Year-to-year blooming phenology observation using time-lapse digital camera images

Nagai, Shin; Yoshitake, Shinpei; Inoue, Tomoharu; Suzuki, Rikie; Muraoka, Hiroyuki; Nasahara, Kenlo Nishida; Saitoh, Taku M.

doi:10.2480/agrmet.d-13-00021

Cited by 10 publications

(4 citation statements)

References 25 publications

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“…The cameras adopted in phenological monitoring can feature a NIR channel (Nakaji et al 2011), but consumer-grade RGB cameras are more often used (Nagai et al 2016). The RGB data are converted to greenness indices to quantify the seasonal vegetation changes; the most widely used indices are the green excess index (GEI = 2G -R -B; Richardson et al 2007;Saitoh et al 2015;Nagai et al 2014) and the green chromatic coordinate index (Gcc = G/(R + G + B); Sonnentag et al 2012).…”

Section: Photography For Phenological Monitoringmentioning

confidence: 99%

An overview of in situ digital canopy photography in forestry

Chianucci

2019

Can. J. For. Res.

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Since the 1960s, canopy photography has been widely used in forestry. Hemispherical photography has been the most widely used technique, but a great drawback of this method is its perceived sensitivity to hemispherical image acquisition and processing. Over the last decade, several alternative photographic approaches using restricted view angle have been proposed. Cover photography acquired via a normal lens was the first of the recently introduced photographic techniques. Use of a restricted view (often fixed) lens has subsequently contributed to the extension of canopy photography to new sensors and platforms, which ultimately have provided answers to some previous challenges regarding within-crown clumping correction, isolated and urban tree measurements, understory assessment, operational leaf inclination angle measurements, and phenological monitoring. This study provides a comprehensive review of the use of canopy photography in forestry and describes the theory and definitions of the variables used to quantify canopy structure. A case study is presented to illustrate and compare the different features and performance of the existing overstory photographic techniques; the results make it possible to suggest sampling strategies for consistent overstory canopy photographic measurements. Emerging operational fields of canopy photography are also described and discussed.

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Section: Photography For Phenological Monitoringmentioning

confidence: 99%

An overview of in situ digital canopy photography in forestry

Chianucci

2019

Can. J. For. Res.

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“…However, the long distance between the camera and the target vegetation that is required to cover larger areas may prevent detailed phenological observations. Nagai et al ( 2014b ) found that the year-to-year variation in the timing of full blooming of Prunus sargentii could be detected at a canopy scale, but detailed continuous flowering phenology could not. Inoue et al ( 2014 ) reported that the threshold RGB-derived index values for detection of the timing of leaf flush and leaf fall could not be defined uniquely by analyzing phenological images taken with a fisheye lens.…”

Section: Phenological Observations By Digital Cameras and Spectral Ramentioning

confidence: 99%

Review: advances in in situ and satellite phenological observations in Japan

et al. 2015

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To accurately evaluate the responses of spatial and temporal variation of ecosystem functioning (evapotranspiration and photosynthesis) and services (regulating and cultural services) to the rapid changes caused by global warming, we depend on long-term, continuous, near-surface, and satellite remote sensing of phenology over wide areas. Here, we review such phenological studies in Japan and discuss our current knowledge, problems, and future developments. In contrast with North America and Europe, Japan has been able to evaluate plant phenology along vertical and horizontal gradients within a narrow area because of the country’s high topographic relief. Phenological observation networks that support scientific studies and outreach activities have used near-surface tools such as digital cameras and spectral radiometers. Differences in phenology among ecosystems and tree species have been detected by analyzing the seasonal variation of red, green, and blue digital numbers (RGB values) extracted from phenological images, as well as spectral reflectance and vegetation indices. The relationships between seasonal variations in RGB-derived indices or spectral characteristics and the ecological and CO2 flux measurement data have been well validated. In contrast, insufficient satellite remote-sensing observations have been conducted because of the coarse spatial resolution of previous datasets, which could not detect the heterogeneous plant phenology that results from Japan’s complex topography and vegetation. To improve Japanese phenological observations, multidisciplinary analysis and evaluation will be needed to link traditional phenological observations with “index trees,” near-surface and satellite remote-sensing observations, “citizen science” (observations by citizens), and results published on the Internet.

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“…Consequently, the real-time fluxes processed by OE can be known at a remote site through a cell-phone network without sending the 10-Hz data (typically 50 MB per day). When using OE-computed fluxes to control devices such as irrigation taps, field monitors (Nagai et al, 2014), and heat exchange facilities (Iwasaki et al, 2013), users should consider two additional factors. First, the QC procedure of OE has not yet been perfected.…”

Section: Compatibility With Other Instrumentsmentioning

confidence: 99%

Development of an onsite computation scheme of eddy-covariance fluxes

Ono

Maruyama

2015

J. Agric. Meteorol.

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Increasingly, agriculture and related industries rely on real-time measurements of surface fluxes and device control based on flux measurements. We have developed a program that computes the eddy-covariance fluxes of CO 2 and H 2 O in real-time on a commercial data logger model. The calculated flux values are targeted for device control. The performance of the program was compared with those of published software programs on maize field data. The calculated fluxes were consistent among the programs. Because practical onsite and real-time quality control procedures of flux measurements were unavailable, we developed a quality control procedure for our program that utilizes sensor disability signals. Filtering the sensor-disabled signals greatly improved the detection of anomalous fluxes during rainy periods. However, filtering the instationary fluxes by the standard deviation criterion was of limited practical use. By slightly modifying the source code, we can adapt the framework of our program to other combinations of sonic anemometer and gas analyzer.

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Year-to-year blooming phenology observation using time-lapse digital camera images

Cited by 10 publications

References 25 publications

An overview of in situ digital canopy photography in forestry

An overview of in situ digital canopy photography in forestry

Review: advances in in situ and satellite phenological observations in Japan

Development of an onsite computation scheme of eddy-covariance fluxes

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