Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models

The outdoor spectral detection of winter jujube quality is affected by complex ambient light and surface heterogeneity, resulting in limited inversion accuracy. To address this problem, this study proposes a correction method for outdoor spectral inversion based on the bidirectional polarization ref...

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Main Authors: Yabei Di, Jinlong Yu, Huaping Luo, Huaiyu Liu, Lei Kang, Yuesen Tong
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Agriculture
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Online Access:https://www.mdpi.com/2077-0472/15/13/1334
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author Yabei Di
Jinlong Yu
Huaping Luo
Huaiyu Liu
Lei Kang
Yuesen Tong
author_facet Yabei Di
Jinlong Yu
Huaping Luo
Huaiyu Liu
Lei Kang
Yuesen Tong
author_sort Yabei Di
collection DOAJ
description The outdoor spectral detection of winter jujube quality is affected by complex ambient light and surface heterogeneity, resulting in limited inversion accuracy. To address this problem, this study proposes a correction method for outdoor spectral inversion based on the bidirectional polarization reflectance distribution function (BPDF) model. It was used to enhance the detection accuracy of water content and soluble solid (SSC) content of winter jujube. Experimentally, 900–1750 nm hyperspectral data of ripe winter jujube samples were collected at non-polarization and 0°, 45°, 90°, and 135° polarization azimuths. The spectra were inverted using four semi-empirical BPDF models, Nadal–Breon, Litvinov, Maignan and Xie–Cheng, and the corrected spectra were obtained by mean fusion. The quality prediction models are subsequently combined with the competitive adaptive reweighting algorithm (CARS) and partial least squares (PLS). The results showed that the modified spectra significantly optimized the prediction performance. The prediction set correlation coefficients (Rp) of the water content and SSC models were improved by 10–30% compared with the original spectra. The percentage of models with RPIQ values greater than 2 increased from 40% to 60%. Among them, the Litvinov model performs outstandingly in the direction of no polarization and 135° polarization, with the highest Rp of 0.8829 for water content prediction and RPIQ of 2.54. The Xie–Cheng model has an RPIQ of 2.64 for SSC prediction at 90° polarization, which shows the advantage of sensitivity to the deeper constituents. The different models complemented each other in multi-polarization scenarios. The Nadal–Breon model was suitable for epidermal reflection-dominated scenarios, and the Maignan model efficiently coupled epidermal and internal moisture characteristics through the moisture sensitivity index. The study verifies the effectiveness of the spectral correction method based on the BPDF model for outdoor quality detection of winter jujube, which provides a new path for the spectral detection of agricultural products in complex environments. In the future, it is necessary to further optimize the dynamic adjustment mechanism of the model parameters and improve the ability of environmental interference correction by combining multi-source data fusion.
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series Agriculture
spelling doaj-art-cd1daba67dfe485881ed647d2294f65e2025-08-20T03:16:47ZengMDPI AGAgriculture2077-04722025-06-011513133410.3390/agriculture15131334Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF ModelsYabei Di0Jinlong Yu1Huaping Luo2Huaiyu Liu3Lei Kang4Yuesen Tong5College of Mechanical and Electrical Engineering, Tarim University, Alar 843300, ChinaCollege of Mechanical and Electrical Engineering, Tarim University, Alar 843300, ChinaCollege of Mechanical and Electrical Engineering, Tarim University, Alar 843300, ChinaCollege of Mechanical and Electrical Engineering, Tarim University, Alar 843300, ChinaCollege of Mechanical and Electrical Engineering, Tarim University, Alar 843300, ChinaCollege of Mechanical and Electrical Engineering, Tarim University, Alar 843300, ChinaThe outdoor spectral detection of winter jujube quality is affected by complex ambient light and surface heterogeneity, resulting in limited inversion accuracy. To address this problem, this study proposes a correction method for outdoor spectral inversion based on the bidirectional polarization reflectance distribution function (BPDF) model. It was used to enhance the detection accuracy of water content and soluble solid (SSC) content of winter jujube. Experimentally, 900–1750 nm hyperspectral data of ripe winter jujube samples were collected at non-polarization and 0°, 45°, 90°, and 135° polarization azimuths. The spectra were inverted using four semi-empirical BPDF models, Nadal–Breon, Litvinov, Maignan and Xie–Cheng, and the corrected spectra were obtained by mean fusion. The quality prediction models are subsequently combined with the competitive adaptive reweighting algorithm (CARS) and partial least squares (PLS). The results showed that the modified spectra significantly optimized the prediction performance. The prediction set correlation coefficients (Rp) of the water content and SSC models were improved by 10–30% compared with the original spectra. The percentage of models with RPIQ values greater than 2 increased from 40% to 60%. Among them, the Litvinov model performs outstandingly in the direction of no polarization and 135° polarization, with the highest Rp of 0.8829 for water content prediction and RPIQ of 2.54. The Xie–Cheng model has an RPIQ of 2.64 for SSC prediction at 90° polarization, which shows the advantage of sensitivity to the deeper constituents. The different models complemented each other in multi-polarization scenarios. The Nadal–Breon model was suitable for epidermal reflection-dominated scenarios, and the Maignan model efficiently coupled epidermal and internal moisture characteristics through the moisture sensitivity index. The study verifies the effectiveness of the spectral correction method based on the BPDF model for outdoor quality detection of winter jujube, which provides a new path for the spectral detection of agricultural products in complex environments. In the future, it is necessary to further optimize the dynamic adjustment mechanism of the model parameters and improve the ability of environmental interference correction by combining multi-source data fusion.https://www.mdpi.com/2077-0472/15/13/1334BPDF modelshyperspectral imagingspectral inversionspectral correctionquality detection
spellingShingle Yabei Di
Jinlong Yu
Huaping Luo
Huaiyu Liu
Lei Kang
Yuesen Tong
Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models
Agriculture
BPDF models
hyperspectral imaging
spectral inversion
spectral correction
quality detection
title Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models
title_full Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models
title_fullStr Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models
title_full_unstemmed Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models
title_short Study on Outdoor Spectral Inversion of Winter Jujube Based on BPDF Models
title_sort study on outdoor spectral inversion of winter jujube based on bpdf models
topic BPDF models
hyperspectral imaging
spectral inversion
spectral correction
quality detection
url https://www.mdpi.com/2077-0472/15/13/1334
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AT huapingluo studyonoutdoorspectralinversionofwinterjujubebasedonbpdfmodels
AT huaiyuliu studyonoutdoorspectralinversionofwinterjujubebasedonbpdfmodels
AT leikang studyonoutdoorspectralinversionofwinterjujubebasedonbpdfmodels
AT yuesentong studyonoutdoorspectralinversionofwinterjujubebasedonbpdfmodels