Review

Korean J. Remote Sens. 2024; 40(4): 319-341

Published online: August 31, 2024

https://doi.org/10.7780/kjrs.2024.40.4.1

© Korean Society of Remote Sensing

Effects of Environmental Conditions on Vegetation Indices from Multispectral Images: A Review

Md Asrakul Haque1, Md Nasim Reza2,3, Mohammod Ali2,3, Md Rejaul Karim1, Shahriar Ahmed1, Kyung-Do Lee4, Young Ho Khang5, Sun-Ok Chung6,7*

1PhD Student, Department of Agricultural Machinery Engineering, Chungnam National University, Daejeon, Republic of Korea
2Postdoctoral Researcher, Department of Agricultural Machinery Engineering, Chungnam National University, Daejeon, Republic of Korea
3Postdoctoral Researcher, Department of Smart Agricultural Systems, Chungnam National University, Daejeon, Republic of Korea
4Senior Researcher, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Republic of Korea
5Researcher, Jeollabukdo Agriculture Research and Extension Services, Iksan, Republic of Korea
6Professor, Department of Agricultural Machinery Engineering, Chungnam National University, Daejeon, Republic of Korea
7Professor, Department of Smart Agricultural Systems, Chungnam National University, Daejeon, Republic of Korea

Correspondence to : Sun-Ok Chung
E-mail: sochung@cnu.ac.kr

Received: July 31, 2024; Revised: August 16, 2024; Accepted: August 26, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The utilization of multispectral imaging systems (MIS) in remote sensing has become crucial for large-scale agricultural operations, particularly for diagnosing plant health, monitoring crop growth, and estimating plant phenotypic traits through vegetation indices (VIs). However, environmental factors can significantly affect the accuracy of multispectral reflectance data, leading to potential errors in VIs and crop status assessments. This paper reviewed the complex interactions between environmental conditions and multispectral sensors emphasizing the importance of accounting for these factors to enhance the reliability of reflectance data in agricultural applications. An overview of the fundamentals of multispectral sensors and the operational principles behind vegetation index (VI) computation was reviewed. The review highlights the impact of environmental conditions, particularly solar zenith angle (SZA), on reflectance data quality. Higher SZA values increase cloud optical thickness and droplet concentration by 40–70%, affecting reflectance in the red (–0.01 to 0.02) and near-infrared (NIR) bands (–0.03 to 0.06), crucial for VI accuracy. An SZA of 45° is optimal for data collection, while atmospheric conditions, such as water vapor and aerosols, greatly influence reflectance data, affecting forest biomass estimates and agricultural assessments. During the COVID-19 lockdown, reduced atmospheric interference improved the accuracy of satellite image reflectance consistency. The NIR/Red edge ratio and water index emerged as the most stable indices, providing consistent measurements across different lighting conditions. Additionally, a simulated environment demonstrated that MIS surface reflectance can vary 10–20% with changes in aerosol optical thickness, 15–30% with water vapor levels, and up to 25% in NIR reflectance due to high wind speeds. Seasonal factors like temperature and humidity can cause up to a 15% change, highlighting the complexity of environmental impacts on remote sensing data. This review indicated the importance of precisely managing environmental factors to maintain the integrity of VIs calculations. Explaining the relationship between environmental variables and multispectral sensors offers valuable insights for optimizing the accuracy and reliability of remote sensing data in various agricultural applications.

Keywords Remote sensing, Multispectral sensors, Environmental effects, Spectral resolution, Sensor calibration, Vegetation indices

Review

Korean J. Remote Sens. 2024; 40(4): 319-341

Published online August 31, 2024 https://doi.org/10.7780/kjrs.2024.40.4.1

Copyright © Korean Society of Remote Sensing.

Effects of Environmental Conditions on Vegetation Indices from Multispectral Images: A Review

Md Asrakul Haque1, Md Nasim Reza2,3, Mohammod Ali2,3, Md Rejaul Karim1, Shahriar Ahmed1, Kyung-Do Lee4, Young Ho Khang5, Sun-Ok Chung6,7*

1PhD Student, Department of Agricultural Machinery Engineering, Chungnam National University, Daejeon, Republic of Korea
2Postdoctoral Researcher, Department of Agricultural Machinery Engineering, Chungnam National University, Daejeon, Republic of Korea
3Postdoctoral Researcher, Department of Smart Agricultural Systems, Chungnam National University, Daejeon, Republic of Korea
4Senior Researcher, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Republic of Korea
5Researcher, Jeollabukdo Agriculture Research and Extension Services, Iksan, Republic of Korea
6Professor, Department of Agricultural Machinery Engineering, Chungnam National University, Daejeon, Republic of Korea
7Professor, Department of Smart Agricultural Systems, Chungnam National University, Daejeon, Republic of Korea

Correspondence to:Sun-Ok Chung
E-mail: sochung@cnu.ac.kr

Received: July 31, 2024; Revised: August 16, 2024; Accepted: August 26, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The utilization of multispectral imaging systems (MIS) in remote sensing has become crucial for large-scale agricultural operations, particularly for diagnosing plant health, monitoring crop growth, and estimating plant phenotypic traits through vegetation indices (VIs). However, environmental factors can significantly affect the accuracy of multispectral reflectance data, leading to potential errors in VIs and crop status assessments. This paper reviewed the complex interactions between environmental conditions and multispectral sensors emphasizing the importance of accounting for these factors to enhance the reliability of reflectance data in agricultural applications. An overview of the fundamentals of multispectral sensors and the operational principles behind vegetation index (VI) computation was reviewed. The review highlights the impact of environmental conditions, particularly solar zenith angle (SZA), on reflectance data quality. Higher SZA values increase cloud optical thickness and droplet concentration by 40–70%, affecting reflectance in the red (–0.01 to 0.02) and near-infrared (NIR) bands (–0.03 to 0.06), crucial for VI accuracy. An SZA of 45° is optimal for data collection, while atmospheric conditions, such as water vapor and aerosols, greatly influence reflectance data, affecting forest biomass estimates and agricultural assessments. During the COVID-19 lockdown, reduced atmospheric interference improved the accuracy of satellite image reflectance consistency. The NIR/Red edge ratio and water index emerged as the most stable indices, providing consistent measurements across different lighting conditions. Additionally, a simulated environment demonstrated that MIS surface reflectance can vary 10–20% with changes in aerosol optical thickness, 15–30% with water vapor levels, and up to 25% in NIR reflectance due to high wind speeds. Seasonal factors like temperature and humidity can cause up to a 15% change, highlighting the complexity of environmental impacts on remote sensing data. This review indicated the importance of precisely managing environmental factors to maintain the integrity of VIs calculations. Explaining the relationship between environmental variables and multispectral sensors offers valuable insights for optimizing the accuracy and reliability of remote sensing data in various agricultural applications.

Keywords: Remote sensing, Multispectral sensors, Environmental effects, Spectral resolution, Sensor calibration, Vegetation indices

KSRS
August 2024 Vol. 40, No.4, pp. 319-418

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