Comparing a Single-Sensor Camera With a Multisensor Camera for Monitoring Coffee Crop Using Unmanned Aerial Vehicles

Abstract

There exist two options for digital cameras that can capture the near-infrared (NIR) band. Conventional red-green-blue (RGB, visible bands) cameras with a single sensor provide NIR band visibility based on the removal of the internal NIR-blocking filter. Alternatively, multisensor cameras exist that have a specific sensor for each band. The modified RGB cameras are of a lower price. In this context, the objective of this study was to compare the performance of a modified RGB camera with that of a multisensor camera for obtaining the normalized difference vegetation index (NDVI) in an area with coffee cultivations. A multispectral camera with five sensors and another camera with only one sensor were used. The NDVI of the coffee field was also measured using the GreenSeeker handheld NDVI sensor manufactured by Trimble. The images were calibrated radiometrically based on the targets in shades of gray made of napa, and the NDVI was calculated after image calibration. The calibration curves showed a high coefficient of determination. The NDVI value obtained with the calibrated images from the cameras showed a significant correlation with the values obtained by the GreenSeeker NDVI sensor, making it possible to obtain the variability pattern of the vegetation index. However, the NDVI obtained using the multisensor camera was closer to the NDVI obtained by the GreenSeeker NDVI sensor.

Multisensor Speech Enhancement Technology in Music Synthesizer Design

“…He used a multispectral camera with five sensors and another camera with only one sensor. It turns out that the NDVI obtained with the multisensor camera is closer to the NDVI obtained with the GreenSeeker NDVI sensor [12].…”

Avaliação do índice de área foliar e índice de área da planta em floresta seca utilizando modelos simplificados em imagens de alta resolução com o uso de VANT

“…Percebem-se de forma bem definida a presença da estrada em todas as imagens, sendo um excelente algo para identificação dos valores de NDVI representativo da classe de solo exposto. Gomes et al (2021) avaliaram o NDVI resultante de câmera Micasense e Mapir, e observaram que a maioria dos pontos avaliados apresentaram valores de NDVI mais elevados quando determinado por meio da câmera Micasense. Segundo esses autores, isso se deve a vários fatores, dentre os quais, as próprias características da câmera, que utiliza uma mesma lente para capturar todas as imagens.…”

On the accuracy of infrared-converted drone cameras for use in vegetation and environmental monitoring

“…but it is necessary to verify the accuracy of spectral measurements made by these sensors. Despite being successfully used in studies (Lebourgeois et al 2008; Argolo dos Santos et al 2020), some authors reported lower measurement accuracy for infrared converted cameras, if compared to multi-sensor cameras or spectroscopes (Bueren et al 2015;Gomes et al 2021;Nijland et al 2014). This might partially be because the bands captured by single-sensor RGB camera is usually sensitive to light outside of the target wavelengths, and so measurements in speci c band may be polluted by light in other parts of the spectrum (Burggraaff et al 2019;Berra et al 2015).…”

“…Before such cameras can be recommended for operational use on farms, it is important to verify that spectral measurements and vegetation indices derived from the infrared converted camera correspond well to measurements made by other 'proper' multispectral cameras, or hand-held spectrometers. The study by Gomes et al (2021) investigated this dynamic for the Mapir Survey3W commercial infrared converted camera, by comparing it to the multispectral MicaSense RedEdge-MX camera. The study calculated the vegetation index NDVI of a coffee plantation using both cameras, as well as a handheld NDVI sensor.…”

“…The current study reinvestigates the question of the suitability of current commercial infrared converted cameras for use in vegetation condition monitoring. To improve continuity between research, we present a case-study that considers the same multispectral camera, handheld NDVI sensor and infrared converted camera used by the study of (Gomes et al 2021). Our experiment differs however in the calibration technique used, speci c spectral lter used in the infrared converted camera, and also the crop type that was captured.…”