[GRASS-user] Extracting vegetation phenology from Landsat-based time series

Nikos Alexandris nik at nikosalexandris.net
Tue Nov 1 00:30:14 PDT 2016


* Veronica Andreo <veroandreo at gmail.com> [2016-10-31 10:40:33 +0100]:

>Hello Nikos and all :)
>
>Don't know exactly which parameters you would like to extract from your
>time series, Nikos, but if helpful, what I did was to use a combination of
>r.hants and temporal modules to get some phenological indicators such as,
>number of cycles per year,...

Vero,

Is the number of cycles per year in the Wiki as well?  Going through,
last time, I think I didn't grasp that.  Can you pin-point?  It's
exactly what we need at the moment.

Nikos

> ...yearly max and min values, dates of yearly max
>and min values, period that the variable was above a certain threshold, max
>rate of change (slope between every pair of maps and then aggregate per
>year with method=maximum). Some of those examples are in the wiki [0]. I
>believe that much more could be done with t.rast.algebra (it seems very
>powerfull), but I haven't yet tested enough.
>
>@Sajid, I agree it would be great to have such functionalities as
>"ready-to-use" module in GRASS, too. Therefore, we could avoid all the
>steps of moving a time series into r and then back again into GRASS [1]
>
>@MarkusM, local weighted regression sounds cool. +1 for that! It would be
>also very useful to have DINEOF [2] natively implemented. It is very nice
>when you want to keep the variation of the series instead of smoothing it
>out [1].
>
>Best,
>Vero
>
>[0] https://grasswiki.osgeo.org/wiki/Temporal_data_processing
>[1]
>https://grasswiki.osgeo.org/wiki/Temporal_data_processing/GRASS_R_raster_time_series_processing
>[2] http://modb.oce.ulg.ac.be/mediawiki/index.php/DINEOF

[rest deleted]


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