Rasters to polygons for CartoDB

rasters.sql

--Upload your new raster data
--In my case the data goes into a table, night_light

--In some cases, I find it useful to downsample the total number of variables in a band, or in some cases merge data from multiple bands into one. 
--Here is an example how one such process would work

UPDATE night_light SET rast = ST_MapAlgebraExpr(rast,'8BUI','CASE WHEN [rast] = 0 THEN 10 WHEN [rast] = 255 THEN 11 ELSE floor([rast]/32)::int END');

--Create a new table, light_polygons
--Add a numeric column called, rast_value
--Add a numeric column called, band

--Bin raster data by value and store it in your new table

SET statement_timeout TO 0; INSERT INTO light_polygons (the_geom, rast_value, band) (select st_multi(st_makevalid((geomval).geom)) as the_geom, (geomval).val as rast_value, 1 as band from (select ST_DumpAsPolygons(rast) as geomval from night_light) f );