Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning

Alfalfa is a valuable and intensively produced forage crop in the United States, and the timely estimation of its yield can inform precision management decisions. However, traditional yield assessment approaches are laborious and time-consuming, and thus hinder the acquisition of timely information...

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Main Authors: Luwei Feng, Zhou Zhang, Yuchi Ma, Qingyun Du, Parker Williams, Jessica Drewry, Brian Luck
Format: Article
Language:English
Published: MDPI AG 2020-06-01
Series:Remote Sensing
Subjects:
Online Access:https://www.mdpi.com/2072-4292/12/12/2028
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spelling doaj-a2027643cec24f5bb976f0551c87c40e2020-11-25T03:37:02ZengMDPI AGRemote Sensing2072-42922020-06-01122028202810.3390/rs12122028Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble LearningLuwei Feng0Zhou Zhang1Yuchi Ma2Qingyun Du3Parker Williams4Jessica Drewry5Brian Luck6Biological Systems Engineering, University of Wisconsin–Madison, Madison, WI 53706, USABiological Systems Engineering, University of Wisconsin–Madison, Madison, WI 53706, USABiological Systems Engineering, University of Wisconsin–Madison, Madison, WI 53706, USASchool of Resources and Environmental Science, Wuhan University, Wuhan 430079, ChinaBiological Systems Engineering, University of Wisconsin–Madison, Madison, WI 53706, USABiological Systems Engineering, University of Wisconsin–Madison, Madison, WI 53706, USABiological Systems Engineering, University of Wisconsin–Madison, Madison, WI 53706, USAAlfalfa is a valuable and intensively produced forage crop in the United States, and the timely estimation of its yield can inform precision management decisions. However, traditional yield assessment approaches are laborious and time-consuming, and thus hinder the acquisition of timely information at the field scale. Recently, unmanned aerial vehicles (UAVs) have gained significant attention in precision agriculture due to their efficiency in data acquisition. In addition, compared with other imaging modalities, hyperspectral data can offer higher spectral fidelity for constructing narrow-band vegetation indices which are of great importance in yield modeling. In this study, we performed an in-season alfalfa yield prediction using UAV-based hyperspectral images. Specifically, we firstly extracted a large number of hyperspectral indices from the original data and performed a feature selection to reduce the data dimensionality. Then, an ensemble machine learning model was developed by combining three widely used base learners including random forest (RF), support vector regression (SVR) and K-nearest neighbors (KNN). The model performance was evaluated on experimental fields in Wisconsin. Our results showed that the ensemble model outperformed all the base learners and a coefficient of determination (R<sup>2</sup>) of 0.874 was achieved when using the selected features. In addition, we also evaluated the model adaptability on different machinery compaction treatments, and the results further demonstrate the efficacy of the proposed ensemble model.https://www.mdpi.com/2072-4292/12/12/2028alfalfayield predictionhyperspectralunmanned aerial vehicle (UAV)ensemble learningvegetation index
collection DOAJ
language English
format Article
sources DOAJ
author Luwei Feng
Zhou Zhang
Yuchi Ma
Qingyun Du
Parker Williams
Jessica Drewry
Brian Luck
spellingShingle Luwei Feng
Zhou Zhang
Yuchi Ma
Qingyun Du
Parker Williams
Jessica Drewry
Brian Luck
Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning
Remote Sensing
alfalfa
yield prediction
hyperspectral
unmanned aerial vehicle (UAV)
ensemble learning
vegetation index
author_facet Luwei Feng
Zhou Zhang
Yuchi Ma
Qingyun Du
Parker Williams
Jessica Drewry
Brian Luck
author_sort Luwei Feng
title Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning
title_short Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning
title_full Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning
title_fullStr Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning
title_full_unstemmed Alfalfa Yield Prediction Using UAV-Based Hyperspectral Imagery and Ensemble Learning
title_sort alfalfa yield prediction using uav-based hyperspectral imagery and ensemble learning
publisher MDPI AG
series Remote Sensing
issn 2072-4292
publishDate 2020-06-01
description Alfalfa is a valuable and intensively produced forage crop in the United States, and the timely estimation of its yield can inform precision management decisions. However, traditional yield assessment approaches are laborious and time-consuming, and thus hinder the acquisition of timely information at the field scale. Recently, unmanned aerial vehicles (UAVs) have gained significant attention in precision agriculture due to their efficiency in data acquisition. In addition, compared with other imaging modalities, hyperspectral data can offer higher spectral fidelity for constructing narrow-band vegetation indices which are of great importance in yield modeling. In this study, we performed an in-season alfalfa yield prediction using UAV-based hyperspectral images. Specifically, we firstly extracted a large number of hyperspectral indices from the original data and performed a feature selection to reduce the data dimensionality. Then, an ensemble machine learning model was developed by combining three widely used base learners including random forest (RF), support vector regression (SVR) and K-nearest neighbors (KNN). The model performance was evaluated on experimental fields in Wisconsin. Our results showed that the ensemble model outperformed all the base learners and a coefficient of determination (R<sup>2</sup>) of 0.874 was achieved when using the selected features. In addition, we also evaluated the model adaptability on different machinery compaction treatments, and the results further demonstrate the efficacy of the proposed ensemble model.
topic alfalfa
yield prediction
hyperspectral
unmanned aerial vehicle (UAV)
ensemble learning
vegetation index
url https://www.mdpi.com/2072-4292/12/12/2028
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