Thanks Markus, Will try it soon.
Sajid On Mon, Nov 28, 2016 at 9:03 AM, Markus Metz <[email protected]> wrote: > There is a new addon r.seasons which determines the number of seasons per > pixel and extracts start and end dates for the given number of seasons from > a time series. > > The module is designed for noisy input, e.g. > > time|value > 0|0 > 1|0 > 2|1 > 3|0 > 4|1 > 5|1 > 6|1 > 7|0 > 8|1 > 9|1 > 10|1 > 11|1 > 12|0 > 13|0 > > with threshold 0.5 and minimum season length set to 3 would detect one > season. Core season start is at 4, end at 10. Full season start is at 2, > end at 10. > > Markus M > > > On Wed, Nov 9, 2016 at 4:17 PM, Nikos Alexandris <[email protected]> > wrote: > >> Nikos Alexandris: >> >> 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. >>>>> >>>> >> Veronica Andreo: >> >> Yes, maybe it is not well explained, but it is here: >>>> https://grasswiki.osgeo.org/wiki/Temporal_data_processing#Fi >>>> lling_and_reconstructing_time_series_data_with_gaps_-_HANTS >>>> >>> >> and also in the manual under "NOTES" >>>> https://grass.osgeo.org/grass70/manuals/addons/r.hants.html >>>> >>> >> The idea is, once you are happy with the result of hants, you ask for >>>> amplitude outputs and with those amplitude maps (you'll have one map per >>>> frequency) you run r.series method=max_raster. This will give you the >>>> most >>>> important frequency (according to amplitude value of that frequency) in >>>> each pixel. If the result is that the most important frequency is 0, >>>> then >>>> you have one cycle per year (that, if you use a base period of one year >>>> of >>>> course). >>>> >>> >> Hope it is clearer now :) >>>> >>> >> Nikos: >> >> Yes. It was even before -- just me read through quickly. >>> >>> r.hants is awesome! >>> >>> We have 24 Landsat 8 derived EVI2 maps (2 for each month) for one year. >>> Clouds and Water surfaces removed. Another set of "relatively normalised >>> images, using `i.histo.match` is also ready. We really need to "fix" >>> `i.histo.match` to crunch floats directly. The resulting ranges worry >>> me a bit -- I just followed the "old" way as discussed some years ago in >>> a relevant thread (floats > integers > histo-matching > floats). >>> >>> Anyhow, I am testing the following: >>> >>> for NF in 4 5 6 7 8 ;do r.hants file=evi2_maps nf=$NF fet=0.05 dod=3 >>> base_period=24 suffix=_hants_nf_$NF amplitude=amplitude_hants_nf_$NF >>> phase=phase_hants_nf_$NF ;done >>> >>> (thinking loudly... it would be super-nice to have `t.rast.hants`) >>> >>> Not sure about `dod`. Perhaps it should also follow a patten like 3 4 5 >>> 6 and 7 for the above? >>> >>> for NF in 5 6 7 8 ; do t.rast.series evi2_hants_nf_$NF method=max_raster >>> output=dominant_frequencies_hants_nf_$NF --o >>> >> >> Just in case, the above *should* read: >> >> for NF in 4 5 6 7 8 ;do r.series input=`g.list rast >> pattern=amplitude*nf_${NF}* separator=comma` method=max_raster >> output=dominant_frequencies_hants_nf_${NF} --o ;done >> >> >> "Dominant" frequencies 0, 1, 2 and 3 appear to be within the areas >>> of our interest (agricultural surfaces). Very good. And convincing. >>> Yet I am learning to interpret this correctly. And the "phase" as well. >>> Reminds math studies, years ago. >>> >> >> It is a "good" thing to actually have similar dominant frequency "maps" >> for all of the experimented Number of Frequencies. >> >> A confirmation would be reassuring. >> >> Thanks, Nikos >> >> [rest deleted] >> >> _______________________________________________ >> grass-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/grass-user >> > >
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