[raster] ST_Neighborhood

[Bborie Park]

Along with ST_NearestValue(), a related function is to get the all pixels within N pixel distance from a specific pixel (excluding the specific pixel). The function returns a set of records (x, y, pixel value) that can used for additional processing…

ST_Neighborhood(
	rast raster, band integer,
	ix integer, iy integer,
	distance integer,
	exclude_nodata_value boolean DEFAULT TRUE,
	OUT x integer, OUT y integer,
	OUT val double precision
) -> SETOF record

distance: value greater than zero denoting the size of the neighborhood around the specified pixel. So a value of 4 would be all pixels within the box made by 4 pixels to the left of, 4 pixels to the right of, 4 pixels above and 4 pixels below the specific pixel

ST_Neighborhood(
	rast raster,
	ix integer, iy integer,
	distance integer,
	exclude_nodata_value boolean DEFAULT TRUE,
	OUT x integer, OUT y integer,
	OUT val double precision
) -> SETOF record

ST_Neighborhood(
	rast raster, band integer,
	pt geometry,
	distance integer,
	exclude_nodata_value boolean DEFAULT TRUE,
	OUT x integer, OUT y integer,
	OUT val double precision
) -> SETOF record

ST_Neighborhood(
	rast raster,
	pt geometry,
	distance integer,
	exclude_nodata_value boolean DEFAULT TRUE,
	OUT x integer, OUT y integer,
	OUT val double precision
) -> SETOF record

[pracine]

Could the result be formatted properly so that we can pass it directly to one of the st_…4ma already existing functions?

SELECT ST_Max4Ma(ST_Neighborhood(rast, 1, 3.14))

?

[Bborie Park]

Would the following work?

SELECT ST_Max4Ma((ST_Neighborhood(rast, 1, 3.14)).val)

The format of returning a set of (x, y, val) is so that someone could go nuts with the results, such as weighted averages based upon distance.

[Bborie Park]

After looking at the ST_xx4ma functions, I adjust the output of the ST_Neighborhood to double precision[][] since I haven't started using ST_Neighborhood for my in-house needs.

[Bborie Park]

Committed in r9786