TY - JOUR
T1 - Vegetation Indices Combining the Red and Red-Edge Spectral Information for Leaf Area Index Retrieval
AU - Xie, Qiaoyun
AU - Dash, Jadu
AU - Huang, Wenjiang
AU - Peng, Dailiang
AU - Qin, Qiming
AU - Mortimer, Hugh
AU - Casa, Raffaele
AU - Pignatti, Stefano
AU - Laneve, Giovanni
AU - Pascucci, Simone
AU - Dong, Yingying
AU - Ye, Huichun
N1 - Publisher Copyright:
© 2018 Institute of Electrical and Electronics Engineers. All rights reserved.
PY - 2018/5
Y1 - 2018/5
N2 - Leaf area index (LAI) is a crucial biophysical variable for agroecosystems monitoring. Conventional vegetation indices (VIs) based on red and near infrared regions of the electromagnetic spectrum, such as the normalized difference vegetation index (NDVI), are commonly used to estimate the LAI. However, these indices commonly saturate at moderate-to-dense canopies (e.g., NDVI saturates when LAI exceeds three). Modified VIs have then been proposed to replace the typical red/green spectral region with the red-edge spectral region. One significant and often ignored aspect of this modification is that the reflectance in the red-edge spectral region is comparatively sensitive to chlorophyll content which is highly variable between different crops and different phenological states. In this study, three improved indices are proposed combining reflectance both in the red and red-edge spectral regions into the NDVI, the modified simple ratio index (MSR), and the green chlorophyll index (CIgreen) formula. These improved indices are termed NDVIred-RE (red and red-edge NDVI),MSRred-RE (red and red-edgeMSR index), and CIred-RE (red and red-edgeCI). The indices were tested using RapidEye images and in-situ data from campaigns at Maccarese Farm (Central Rome, Italy), in which four crop types at four different growth stages were measured.We investigated the predictive power of nine VIs for crop LAI estimation, including NDVI, MSR, and CIgreen; the red-edge modified indices: NDVIRed-edge, MSRRed-edge, and CIRed-edge (generally represented by VIRed-edge); and the newly improved indices: NDVIred-RE, MSRred-RE, andCIred-RE (generally represented byVIred-RE). The results show that VIred-RE improves the coefficient of determination (R2) for LAI estimation by 10% in comparison to VIRed-edge. The newly improved indices prove to be the powerful alternatives for the LAI estimation of crops with wide chlorophyll range, and may provide valuable information for satellites equipped with red-edge channels (such as Sentinel-2) when applied to precision agriculture.
AB - Leaf area index (LAI) is a crucial biophysical variable for agroecosystems monitoring. Conventional vegetation indices (VIs) based on red and near infrared regions of the electromagnetic spectrum, such as the normalized difference vegetation index (NDVI), are commonly used to estimate the LAI. However, these indices commonly saturate at moderate-to-dense canopies (e.g., NDVI saturates when LAI exceeds three). Modified VIs have then been proposed to replace the typical red/green spectral region with the red-edge spectral region. One significant and often ignored aspect of this modification is that the reflectance in the red-edge spectral region is comparatively sensitive to chlorophyll content which is highly variable between different crops and different phenological states. In this study, three improved indices are proposed combining reflectance both in the red and red-edge spectral regions into the NDVI, the modified simple ratio index (MSR), and the green chlorophyll index (CIgreen) formula. These improved indices are termed NDVIred-RE (red and red-edge NDVI),MSRred-RE (red and red-edgeMSR index), and CIred-RE (red and red-edgeCI). The indices were tested using RapidEye images and in-situ data from campaigns at Maccarese Farm (Central Rome, Italy), in which four crop types at four different growth stages were measured.We investigated the predictive power of nine VIs for crop LAI estimation, including NDVI, MSR, and CIgreen; the red-edge modified indices: NDVIRed-edge, MSRRed-edge, and CIRed-edge (generally represented by VIRed-edge); and the newly improved indices: NDVIred-RE, MSRred-RE, andCIred-RE (generally represented byVIred-RE). The results show that VIred-RE improves the coefficient of determination (R2) for LAI estimation by 10% in comparison to VIRed-edge. The newly improved indices prove to be the powerful alternatives for the LAI estimation of crops with wide chlorophyll range, and may provide valuable information for satellites equipped with red-edge channels (such as Sentinel-2) when applied to precision agriculture.
KW - Precision agriculture
KW - RapidEye
KW - remote sensing
KW - vegetation index (VI)
UR - http://www.scopus.com/inward/record.url?scp=85044737660&partnerID=8YFLogxK
U2 - 10.1109/JSTARS.2018.2813281
DO - 10.1109/JSTARS.2018.2813281
M3 - Article
SN - 1939-1404
VL - 11
SP - 1482
EP - 1492
JO - IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
JF - IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
IS - 5
ER -