Comparing canopy metrics derived from terrestrial and airborne laser scanning in a Douglas-fir dominated forest stand

Hilker, Thomas; Leeuwen, Martin van; Coops, Nicholas C.; Wulder, Michael A.; Newnham, Glenn; Jupp, David L.B.; Culvenor, Darius

doi:10.1007/s00468-010-0452-7

Cited by 166 publications

(156 citation statements)

References 40 publications

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“…TLS and ALS have been combined to estimate canopy structure at the plot level (Hilker et al 2010;Lovell et al 2003). In the present study, TLS and ALS are combined at tree level.…”

Section: Introductionmentioning

confidence: 99%

Estimation of stem attributes using a combination of terrestrial and airborne laser scanning

et al. 2012

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Properties of individual trees can be estimated from airborne laser scanning (ALS) data provided that the scanning is dense enough and the positions of field-measured trees are available as training data. However, such detailed manual field measurements are laborious. This paper presents new methods to use terrestrial laser scanning (TLS) for automatic measurements of tree stems and to further link these ground measurements to ALS data analyzed at the single tree level. The methods have been validated in six 80 × 80 m field plots in spruce-dominated forest (lat. 58° N, long. 13° E). In a first step, individual tree stems were automatically detected from TLS data. The root mean square error (RMSE) for DBH was 38.0 mm (13.1%) and the bias was 1.6 mm (0.5%). In a second step, trees detected from the TLS data were automatically co-registered and linked with the corresponding trees detected from the ALS data. In a third step, tree level regression models were created for stem attributes derived from the TLS data using independent variables derived from trees detected from the ALS data. Leave-oneout cross-validation for one field plot at a time provided an RMSE for tree level ALS estimates trained with TLS data of 46.0 mm (15.4%) for DBH, 9.4 dm (3.7%) for tree height, and 197.4 dm 3 (34.0%) for stem volume, which was nearly as accurate as when data from manual field inventory were used for training.

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“…TLS and ALS have been combined to estimate canopy structure at the plot level (Hilker et al 2010;Lovell et al 2003). In the present study, TLS and ALS are combined at tree level.…”

Section: Introductionmentioning

confidence: 99%

Estimation of stem attributes using a combination of terrestrial and airborne laser scanning

et al. 2012

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“…The similarity of the results from egg shaped tree crown models also implies that the validation is not sensitive to the exact choice of crown models. To obtain detailed ground measurements of the tree crowns, terrestrial laser scanning is a promising technique which is currently being developed for this purpose (Hilker et al 2010;Hosoi et al 2010;Lovell et al 2003). Most of the field inventory was done less than one growth season after the laser scanning except for the measurement of live crown height which was done two growth seasons after the laser scanning.…”

Section: Discussionmentioning

confidence: 99%

“…Harding et al (2001) estimated canopy height profiles for four selected forest stands from ALS data from SLICER using measurements from a telephoto lens calibrated to measure distances as ground truth. Hilker et al (2010) estimated canopy volume profiles for four forest stands from ALS point data and compared them with canopy volume profiles estimated from terrestrial laser scanning. Hosoi et al (2010) estimated Leaf Area Density (LAD) in a forest plot from ALS data and compared with LAD estimated from TLS data.…”

Section: Introductionmentioning

confidence: 99%

Estimation of 3D vegetation structure from waveform and discrete return airborne laser scanning data

