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Solar Radiation in Forests: Theory for Hemispherical Photography
2017Solar radiation is not only the main source of energy for life on Earth, but it is also the natural source of light for the optical acquisition of information, such as for vision and photography . Natural sunlight provides the illumination required for taking hemispherical photographs in forests.
Patrick Schleppi, Alain Paquette
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Automatic thresholding for digital hemispherical photography
Canadian Journal of Forest Research, 2004This paper proposes an automatic thresholding method for the discrimination of sky and canopy elements in color hemispherical photographs taken with a digital camera (Nikon Coolpix 950). The exposures for photography were principally determined on the basis of zenith luminance. DIFphoto, which is diffuse transmittance calculated from the hemispherical
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Measurement of Forest Structure with Hemispherical Photography
2017This chapter presents the theoretical concepts necessary to link optical sensor data to forest structural attributes . Forest stand architecture is relatively complex and spatially variable, and many approaches can be used for its measurement: from traditional forest measurements in ground plots , to the statistical representation of forest attributes ...
Sylvain G. Leblanc, Richard A. Fournier
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The computation of foliage clumping index using hemispherical photography
Agricultural and Forest Meteorology, 2009Hemispherical photography (HP) is extensively used for both canopy architecture such as leaf area index (LAI), and solar radiation regime determinations under forest canopies. This is done mainly by assuming that foliage elements occur in a spatially random manner.
Alemu Gonsamo, Petri Pellikka
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DETERMINATION OF THE PLANT AREA INDEX OF OLIVE TREES BY HEMISPHERICAL PHOTOGRAPHY
Acta Horticulturae, 1999Destructive measurements of leaf area index (LAT) were compared with values of plant area index (PAI) obtained by hemispherical photography in an unevenly-aged olive orchard in Southern Tuscany, Italy. The measured LAI destructively increased from 0.8 in one-year old plants to 2.8 in 10-year-old trees.
GUCCI, RICCARDO +3 more
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Leaf area index estimates obtained for clumped canopies using hemispherical photography
Agricultural and Forest Meteorology, 1999A method has been developed to improve estimates of leaf area index determined from hemispherical images of plant canopies. The approach used has been to modify existing techniques for analysis of gap fraction at a range of zenith angles. Conventional analytical techniques determine the gap fraction for a number of concentric annuli and then calculate ...
P.R van Gardingen +4 more
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Canopy Architectural Models in Support of Methods Using Hemispherical Photography
2017One of the most important limitations regarding the in situ measurement of forest canopies is the relative lack of knowledge of canopy structure. Yet the three-dimensional (3D) arrangement of canopy components is difficult to measure because of the significant spatial and temporal heterogeneity of canopy structure over a wide range of scales.
Jean-François Côté +2 more
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Hemispherical Photography in Support of Forest Inventory and Silviculture
2017Hemispherical photography (HP) can be used in support of silviculture and forest inventory. At the tree level, HP can be used to estimate attributes such as tree architecture, crown dimensions, and volume of standing trees. At the stand level, there are relationships between indices extracted from HP and stand attributes such as density, basal area ...
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Primary results of using hemispherical photography for advanced GPS mission planning
The 9th International Conference "Environmental Engineering 2014", 2014This paper presents a preliminary results of using hemispherical digital photography obtained from fish-eye lens for advanced GPS mission planning. Nowadays, reach GPS constellation ensure availability of 3 dimensional position, anytime, anywhere over the world, except, where the obstructions prevent signal receiving occur.
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Assessment of automatic gap fraction estimation of forests from digital hemispherical photography
Agricultural and Forest Meteorology, 2005Thresholding is a central part of the analysis of hemispherical images in terms of gap fraction and leaf area index (LAI), and the selection of optimal thresholds has remained a challenge over decades. The need for an objective, automatic, operatorindependent thresholding method has long been of interest to scientists using hemispherical photography ...
Inge Jonckheere +3 more
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