Compare NDVI Extracted from Landsat 8 Imagery with that from Landsat 7 Imagery

Abstract

Landsat 8, the ongoing mission of the Landsat satellites that have provided over 40 years of images, continues to benefit long-term research. However, it is important to know if the spectral features of Landsat 8 are of the same standard as previous Landsat imagery because Landsat 8 images have narrower bands, especially because of the normalized difference vegetation index (NDVI) calculation which is the most popular vegetation index. In this study NDVI values derived from Landsat 8 images were compared with those calculated from Landsat 7 and ground measured hyperspectral data. The result shows that Landsat 8 NDVI is larger than Landsat 7 NDVI in lower vegetation covered areas and the difference becomes smaller as the value of NDVI increases. This indicates that NDVI of Landsat 7 and Landsat 8 is consistent when dealing with high vegetation covered areas (e.g. forest area and tall grass prairie) because the difference between Landsat 7 and 8 NDVI is close to zero when the value of NDVI is high, but this needs to be further investigated. There is also further need for calibration of NDVI in low vegetation covered areas in order to achieve consistency between Landsat 7 and Landsat 8 images.