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Added ST_Slope map algebra neighborhood shortcut function.
git-svn-id: http://svn.osgeo.org/postgis/trunk@8264 b70326c6-7e19-0410-871a-916f4a2858ee
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@ -1945,6 +1945,30 @@ CREATE OR REPLACE FUNCTION st_range4ma(matrix float[][], nodatamode text, variad
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$$
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LANGUAGE 'plpgsql' IMMUTABLE;
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CREATE OR REPLACE FUNCTION _st_slope4ma(matrix float[][], nodatamode text, variadic args text[])
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RETURNS float
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AS
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$$
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DECLARE
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pwidth float;
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pheight float;
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dz_dx float;
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dz_dy float;
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BEGIN
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pwidth := args[1]::float;
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pheight := args[2]::float;
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dz_dx := ((matrix[3][1] + 2.0 * matrix[3][2] + matrix[3][3]) - (matrix[1][1] + 2.0 * matrix[1][2] + matrix[1][3])) / (8.0 * pwidth);
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dz_dy := ((matrix[1][3] + 2.0 * matrix[2][3] + matrix[3][3]) - (matrix[1][1] + 2.0 * matrix[2][1] + matrix[3][1])) / (8.0 * pheight);
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RETURN atan(sqrt(pow(dz_dx, 2.0) + pow(dz_dy, 2.0)));
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END;
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$$
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LANGUAGE 'plpgsql' IMMUTABLE;
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CREATE OR REPLACE FUNCTION st_slope(rast raster, band integer, pixeltype text)
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RETURNS RASTER
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AS $$ SELECT st_mapalgebrafctngb($1, $2, $3, 1, 1, '_st_slope4ma(float[][], text, text[])'::regprocedure, 'value', st_pixelwidth($1)::text, st_pixelheight($1)::text) $$
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LANGUAGE 'SQL' STABLE;
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-----------------------------------------------------------------------
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-- Get information about the raster
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@ -96,3 +96,26 @@ SELECT
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) = 9
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FROM ST_SetValue(ST_TestRasterNgb(3, 3, 10), 3, 3, NULL) AS rast;
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-- test st_slope, flat plane
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SELECT
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ST_Value(rast, 2, 2) = 1,
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ST_Value(
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ST_Slope(rast, 1, NULL), 2, 2
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) = 0
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FROM ST_TestRasterNgb(3, 3, 1) AS rast;
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-- test st_slope, corner spike
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SELECT
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ST_Value(rast, 2, 2) = 1,
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round(degrees(ST_Value(
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ST_Slope(rast, 1, NULL), 2, 2
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))*100000) = 5784902 -- this measurement is in radians
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FROM ST_SetValue(ST_TestRasterNgb(3, 3, 1), 1, 1, 10) AS rast;
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-- test st_slope, corner droop
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SELECT
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ST_Value(rast, 2, 2) = 10,
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round(degrees(ST_Value(
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ST_Slope(rast, 1, NULL), 2, 2
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))*100000) = 5784902 -- this measurement is in radians
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FROM ST_SetValue(ST_TestRasterNgb(3, 3, 10), 1, 1, 1) AS rast;
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@ -18,3 +18,6 @@ t|t
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NOTICE: Neighborhood NODATA behavior defaulting to 'ignore'
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t|t
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t|t
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t|t
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t|t
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t|t
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