Estimating forest leaf area using cover and fullframe fisheye photography: Thinking inside the circle

Macfarlane, Craig; Grigg, A. H.; Evangelista, C. C.

doi:10.1016/j.agrformet.2007.05.001

Cited by 99 publications

(96 citation statements)

References 32 publications

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“…Recent studies confirmed the accuracy of digital hemispherical photography in estimating forest canopy properties (Englund et al 2000, Jonckheere et al 2005, Leblanc et al 2005, Macfarlane et al 2007a, Ryu et al 2010a. Moreover, new photographic techniques have been tested recently, confirming the high potentiality of digital photography (Macfarlane et al 2007b, Ryu et al 2010b, Chianucci & Cutini 2013). …”

Section: Foreground To Digital Hemispherical Photographymentioning

confidence: 58%

“…By contrast, remotely sensed vegetation indexes have novel potential but still need cross calibration by means of ground-based observations (Wang et al 2004). As a consequence, indirect measures of forest canopy properties using ground-based instruments have long been implemented, as documented by the rich literature (i.e., Chen et al 1997, Cutini et al 1998, Breda 2003, Macfarlane et al 2007b.…”

Section: Introductionmentioning

confidence: 99%

“…However, direct measurements of forest canopy are particularly challenging to obtain, owing to inherent difficulties in making direct measurements of forest, high levels of spatial and temporal variability, and difficulty of generalizing local measurements to the landscape scale (Chen & Cihlar 1995, Chen et al 1997, Macfarlane et al 2007b.…”

Section: Introductionmentioning

confidence: 99%

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Digital hemispherical photography for estimating forest canopy properties: current controversies and opportunities

Chianucci¹,

Cutini²

2012

iForest

103

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Hemispherical photography has been used since the 1960s in forest ecology. Nevertheless, specific constraints related to film cameras have progressively prevented widespread adoption of this photographic method. Advances in digital photographic technology hold great promise to overcome the major drawbacks of hemispherical photography, particularly regarding field techniques and image processing aspects. This contribution is aimed to: (i) provide a basic foreground of digital hemispherical photography; (ii) illustrate the major strengths and weakness of the method; (iii) provide an reliable protocol for image acquisition and analysis, to get the most out of using hemispherical photography for canopy properties extraction

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Section: Foreground To Digital Hemispherical Photographymentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

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Digital hemispherical photography for estimating forest canopy properties: current controversies and opportunities

Chianucci¹,

Cutini²

2012

iForest

103

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“…Therefore, to date, an ideally suitable application for thermal cameras is cover photography as introduced by Macfarlane et al (2007aMacfarlane et al ( , 2007b which is a single view-angle method using a narrow field-ofview lens. This method has advantages over hemispherical photography (Pekin & Macfarlane 2009), e.g., more accurate gap retrieval (Ryu et al 2010, Chianucci & Cutini 2013, and is much closer to the thermal photography approach.…”

Section: Discussionmentioning

confidence: 99%

“…Cover photography (Macfarlane et al 2007a(Macfarlane et al , 2007b and hemispherical photography in particular are terrestrial remotesensing techniques widely employed to produce upward facing images of sections of the forest canopy (Hale & Edwards 2002). The term "hemispherical" here refers to the approach of taking wide-angle photographs.…”

Section: Introductionmentioning

confidence: 99%

Thermal canopy photography in forestry - an alternative to optical cover photography

Nölke¹,

Beckschäfer²,

Kleinn³

2015

iForest

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Rapid assessment of forest canopy and light regime using smartphone hemispherical photography

et al. 2017

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Hemispherical photography (HP), implemented with cameras equipped with “fisheye” lenses, is a widely used method for describing forest canopies and light regimes. A promising technological advance is the availability of low‐cost fisheye lenses for smartphone cameras. However, smartphone camera sensors cannot record a full hemisphere. We investigate whether smartphone HP is a cheaper and faster but still adequate operational alternative to traditional cameras for describing forest canopies and light regimes.We collected hemispherical pictures with both smartphone and traditional cameras in 223 forest sample points, across different overstory species and canopy densities. The smartphone image acquisition followed a faster and simpler protocol than that for the traditional camera. We automatically thresholded all images. We processed the traditional camera images for Canopy Openness (CO) and Site Factor estimation. For smartphone images, we took two pictures with different orientations per point and used two processing protocols: (i) we estimated and averaged total canopy gap from the two single pictures, and (ii) merging the two pictures together, we formed images closer to full hemispheres and estimated from them CO and Site Factors. We compared the same parameters obtained from different cameras and estimated generalized linear mixed models (GLMMs) between them.Total canopy gap estimated from the first processing protocol for smartphone pictures was on average significantly higher than CO estimated from traditional camera images, although with a consistent bias. Canopy Openness and Site Factors estimated from merged smartphone pictures of the second processing protocol were on average significantly higher than those from traditional cameras images, although with relatively little absolute differences and scatter.Smartphone HP is an acceptable alternative to HP using traditional cameras, providing similar results with a faster and cheaper methodology. Smartphone outputs can be directly used as they are for ecological studies, or converted with specific models for a better comparison to traditional cameras.

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Estimating forest leaf area using cover and fullframe fisheye photography: Thinking inside the circle

Cited by 99 publications

References 32 publications

Digital hemispherical photography for estimating forest canopy properties: current controversies and opportunities

Digital hemispherical photography for estimating forest canopy properties: current controversies and opportunities

Thermal canopy photography in forestry - an alternative to optical cover photography

Rapid assessment of forest canopy and light regime using smartphone hemispherical photography

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