FIX: centering dates during S-G fitting, to avoid numerical issues caused by...

FIX: centering dates during S-G fitting, to avoid numerical issues caused by julian day values (10e8)

include/otbSavitzkyGolayVectorImageFunctor.h

@@ -257,7 +257,7 @@ public:
       for(unsigned int j = 0; j <= 2*m_Radius; ++j)
         {
         tmpInSeries[j] = gapfilledSeries[i+j-m_Radius];
-        tmpDates[j] = m_Dates[i+j-m_Radius];
+        tmpDates[j] = m_Dates[i+j-m_Radius] - m_Dates[i+m_Radius]; // centering dates to avoid numerical issues caused by julian day values (10e8)
         }
 
       // Polynomial fitting over (X,Y)=(tmpdates, tmpInSeries)