[postgis-users] ST_Slope

JamesH james.holmes at newcastle.ac.uk
Tue Apr 3 06:39:45 PDT 2012


I have loaded the Slope surface created in PostGIS to OpenJump but it is
displaying as a single polygon with attributes of all the values being 1. 
Have I made a mistake when using the ST_Slope function?

The code I used is as below:

SELECT ST_AsBinary((gv).geom), (gv).val 
FROM (SELECT
ST_DumpAsPolygons(ST_Slope(ST_MapAlgebraExpr(ST_AddBand(ST_MakeEmptyRaster(10,
10, 0, 0, 0.1, 0.1, 0, 0, 4269), '8BUI'::text, 1, 0), '32BUI', '([rast.x] -
1) * 
10 + [rast.y]'), 1, '8BUI'::text)) gv 
      FROM height_newcastle 
        ) foo

Any advice again, appreciated.

Regards,
James

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