Estimation of the Spectral Sensitivity Functions of Un-Modified and Modified Commercial Off-the-Shelf Digital Cameras to Enable Their Use as a Multispectral Imaging System for Uavs

Berra, Elias Fernando; Gibson-poole, Simon; MacArthur, Alasdair; Gaulton, Rachel; Hamilton, Amy

doi:10.5194/isprsarchives-xl-1-w4-207-2015

Cited by 30 publications

(31 citation statements)

References 12 publications

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“…We did not examine the response of our cameras employed. Berra et al [39] investigated the spectral sensitivity of several unmodified and one filter-modified camera, and found that all of the unmodified cameras showed similar ranges within the visible spectrum, with almost all of the RGB channels covering the range of 400-700 nm, but with varying degrees of sensitivity and substantial band overlap [39]. The filter-modified camera exhibited well-characterized sensitivities in the visible range that were narrower and of more equal intensities than those of the unmodified cameras.…”

Section: Camera Sensitivitymentioning

confidence: 99%

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Towards Remote Estimation of Radiation Use Efficiency in Maize Using UAV-Based Low-Cost Camera Imagery

Tewes

Schellberg

2018

Agronomy

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Radiation Use Efficiency (RUE) defines the productivity with which absorbed photosynthetically active radiation (APAR) is converted to plant biomass. Readily used in crop growth models to predict dry matter accumulation, RUE is commonly determined by elaborate static sensor measurements in the field. Different definitions are used, based on total absorbed PAR (RUE total ) or PAR absorbed by the photosynthetically active leaf tissue only (RUE green ). Previous studies have shown that the fraction of PAR absorbed (fAPAR), which supports the assessment of RUE, can be reliably estimated via remote sensing (RS), but unfortunately at spatial resolutions too coarse for experimental agriculture. UAV-based RS offers the possibility to cover plant reflectance at very high spatial and temporal resolution, possibly covering several experimental plots in little time. We investigated if (a) UAV-based low-cost camera imagery allowed estimating RUEs in different experimental plots where maize was cultivated in the growing season of 2016, (b) those values were different from the ones previously reported in literature and (c) there was a difference between RUE total and RUE green . We determined fractional cover and canopy reflectance based on the RS imagery. Our study found that RUE total ranges between 4.05 and 4.59, and RUE green between 4.11 and 4.65. These values are higher than those published in other research articles, but not outside the range of plausibility. The difference between RUE total and RUE green was minimal, possibly due to prolonged canopy greenness induced by the stay-green trait of the cultivar grown. The procedure presented here makes time-consuming APAR measurements for determining RUE especially in large experiments superfluous.

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Section: Camera Sensitivitymentioning

confidence: 99%

“…The spectral sensitivity of the bands and wavelength transmittance of filters of most COTS cameras are unknown, unless exposed to monochromatic light [39]. We did not examine the response of our cameras employed.…”

Section: Camera Sensitivitymentioning

confidence: 99%

Towards Remote Estimation of Radiation Use Efficiency in Maize Using UAV-Based Low-Cost Camera Imagery

Tewes

Schellberg

2018

Agronomy

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“…On image based analysis, Bayer filters in camera sensors have color overlaps, which would need to be removed to make measurements of specific light bands [19]. This means that in common cameras, RGB (Red, Green and Blue) channels represent broad and nonspecific sections of the light spectrum [20].…”

Section: Resultsmentioning

confidence: 99%

“…Light transmission values are presented in a standardized 0 to 1 scale. To overcome the limitations of a higher number of plant height values (20), as compared to a lower number of light transmission readings (17), the latest were taken randomly, without knowing the current height of the plants whose leaves were been assessed. …”

Section: Smartphone Based Measurements Of Light Transmission Through mentioning

confidence: 99%

Fast estimation of chlorophyll content on plant leaves using the light sensor of a smartphone

