PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

ST_Present and ST_Passes predicates check whether a temporal raster is created respectively at
an instant or a period of time.
Example :
SELECT ST_Present(tempRast, ’13/7/2001’::date)
FROM tempRasterTable;
SELECT ST_Passes(tempRast, ST_Range(’1/1/2008’, ’31/12/2011’))
FROM tempRasterTable;
Acting in the same way as ST_Present and ST_Passes but instead of returning a boolean,
ST_AtInstant and ST_AtPeriods operations return the temporal raster values.
Example :
SELECT ST_AtInstant(tempRast, ’13/7/2001’::date)
FROM tempRasterTable;
SELECT ST_AtPeriods(tempRast,ST_Range(’1/1/2008’,’31/12/2011’))
FROM tempRasterTable;
In addition, there are also some aggregate functions [13] that execute on multiple temporal raster
values. These values are grouped together as input. The output is a single value computed based
on certain criteria. An example of a simple aggregate function is ST_Sum that calculates the sum of
a sequence of temporal raster values. As each temporal raster is a matrix of values of each point in
space at a time instant, the computation of the sum of this sequence goes back to the computation of
the sum of values of each corresponding point. The output is a summing raster.
Pseudo code of ST_Sum:
WHILE (band