Dear List,
I am dabbling with some Landsat-8 imagery in PostGIS, using raster functionality. I am primarily interested in deriving polygon-delineated extracts from the various spectral bands (e.g. for a forest patch, an agricultural field, etc). Landsat-8 provides the so-called BQA band (see http://landsat.usgs.gov/L8QualityAssessmentBand.php) which is a bit-coded set of quality parameters, for which the cloud and haze indicators (bits 12-15 (right to left)) are the most important (for me). I would want to mask out all pixels, in the spectral band(s), for which these bits are set in the BQA band. Did anyone come across a solution that would address this kind of masking operation? The only reference I seem to be able to find is the statement that "no masks (you can create a mask as a band)" in the WKTRaster wiki page on osgeo, which is somewhat cryptic. I would know how to do this outside the database (using JAI), but it seems that masking is some core operation one would expect in raster functionality. As a side issue, would it be possible (is it foreseen?) to create raster operators that work in an equivalent arithmetic way as on single variable (i.e. 2*rast, rast ~ 128, rast < 3) but produce rast as output (maybe through a mapping to ST_MapAlgebra functions)? Any pointers welcome and excuses if I have overlooked discussions on this topic. Guido Lemoine Scientific Officer European Commission, Joint Research Centre (JRC) Institute for the Protection and Security of the Citizen (IPSC) Global Security and Crisis Management Unit Via E.Fermi 2749, I-21027 Ispra (VA) Italy, TP 268 Tel. +39 0332 786239 (direct line) Fax +39 0332 785154 e-mail: <mailto:[email protected]> [email protected] web: <http://globesec.jrc.ec.europa.eu/> http://globesec.jrc.ec.europa.eu
_______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
