTERSECTION (default), UNION, FIRST (default for one raster variants), SECOND, LAST, CUSTOM.
customextent
If extentype
is CUSTOM, a raster must be provided for customextent
. See example 4 of Variant 1.
distancex
The distance in pixels from the reference cell in x direction. So width of resulting matrix would be 2*distancex + 1
.If not specified only the reference cell is considered (neighborhood of 0).
distancey
The distance in pixels from reference cell in y direction. Height of resulting matrix would be 2*distancey + 1
.If not specified only the reference cell is considered (neighborhood of 0).
userargs
The third argument to the callbackfunc
is a variadic text array. All trailing text arguments are passed through to the specified callbackfunc
, and are contained in the userargs
argument.
For more information about the VARIADIC keyword, please refer to the PostgreSQL documentation and the "SQL Functions with Variable Numbers of Arguments" section of Query Language (SQL) Functions. |
The text[] argument to the |
Variant 1 accepts an array of rastbandarg
allowing the use of a map algebra operation on many rasters and/or many bands. See example Variant 1.
Variants 2 and 3 operate upon one or more bands of one raster. See example Variant 2 and 3.
Variant 4 operate upon two rasters with one band per raster. See example Variant 4.
Availability: 2.2.0: Ability to add a mask
Disponibilidad: 2.1.0
One raster, one band
WITH foo AS ( SELECT 1 AS rid, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0) AS rast ) SELECT ST_MapAlgebra( ARRAY[ROW(rast, 1)]::rastbandarg[], 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure ) AS rast FROM foo
One raster, several bands
WITH foo AS ( SELECT 1 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0), 2, '8BUI', 10, 0), 3, '32BUI', 100, 0) AS rast ) SELECT ST_MapAlgebra( ARRAY[ROW(rast, 3), ROW(rast, 1), ROW(rast, 3), ROW(rast, 2)]::rastbandarg[], 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure ) AS rast FROM foo
Several rasters, several bands
WITH foo AS ( SELECT 1 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0), 2, '8BUI', 10, 0), 3, '32BUI', 100, 0) AS rast UNION ALL SELECT 2 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 1, 1, -1, 0, 0, 0), 1, '16BUI', 2, 0), 2, '8BUI', 20, 0), 3, '32BUI', 300, 0) AS rast ) SELECT ST_MapAlgebra( ARRAY[ROW(t1.rast, 3), ROW(t2.rast, 1), ROW(t2.rast, 3), ROW(t1.rast, 2)]::rastbandarg[], 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure ) AS rast FROM foo t1 CROSS JOIN foo t2 WHERE t1.rid = 1 AND t2.rid = 2
Complete example of tiles of a coverage with neighborhood. This query only works with PostgreSQL 9.1 or higher.
WITH foo AS ( SELECT 0 AS rid, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0) AS rast UNION ALL SELECT 1, ST_AddBand(ST_MakeEmptyRaster(2, 2, 2, 0, 1, -1, 0, 0, 0), 1, '16BUI', 2, 0) AS rast UNION ALL SELECT 2, ST_AddBand(ST_MakeEmptyRaster(2, 2, 4, 0, 1, -1, 0, 0, 0), 1, '16BUI', 3, 0) AS rast UNION ALL SELECT 3, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, -2, 1, -1, 0, 0, 0), 1, '16BUI', 10, 0) AS rast UNION ALL SELECT 4, ST_AddBand(ST_MakeEmptyRaster(2, 2, 2, -2, 1, -1, 0, 0, 0), 1, '16BUI', 20, 0) AS rast UNION ALL SELECT 5, ST_AddBand(ST_MakeEmptyRaster(2, 2, 4, -2, 1, -1, 0, 0, 0), 1, '16BUI', 30, 0) AS rast UNION ALL SELECT 6, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, -4, 1, -1, 0, 0, 0), 1, '16BUI', 100, 0) AS rast UNION ALL SELECT 7, ST_AddBand(ST_MakeEmptyRaster(2, 2, 2, -4, 1, -1, 0, 0, 0), 1, '16BUI', 200, 0) AS rast UNION ALL SELECT 8, ST_AddBand(ST_MakeEmptyRaster(2, 2, 4, -4, 1, -1, 0, 0, 0), 1, '16BUI', 300, 0) AS rast ) SELECT t1.rid, ST_MapAlgebra( ARRAY[ROW(ST_Union(t2.rast), 1)]::rastbandarg[], 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure, '32BUI', 'CUSTOM', t1.rast, 1, 1 ) AS rast FROM foo t1 CROSS JOIN foo t2 WHERE t1.rid = 4 AND t2.rid BETWEEN 0 AND 8 AND ST_Intersects(t1.rast, t2.rast) GROUP BY t1.rid, t1.rast
Example like the prior one for tiles of a coverage with neighborhood but works with PostgreSQL 9.0.
