Database Reference
In-Depth Information
• The last four function parameters (
'1.'
,
'6.'
,
'7.5'
,
'2.5'
) are user-
definedargumentsthatarepassedforprocessingbythe
callback
function.
• Theorderofthebandnumbersaffectstheorderofthepixelvaluespassed
to the callback function.
ThefollowingscreenshotshowstheMODISrasterbeforeandafterrunningtheEVI
operation.TheEVIrasterhasapalewhitetodarkgreencolormapappliedforhigh-
lighting areas of high vegetation.
If you are unable to run the standard EVI operation or want more practice, we will
now compute a two-band EVI. We will use the function
ST_MapAlgebraFct()
.
Note
Pleasenotethat
ST_MapAlgebraFct()
isdeprecatedinPostGIS2.1andmay
be removed in the future versions.
For the two-band EVI, we will use the following
callback
function. The two band
EVI is computed with this equation:
CREATE OR REPLACE FUNCTION
chap5.modis_evi2(value1 double precision,
