[R] Filtering Time Series / apply STL method

Jan Verbesselt Jan.Verbesselt at agr.kuleuven.ac.be
Wed Aug 6 11:46:57 CEST 2003

Dear R Helpers,

Which technique can I apply to get the noise out of the following graph?
The data displayed shows the seasonal variation of NDVI (vegetation
photosynthesis) extracted from the VEGETATION satellite sensor.  It
contains big errors caused by cloud cover, which gives very low values
in the time series (=> outliers have to be deleted).  Are there certain
smoothing or filtering techniques I could use? I tested the Holt-winters
filtering and the kernel smoothing technique but none of these give
sufficient results. 


Ps: Thanks for the previous answer: setting the dim(Timeserie) <- NULL
was the solution. The aim is to apply the STL function on these results
because at the moment STL runs but results are not logical.

Jan Verbesselt 
Research Associate 
Lab of Geomatics and Forest Engineering K.U. Leuven
Vital Decosterstraat 102. B-3000 Leuven Belgium 
Fax: +32-16-329760

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