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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Dear List,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>First of all, I wish to congratulate the postgis developers with the (new to me) raster functionality. It’s a real game changer.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am experimenting with (free!) Landsat-8 data, generating indices through queries. Landsat-8 bands come as 16BUI type data.<o:p></o:p></p><p class=MsoNormal>In order to avoid integer division issues, I cast to 32BF as follows:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>select st_reclass(rast, ‘0-65535:0-65535’, ‘32BF’) from l8tiled where rid = 5644 -- l8tiles holds the tiled single-band rasters, rid is an arbitrary tile ID<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>OR<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>select st_mapalgebra(rast, ‘32BF’, ‘[rast]’) from l8tiled where rid = 5644 <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Both work, with the first being the fastest (because implement directly in C). 11 and 21 ms for a 64 by 64 pixel tile, respectively (on Linux 64 bit/Dell T7400 PostgreSQL 9.3/Postgis 2.1).<o:p></o:p></p><p class=MsoNormal>The first is not very elegant, though, as it requires the somewhat awkward reclassexpr. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Is there a neater way to do this? If I use ‘’ (empty string) for the reclassexpr, the cast does not work (i.e. the result remains 16BUI).<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>Guido Lemoine<o:p></o:p></p></div></body></html>