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A Fixed Low-Cost NIR-Modified RGB Camera for Spatio-Temporal Relative Monitoring under Simulated Agrivoltaic Shading

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2026 ASABE Annual International Meeting  2601556.(doi:10.13031/aim.202601556)
Authors:   Pierluigi Rossi, Dr., Giorgia Di Domenico, Dr., Massimo Cecchini, Prof., Andrea Colantoni, Prof.
Keywords:   agrivoltaics, fixed proximal sensing, qualitative monitoring, low-cost imaging, NIR-modified RGB camera, relative NDVI, shading heterogeneity.

Abstract. Agrivoltaics systems generate spatially heterogeneous and temporally dynamic shading patterns, which can influence canopy development and complicate optical crop monitoring. This study evaluated a low-cost, fixed-imaging approach to monitor shade-induced variability in a lavender field under simulated agrivoltaics conditions. A consumer RGB camera was modified by removing the internal NIR-cut filter and adding a 660/850 nm dual-bandpass filter, so that the red and near-infrared proxy responses were captured primarily in the red and blue channels, respectively. Time-lapse images were acquired from a fixed viewpoint throughout the growing season and converted to a relative NDVI (NDVI*) calculated from the red and NIR digital number proxies. Since the optics, acquisition geometry, and processing workflow were kept constant, NDVI* was treated as an internally consistent indicator for spatial and temporal comparisons within the same system, and not as a calibrated reflectance measure. Two polygonal regions of interest, corresponding to the rows of lavender on either side of a 1-meter-wide vertical strip, were defined and reused for all dates. The analyses included NDVI* on both sides, the ΔNDVI* difference (right − left), the average hourly profile, and spatial profiles along a normalized uphill-downhill gradient. NDVI* increased from approximately 0.05 to over 0.20 over the course of the campaign, while the more shaded side showed consistently lower values. Overall, the results indicate that a fixed low-cost NIR-modified RGB camera can detect shade-induced asymmetries when used as a relative monitoring system.

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