Difference of NDVI using different sensors data: Sentinel-2, Landsat-OLI and Aster

[falahfakhri]

As I answered in the previous post,

@falahfakhri

I think it is not supported by SNAP, at the moment, but you could calibrate Aster in QGIS,

@Hddou

I did the calibrations with commercial programs

You mentioned in your previous post

@Hddou

I did not calibrate the images and did not apply any corrections.

So which one of your answer we could take in consideration to discuss, also, the main goal of your question was, your doubt bout the differences between NDVI results using different sensors data of the same AOI, and same time.

Please focus on the point of your demand.

Your original question,

@Hddou

I applied “SNAP NDVI processor” on raw satellite images of Sentinel-2, Landsat-Oli and Aster.
I found differences between the results, whereas, the images represent the same region and the same month.
I would like to know why