Lindberg

Olofsson

Holmgren

et al. 2012

Remote Sensing of Environment

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Access to the published version may require journal subscription. Published with permission from: Elsevier.Standard set statement from the publisher: NOTICE: this is the author's version of a work that was accepted for publication in Remote Sensing of Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in REMOTE SENSING OF ENVIRONMENT, 118, MARCH, (2012) AbstractThis study presents and compares new methods to describe the 3D canopy structure with Airborne Laser Scanning (ALS) waveform data as well as ALS point data. The ALS waveform data were analyzed in three different ways; by summing the intensity of the waveforms in height intervals (a); by first normalizing the waveforms with an algorithm based on Beer-Lambert law to compensate for the shielding effect of higher vegetation layers on reflection from lower layers and then summing the intensity (b); and by deriving points from the waveforms (c). As a comparison, conventional, discrete return ALS point data from the laser scanning system were also analyzed (d). The study area was located in hemi-boreal, spruce dominated forest in the southwest of Sweden (Lat. 58° N, Long. 13° E). The vegetation volume profile was defined as the volume of all tree crowns and shrubs in 1 dm height intervals in a field plot and the total vegetation volume as the sum of the vegetation volume profile in the field plot. The total vegetation volume was estimated for 68 field plots with 12 m radius from the proportion between the amount of ALS reflections from the vegetation and the total amount of ALS reflections based on Beer-Lambert law. ALS profiles were derived from the distribution of the ALS data above the ground in 1 dm height intervals. The ALS profiles were rescaled using the estimated total vegetation volume to derive the amount of vegetation at different heights above the ground. The root mean square error (RMSE) for cross validated regression estimates of the total vegetation volume was 31.9% for ALS waveform data (a), 27.6% for normalized waveform data (b), 29.1% for point data derived from the ALS waveforms (c), and 36.5% for ALS point data from the laser scanning system (d). The correspondence between the estimated vegetation volume profiles was also best for the normalized waveform data and the point data derived from the ALS waveforms and worst for ALS point data from the laser scanning system as demonstrated by the Reynolds error index. The results suggest that ALS waveform data describe the volumetric aspects of vertical vegetation structure somewhat more accurately than ALS point data from the laser scanning system and that compensation for the shielding effect of higher vegetation layers is useful. The new methods for estimation of vegetation volume profiles from ALS data could be used i...

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“…In this study TLS-based measurements were found more reliable than conventional field methods. Therefore, TLS data should be considered a suitable tool to validate crown radius measurement from airborne laser scanning (Hilker et al 2010, Hauglin et al 2014 and it may also be useful for comparisons with high spatial resolution abovecanopy imagery. On the long term, airborne approaches for crown radius measurements are likely to be more widely applied to forest areas and they will benefit from detailed ground truth data by means of TLS.…”

Section: Tree Growth and Crown Dimensions In Fagus Sylvaticamentioning

confidence: 99%

Relationship between tree growth and physical dimensions of Fagus sylvatica crowns assessed from terrestrial laser scanning

Seidel¹,

Schall²,

Gille³

et al. 2015

iForest

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, Christian Ammer (2) Measurements of physical tree crown dimensions were of subjective character in the past, even though they can be considered important for the management of many silvicultural operations, such as timing of thinning operations. In our study we investigated if and how measures of physical crown dimensions of trees differed when quantified conventionally versus based on 3D-terrestrial laser scanning and how they are related to basal area increment. Some 24 randomly selected predominant or dominant beech trees between 90 and 110 yrs of age and of varying height were used as study trees. We hypothesized that tree crown dimensions obtained from scans are more closely related to tree radial growth than those obtained from conventional field measurements. It was found that from a variety of compared crown size characteristics the scan-based tree attributes mean crown radius, maximum area of the crown and crown projection area were most closely related to individual tree growth. We conclude that the horizontal extension of a tree crown in general is to be considered one of the most important drivers of tree growth. We also conclude that terrestrial laser scanning is a powerful tool to reliably measure physical crown dimensions and TLS-based measurements are more reliable than conventional ones.

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Comparing canopy metrics derived from terrestrial and airborne laser scanning in a Douglas-fir dominated forest stand

Cited by 166 publications

References 40 publications

Estimation of stem attributes using a combination of terrestrial and airborne laser scanning

Estimation of stem attributes using a combination of terrestrial and airborne laser scanning

Estimation of 3D vegetation structure from waveform and discrete return airborne laser scanning data

Relationship between tree growth and physical dimensions of Fagus sylvatica crowns assessed from terrestrial laser scanning

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