Update README.md

README.md

@@ -18,7 +18,7 @@ It contains 2,433 patches within the French metropolitan territory with panoptic
 Each patch is a Sentinel-2 multispectral image time series of variable lentgh. 
 
 This dataset have been extended in 2021 with aligned radar Sentinel-1 observations for all 2433 patches.  
-For each patch, it constains approximately 70 observations of Sentinel-1 in ascending orbit, and 70 observations in descending orbit. This extension is named PASTIS-R.
+For each patch, it constains approximately 70 observations of Sentinel-1 in ascending orbit, and 70 observations in descending orbit. Each each Sentinel1 observation is assembled into a 3-channel image: vertical polarization (VV), horizontal polarisation (VH), and the ratio vertical over horizontal polarization (VV/VH). This extension is named PASTIS-R.
 
 We extend PASTIS with aligned very high resolution satellite images from SPOT 6-7 constellation for all 2433 patches in addition to the Sentinel-1 and 2 time series. 
 The image are resampled to a 1m resolution and converted to 8 bits.