Principal components
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When principal components analysis (PCA) is used for change detection, the input bands are acquired at different dates. The first principal component refers to invariant information while second principal component shows the magnitude of change of dynamic components. To simplify the interpretation only three bands (Band 3 (red), 4 (NIR) and 5 (SWIR) ) of two different dates (1992 and 2005) are used.
