Here's a step-by-step tutorial on the Zonal Statistics plugin http://www.qgistutorials.com/en/docs/sampling_raster_data.html You can use a custom field prefix for each of the rasters and you will have columns representing stats for each of the year.
-Ujaval On 06-Oct-2015 1:13 am, "Michael Treglia" <[email protected]> wrote: > Hi Sam, > > Important point of clarification: Do you want all of the individual pixel > values? Or aggregate statistics, like min/max/mean/med...? > > For the latter, there are a few tools you can use. I typically use a tool > in the Processing Toolbox, implemented in SAGA: Go to Processing Toolbox - > > SAGA -> Shape-Grid -> Grid Statistics and you'll be able to get those > stats for your desired grids. The only downside, if i recall correctly, is > that the column names don't necessarily indicate which layer the stats are > from, if you're operating on multiple rasters at a time. There's a 'Zonal > Statistics' tool also, which I think works well too. It is a plugin - it > is a 'core plugin', which means it come with QGIS,though you might need to > activate it (can't remember). If it is already activated, you'll see it > when you go to the 'Raster' toolbar menu. If you don't see it there, you > can search for it in the 'Plugin' dialogue and make sure the box next to it > is checked. > > (more details on plugins here: > https://docs.qgis.org/2.8/en/docs/user_manual/plugins/plugins.html) > > If you want the former, that might be a bit more complicated, and is > something I typically do directly in R, but could give advice here too. > > hope that helps! > mike > > On Mon, Oct 5, 2015 at 1:39 PM, Sam Almond <[email protected]> wrote: > >> Dear QGIS Users, >> >> >> >> I am new to using qGIS and can’t find an obvious solution to my problem. >> >> >> >> I have created a time series of NDVI rasters covering my area of >> interest. The NDVI time series is derived from the Landsat imagery spanning >> a decade of so. I also have a created a vector layer, consisting of >> polygons, which represents digitized farmed fields (70 or so). The plan is >> to use the polygons to extract the raster values from the time series, >> ideally one year at a time. The ideal scenario is to be provided with the >> pixel values per field (polygon) per NDVI over the year. Is this possible? >> Help appreciated. >> >> >> Many thanks >> >> >> Sam >> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> > > > _______________________________________________ > Qgis-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-user >
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