Reduced Prediction Saturation and View Effects for Estimating the Leaf Area Index of Winter Wheat

Relationships between vegetation indices (VIs) and leaf area index (LAI) tend to saturate in the nadir direction, and vary with crop canopy structure and view zenith angles (VZAs). The objective of this paper was to improve the monitoring accuracy and angular stability of VIs for estimating LAI usin...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on geoscience and remote sensing 2019-03, Vol.57 (3), p.1637-1652
Main Authors: He, Li, Coburn, Craig A., Wang, Zhi-Jie, Feng, Wei, Guo, Tian-Cai
Format: Article
Language:English
Subjects:
Agriculture
Algorithms
Angle sensitivity
Calibration
Canopies
Canopy
Direction
Estimation
Exploitation
Indexes
Leaf area
Leaf area index
leaf area index (LAI)
monitoring model
multiangular hyperspectral reflectance
Reflectance
Remote sensing
Satellites
Saturation
saturation factor (SF)
Sensitivity
Soil
Specificity
Spectral reflectance
Stability
Vegetation mapping
View effects
Wheat
Winter wheat
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Relationships between vegetation indices (VIs) and leaf area index (LAI) tend to saturate in the nadir direction, and vary with crop canopy structure and view zenith angles (VZAs). The objective of this paper was to improve the monitoring accuracy and angular stability of VIs for estimating LAI using multiangular remote sensing data. The relationship between LAI and ground-based hyperspectral spectral reflectance was quantified in winter wheat (Triticum aestivum L.) exhibiting erectophile and planophile growth habits. To further reduce the saturation, species specificity, and angular sensitivity, we developed a saturation factor (SF), based on near-infrared and green bands. Multiplying all VIs by SF greatly improved the association with LAI across all VZAs ( R^{2} = 0.73{-}0.82 ). Most VI \times SF values, particularly optimized soil-adjusted VI \times SF, were able to construct universal algorithms across VZAs for accurate estimation of LAI due to the sensitivity of SF to LAI in a dense canopy, and the insensitivity of SF to view effects with larger VZAs. This approach is also promising for the exploitation of multiangular satellite data for the design and calibration of nonview-angle-corrected spectral reflectance, for which the sensor is only deployed at fixed observation direction.
ISSN:0196-2892
1558-0644
DOI:10.1109/TGRS.2018.2868138