WITH src AS ( SELECT 0 AS rid, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0) AS rast UNION ALL SELECT 1, ST_AddBand(ST_MakeEmptyRaster(2, 2, 2, 0, 1, -1, 0, 0, 0), 1, '16BUI', 2, 0) AS rast UNION ALL SELECT 2, ST_AddBand(ST_MakeEmptyRaster(2, 2, 4, 0, 1, -1, 0, 0, 0), 1, '16BUI', 3, 0) AS rast UNION ALL SELECT 3, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, -2, 1, -1, 0, 0, 0), 1, '16BUI', 10, 0) AS rast UNION ALL SELECT 4, ST_AddBand(ST_MakeEmptyRaster(2, 2, 2, -2, 1, -1, 0, 0, 0), 1, '16BUI', 20, 0) AS rast UNION ALL SELECT 5, ST_AddBand(ST_MakeEmptyRaster(2, 2, 4, -2, 1, -1, 0, 0, 0), 1, '16BUI', 30, 0) AS rast UNION ALL SELECT 6, ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, -4, 1, -1, 0, 0, 0), 1, '16BUI', 100, 0) AS rast UNION ALL SELECT 7, ST_AddBand(ST_MakeEmptyRaster(2, 2, 2, -4, 1, -1, 0, 0, 0), 1, '16BUI', 200, 0) AS rast UNION ALL SELECT 8, ST_AddBand(ST_MakeEmptyRaster(2, 2, 4, -4, 1, -1, 0, 0, 0), 1, '16BUI', 300, 0) AS rast ) WITH foo AS ( SELECT t1.rid, ST_Union(t2.rast) AS rast FROM src t1 JOIN src t2 ON ST_Intersects(t1.rast, t2.rast) AND t2.rid BETWEEN 0 AND 8 WHERE t1.rid = 4 GROUP BY t1.rid ), bar AS ( SELECT t1.rid, ST_MapAlgebra( ARRAY[ROW(t2.rast, 1)]::rastbandarg[], 'raster_nmapalgebra_test(double precision[], int[], text[])'::regprocedure, '32BUI', 'CUSTOM', t1.rast, 1, 1 ) AS rast FROM src t1 JOIN foo t2 ON t1.rid = t2.rid ) SELECT rid, (ST_Metadata(rast)), (ST_BandMetadata(rast, 1)), ST_Value(rast, 1, 1, 1) FROM bar;
One raster, several bands
WITH foo AS ( SELECT 1 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0), 2, '8BUI', 10, 0), 3, '32BUI', 100, 0) AS rast ) SELECT ST_MapAlgebra( rast, ARRAY[3, 1, 3, 2]::integer[], 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure ) AS rast FROM foo
One raster, one band
WITH foo AS ( SELECT 1 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0), 2, '8BUI', 10, 0), 3, '32BUI', 100, 0) AS rast ) SELECT ST_MapAlgebra( rast, 2, 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure ) AS rast FROM foo
Two rasters, two bands
WITH foo AS ( SELECT 1 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 0, 1, -1, 0, 0, 0), 1, '16BUI', 1, 0), 2, '8BUI', 10, 0), 3, '32BUI', 100, 0) AS rast UNION ALL SELECT 2 AS rid, ST_AddBand(ST_AddBand(ST_AddBand(ST_MakeEmptyRaster(2, 2, 0, 1, 1, -1, 0, 0, 0), 1, '16BUI', 2, 0), 2, '8BUI', 20, 0), 3, '32BUI', 300, 0) AS rast ) SELECT ST_MapAlgebra( t1.rast, 2, t2.rast, 1, 'sample_callbackfunc(double precision[], int[], text[])'::regprocedure ) AS rast FROM foo t1 CROSS JOIN foo t2 WHERE t1.rid = 1 AND t2.rid = 2
WITH foo AS (SELECT ST_SetBandNoDataValue( ST_SetValue(ST_SetValue(ST_AsRaster( ST_Buffer( ST_GeomFromText('LINESTRING(50 50,100 90,100 50)'), 5,'join=bevel'), 200,200,ARRAY['8BUI'], ARRAY[100], ARRAY[0]), ST_Buffer('POINT(70 70)'::geometry,10,'quad_segs=1') ,50), 'LINESTRING(20 20, 100 100, 150 98)'::geometry,1),0) AS rast ) SELECT 'original' AS title, rast FROM foo UNION ALL SELECT 'no mask mean value' AS title, ST_MapAlgebra(rast,1,'ST_mean4ma(double precision[], int[], text[])'::regprocedure) AS rast FROM foo UNION ALL SELECT 'mask only consider neighbors, exclude center' AS title, ST_MapAlgebra(rast,1,'ST_mean4ma(double precision[], int[], text[])'::regprocedure, '{{1,1,1}, {1,0,1}, {1,1,1}}'::double precision[], false) As rast FROM foo UNION ALL SELECT 'mask weighted only consider neighbors, exclude center multi other pixel values by 2' AS title, ST_MapAlgebra(rast,1,'ST_mean4ma(double precision[], int[], text[])'::regprocedure, '{{2,2,2}, {2,0,2}, {2,2,2}}'::double precision[], true) As rast FROM foo;
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