Effects of voxel size and sampling setup on the estimation of forest canopy gap fraction from terrestrial laser scanning data

Cifuentes, Renato; Zande, Dimitry Van der; Farifteh, Jamshid; Salas, Christian; Coppin, Pol

doi:10.1016/j.agrformet.2014.04.013

Cited by 60 publications

(26 citation statements)

References 36 publications

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“…The point cloud of a tree, which is not more than a list of three‐dimensional Cartesian coordinates, is simply converted into what is often named “voxel models” (voxel = (“volumetric pixels” ≈ boxes) of different resolutions, and the number of voxels needed to “cover” the tree's point cloud is counted. Voxel models were used in the past in various studies dealing with laser scanning data (e.g., Cifuentes, Van der Zande, Farifteh, Salas, & Coppin, ; Juchheim, Ammer, Schall, & Seidel, ; Juchheim, Annighöfer et al., ). An example for the calculation of the box dimension of an exemplary tree is presented in Figure .…”

Section: Methodsmentioning

confidence: 99%

A holistic approach to determine tree structural complexity based on laser scanning data and fractal analysis

Seidel

2017

Ecology and Evolution

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The three‐dimensional forest structure affects many ecosystem functions and services provided by forests. As forests are made of trees it seems reasonable to approach their structure by investigating individual tree structure. Based on three‐dimensional point clouds from laser scanning, a newly developed holistic approach is presented that enables to calculate the box dimension as a measure of structural complexity of individual trees using fractal analysis. It was found that the box dimension of trees was significantly different among the tested species, among trees belonging to the same species but exposed to different growing conditions (at gap vs. forest interior) or to different kinds of competition (intraspecific vs. interspecific). Furthermore, it was shown that the box dimension is positively related to the trees’ growth rate. The box dimension was identified as an easy to calculate measure that integrates the effect of several external drivers of tree structure, such as competition strength and type, while simultaneously providing information on structure‐related properties, like tree growth.

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Section: Methodsmentioning

confidence: 99%

A holistic approach to determine tree structural complexity based on laser scanning data and fractal analysis

Seidel

2017

Ecology and Evolution

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“…In that study, the 55-60 zenith range was the highest zenith range. Cifuentes et al [38] inspected the effects of voxel size (ranging from 1 cm to 5 cm) and sampling design on the estimation of the forest canopy gap fraction using TLS data. The root mean square error (RMSE) of gap fraction estimates for intermediate and mature forests using point clouds at different locations (1 m, 10 m, and 14 m from the centre) decreased as voxel size increased.…”

Section: Canopy Height Profiles Extractionmentioning

confidence: 99%

Combining Airborne and Terrestrial Laser Scanning Technologies to Measure Forest Understorey Volume

Liu

Pang

et al. 2017

Forests

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Abstract:A critical component of the forest ecosystem, the understorey supports the vast majority of wildlife habitat and total ecosystem floristic diversity. Remote sensing data have been developed to provide information at different scales for surveys of forest ecosystems, but obtaining information about the understorey remains a challenge. As rapid and efficient tools for forest structure attribute estimation, Airborne Laser Scanning (ALS) and Terrestrial Laser Scanning (TLS) have attracted much attention. We examine the relationship between ALS and TLS data and detect changes in the forest understorey caused by forest-tending events in the study area. We conducted trials in five plots within a young Khasi pine (Pinus kesiya Royle ex Gord.) plantation in Yunnan province, China, before and after forest tending. We collected bi-temporal ALS data in this area and TLS data from 10 scanning stations. Canopy height profiles were retrieved from ALS and TLS data, and understorey material volume retrieved from filled TLS voxels volume agreed well with the understorey point clouds percentile distribution (PD) obtained from ALS data. The PD value for the understorey from ALS multiplied by the percentage of ALS return points in the overstorey had a stronger correlation (R 2 = 0.90) with the TLS-derived understorey material volume than did the ALS PD value for the understorey only (R 2 = 0.71). Taking the effect of the overstorey into consideration will improve evaluations of forest understorey parameters from ALS data. This study confirmed the potential of TLS as a validation tool to assess the accuracy of forest understorey material volume estimation at large scales using ALS data.

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“…TLS data can thus replace the need to take hemispherical photographs in points of interest, such as above seedlings in gaps (Woodgate et al, 2015). Hemispherical photographs simulated from the scan data as presented by several earlier studies (Danson et al, 2007;Seidel et al, 2012;Cifuentes et al, 2014;Hancock et al, 2014) could easily be applied to canopy gaps. This would allow determining the light regime in the gap area in dependence of the 3D-shape of the gap, compass directions and geographical position.…”

Section: Discussion and Outlookmentioning

confidence: 96%

Describing forest canopy gaps efficiently, accurately, and objectively: New prospects through the use of terrestrial laser scanning

Seidel

Ammer

Puettmann

2015

Agricultural and Forest Meteorology

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Effects of voxel size and sampling setup on the estimation of forest canopy gap fraction from terrestrial laser scanning data

Cited by 60 publications

References 36 publications

A holistic approach to determine tree structural complexity based on laser scanning data and fractal analysis

A holistic approach to determine tree structural complexity based on laser scanning data and fractal analysis

Combining Airborne and Terrestrial Laser Scanning Technologies to Measure Forest Understorey Volume

Describing forest canopy gaps efficiently, accurately, and objectively: New prospects through the use of terrestrial laser scanning

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