I have been using QGIS with Sentinel2A imagery, and i just noticed something wierd to the extent of my knowledge which should have an explanation.
Consider the 3 bands of Sentinel2, 4,3,2 that are the Red, Green and Blue ones and the following steps:
- Lets make an RGB composite raster with QGIS GDAL Merge tool with the 3 full bands from the Sentinel imagery.
- Now crop the RGB output image to the extent of the desired region of interest (ROI) with GDAL Clip Raster by mask layer, inserting the ROI polygon and saving the output: "clippedFromWholeNDVI.tif" (default options are left intact).
- Now lets crop the 3 Sentinel bands to the extent of the ROI and then construct in the same way the RGB composite.
The results are different in regard to their values and visually.
Can you explain why this happens?