Pineda-Tobón¹,

Pérez²,

Gaviria-Palacio³

et al. 2017

DYNA

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Plant chlorophyll measurements can support nitrogen fertilization decisions. Using a 3D printed device and a red LED, here we tested the feasibility of using a smartphone ambient light sensor (ALS) to estimate leaf chlorophyll by light transmission. Its performance was evaluated by comparing 30 leaf sorghum (Sorghum bicolor (L.) Moench) transmission readings of the red LED (663 nm) obtained from the smartphone and a standard spectrometer, which showed a good coefficient of determination (r 2 = 0.9067). Additionally, a comparison between the ALS and a SPAD 502 TM (a commercial device for chlorophyll content estimation) was made with chrysanthemum (Dendranthema grandiflora Tzvelev) leaves, obtaining a good correlation between both measurements. Light transmission was also measured in S. bicolor flag leaves from plants growing in the greenhouse under increasing nitrogen fertilization. A clear fit between leaf light transmission and plant height was also observed, suggesting a simple, smartphone based estimation of plant's chlorophyll.Keywords: Plant nutrition; non-destructive chlorophyll meter; leaf light transmittance.Estimación rápida del contenido de clorofila en hojas usando el sensor de luz de un teléfono celular ResumenMedir clorofila puede apoyar decisiones de fertilización nitrogenada de plantas. Usando un dispositivo impreso en 3D y un LED rojo, aquí probamos la factibilidad de usar un teléfono celular para estimar clorofila por transmisión de luz. Al comparar 30 lecturas de trasmisión de luz roja (663 nm) por hojas de sorgo Sorghum bicolor (L.) Moench, obtenidas del teléfono y de un espectrómetro estándar, se encontró un buen coeficiente de determinación (r 2 = 0.9067). Adicionalmente, se hizo una comparación entre las lecturas del teléfono y un SPAD 502 TM (un dispositivo comercial para la estimación del contenido de clorofila) en hojas de crisantemo Dendranthema grandiflora Tzvelev, obteniendo una buena correlación entre ambas medidas. La transmisión medida en hojas de S. bicolor de plantas de invernadero fertilizadas con nitrógeno también presentó buen ajuste con la altura de las plantas, sugiriendo la posibilidad de estimar fácilmente el contenido de clorofila en hojas usando teléfonos inteligentes.Palabras clave: Nutrición vegetal; medición no destructiva de clorofila; transmisión de luz por hojas.

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“…However, the spectral response of consumer digital cameras is not provided by camera manufacturers. There are several methods for measuring and estimating the spectral response of a camera system including two standards for characterisation, one produced by the European Machine Vision Associations (EMVA (Berra et al, 2015;Bongiorno et al, 2013;MacDonald, 2015;Prasad and Brown, 2013). While there are several methods for measuring and estimating spectral response, a filter-based method used by MacDonald (2015) presented an accessible option that could include measurements into the NIR for a modified camera.…”

Section: Spectral Responsementioning

confidence: 99%

Spectral and 3d Cultural Heritage Documentation Using a Modified Camera

Webb

Robson

MacDonald

et al. 2018

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Spectral and 3D imaging techniques are used for museum imaging and cultural heritage documentation providing complementary information to aid in documenting the condition, informing the care, and increasing our understanding of objects. Specialised devices for spectral and 3D imaging may not be accessible for many heritage institutions, due to cost and complexity, and the modification of a consumer digital camera presents the potential of an accessible scientific tool for 2D and 3D spectral imaging. Consumer digital cameras are optimised for visible light, colour photography, but the underlying sensor is inherently sensitive to near ultraviolet, visible, and near infrared radiation. This research presents the characterisation of a modified camera to investigate the impact of the modification on the spectroradiometric and geometric image quality with the intention of the device being used as a scientific tool for cultural heritage documentation. The characterisation includes the assessment of 2D image quality looking at visual noise, sharpness, and sampling efficiency using the target and software associated with the Federal Agencies Digitization Guidelines Initiative. Results suggest that these modifications give rise to discrepancies in computed surface geometries of the order of ± 0.1 mm for small to medium sized objects used in the study and recorded in the round (maximum dimension 20 cm). Measuring the spectral response quantifies the modified camera as a scientific device for more accurate measurements and provides indications of wavelengths that could improve documentation based on sensitivity. The modification of a consumer digital camera provides a less expensive, high-resolution option for 2D and 3D spectral imaging.

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Estimation of the Spectral Sensitivity Functions of Un-Modified and Modified Commercial Off-the-Shelf Digital Cameras to Enable Their Use as a Multispectral Imaging System for Uavs

Cited by 30 publications

References 12 publications

Towards Remote Estimation of Radiation Use Efficiency in Maize Using UAV-Based Low-Cost Camera Imagery

Towards Remote Estimation of Radiation Use Efficiency in Maize Using UAV-Based Low-Cost Camera Imagery

Fast estimation of chlorophyll content on plant leaves using the light sensor of a smartphone

Spectral and 3d Cultural Heritage Documentation Using a Modified Camera

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