Assessing Radiometric Correction Approaches for Multi-Spectral UAS Imagery for Horticultural Applications

Abstract

UAS-based multi-spectral imagery is becoming increasingly popular for the improved monitoring and managing of various horticultural crops. However, for UAS data to be used as an industry standard for assessing tree structure and condition as well as production parameters, it is imperative that the appropriate data collection and pre-processing protocols are established to enable multi-temporal comparison. There are several UAS-based radiometric correction methods commonly used for precision agricultural purposes. However, their relative accuracies have not been assessed for data acquired in complex horticultural environments. This study assessed the variations in estimated surface reflectance values of different radiometric corrections applied to multi-spectral UAS imagery acquired in both avocado and banana orchards. We found that inaccurate calibration panel measurements, inaccurate signal-to-reflectance conversion, and high variation in geometry between illumination, surface, and sensor viewing produced significant radiometric variations in at-surface reflectance estimates. Potential solutions to address these limitations included appropriate panel deployment, site-specific sensor calibration, and appropriate BRDF correction. Future UAS based horticultural crop monitoring can benefit from the proposed solutions to radiometric corrections to ensure they are using comparable image-based maps of multi-temporal biophysical properties.

Plant phenotyping relevance

果樹園のUASマルチスペクトル画像に対する放射補正手法を比較・評価し、樹体構造・状態や生産関連パラメータの測定に必要な校正条件を検討しているため、画像ベース植物フェノタイピング手法が中心です。

Code and data availability

The paper describes in-house Python scripts for irradiance normalisation, BRDF correction, and zonal statistics, but no public deposit, availability statement, or authors' URL for these scripts or the avocado/banana UAS image datasets is provided. All allowed URLs are the article itself, its license/repository record,或

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