[postgis-users] NDVI Calculation from two bands within one Raster
james.holmes at newcastle.ac.uk
Wed Apr 11 07:56:23 PDT 2012
Sorry to keep reviving this thread, espcially with a basic question.
I am using:
SELECT ST_MapAlgebraExpr(a.rast, 4, b.rast, 3, '([rast1] - [rast2])
/([rast1] + [rast2])::float')
WHEN (rast1 + rast2 = 0) THEN = 999 ELSE ([rast1] - [rast2]) /([rast1] +
FROM ndvi a, ndvi b;
Where the WHEN statement is being used to prevent the error division by
However this returns: syntax error at or near "WHEN"
Can anyone advise on where I'm structuring this query wrongly.
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