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WCPS-Tutorial / Conditional selection: how to select coverages of interest

When addressing multiple coverages as introduced before it is not always desirable to get back each coverage; for a given large set of coverages usually one wants to select coverages of interest and discard the rest. To this end, a request can contain a where clause which filters coverages.

Example: "Landsat scenes s1, s1, and s3, but only those images where a threshold of 127 is exceeded in the near-infrared band."

for s in ( s1, s2, s3 )
where
	max( s.nir ) > 127
return
	encode( s, "tiff" )

See manual: coverageListExpr

Background information:

  • The WCPS where clause serves the same purpose and has the same mechanis as the SQL where clause.