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I need to make some calculations with data from raster files saved in my postgis database. I need, build a map, using the average from a set of these raster files, for example.

Besides, I need to make others similar operations like the max value of a set of rasters, among others.

I did'nt see nothing to do operations like it directly on PostGIS (http://postgis.net/docs/manual-2.1/RT_reference.html), there are functions to do it? Besides, I'm worried with the performance, because if I have a lot of raster files, maybe can be better solve these calculations with R, by example, or not?

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Section 9.9. Raster Band Statistics and Analytics is all about getting statistics from pixel values http://postgis.net/docs/manual-2.1/RT_reference.html#RasterBand_Stats

You can get the count, the sum, the mean, the stddev, the min and the max with ST_SummaryStats().

If your raster is tiled, use ST_SummaryStatsAgg() to aggregate the stats from many tiles.

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  • Thanks for your answer, its really works. But I would like execute ST_SummaryStats() in a set of rasters. Extract the average of two or more rasters. Its possible ? Thanks
    – mkdev
    Commented Jan 18, 2016 at 12:54
  • That's what ST_SummaryStatsAgg() is also for... In PostGIS, a raster is no different from a tile. A tile is a raster and a raster can be a tile depending on the context.
    – Pierre Racine
    Commented Jan 19, 2016 at 18:25
  • Thank you, I found the way to process it through ST_SummaryStatsAgg(). Thanks
    – mkdev
    Commented Sep 27, 2020 at 2:58

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