I want to perform PCA on 2 sheets of Landsat imagery with different acquisition time and coordinates. Prior to processing, should I combine both into one scene (mosaicking process)? If so, how is the procedure pre-processing. Is it possible I could process them separately?
I assume that you have good reasons for using PCA instead of, e.g., Tasseled cap.
PCA is very sensitive to the scene (that's why it is not used a lot), so you won't get the same result if you work on the mosaic than if you work on each scene separately. I would clearly avoid woring on a mosaic if your images correspond to different seasons. If you have the same season, I can't tell which is the best (mosaicking/not mosaicking).However, if you do mosaicking, then I recommend atmospheric.