Three-dimensional Terrestrial Laser Scanning Research Articles

Giant sequoia (Sequoiadendron giganteum) in the UK: carbon storage potential and growth rates.

Giant sequoias (Sequoiadendron giganteum) are some of the UK's largest trees, despite only being introduced in the mid-nineteenth century. There are an estimated half a million giant sequoias and closely related coastal redwoods (Sequoia sempervirens) in the UK. Given the recent interest in planting more trees, partly due to their carbon sequestration potential and also their undoubted public appeal, an understanding of their growth capability is important. However, little is known about their growth and carbon uptake under UK conditions. Here, we focus on S. giganteum and use three-dimensional terrestrial laser scanning to perform detailed structural measurements of 97 individuals at three sites covering a range of different conditions, to estimate aboveground biomass (AGB) and annual biomass accumulation rates. We show that UK-grown S. giganteum can sequester carbon at a rate of 85 kg yr-1, varying with climate, management and age. We develop new UK-specific allometric models for S. giganteum that fit the observed AGB with r 2 > 0.93 and bias < 2% and can be used to estimate S. giganteum biomass more generally. This study provides the first estimate of the growth and carbon sequestration of UK open-grown S. giganteum and provides a baseline for estimating their longer-term carbon sequestration capacity.

Reprint of: Tree-tree interactions and crown complementarity: the role of functional diversity and branch traits for canopy packing

Previous studies have shown that tree species richness increases forest productivity by allowing for greater spatial complementarity of tree crowns (crown complementarity), which in turn results in more densely packed canopies. However, the mechanisms driving crown complementarity in tree species mixtures remain unclear. Here, we take advantage of a high-resolution, three-dimensional terrestrial laser scanning approach in the context of a large-scale biodiversity-ecosystem functioning experiment in subtropical China (BEF-China) to quantify the extent to which functional dissimilarity and divergences in branch traits between neighbouring trees affect crown complementarity at the scale of tree species pairs (i.e., two adjacent trees). Overall, we found no support that functional dissimilarity (divergence in morphological flexibility, specific leaf area and wood density) promotes crown complementarity. However, we show that the effects of functional dissimilarity (the plasticity of the outer crown structure) on crown complementarity vary in their magnitude and importance depending on branch trait divergences. Firstly, crown complementarity tended to be highest for tree species pairs that strongly differed in their functional traits, but were similar in branch density. In contrast, heterospecific pairs with a low functional trait divergence benefitted the most from a large difference in branch density compared with pairs characterised by a large functional dissimilarity. Secondly, the positive effects of increasing divergence in branching intensity (the plasticity of the inner crown structure) on crown complementarity became most important at low levels of functional dissimilarity, i.e. when species pairs were similar in their branch packing and vice versa. This suggests that species mixing allows trees to occupy canopy space more efficiently mainly due to phenotypic changes associated with crown morphology and branch plasticity. Our findings highlight the importance of considering outer and inner crown structures (e.g. branching architecture) to deepen our understanding of tree-tree interactions in mixed-species communities.

Quantitative monitoring method for analyzing the erosion of a landslide dam discharge channel using three-dimensional terrestrial laser scanning

While excavated discharge channels are often used for the emergency treatment of landslide-dammed lakes, the erosion of the discharge channel of a landslide dam is complex and rarely monitored on site. This work presents a quantitative monitoring method based on three-dimensional terrestrial laser scanning technology (TLS) for analyzing the erosion of a landslide dam discharge channel and then applies this method to evaluate the emergency engineering treatment of the 2018 Baige landslide-dammed lake in 2019. The proposed method uses TLS technology to accurately track the dynamic evolution of the discharge channel and to quantify the lateral erosion. Moreover, qualitatively analysis for vertical erosion is conducted based on the difference between actual and hypothetic river elevation. The results indicate that erosion processes of landslide deposition fluctuate as the results of flow discharge variations. Damage to the covering layer consisting of large particles is considered to be the main cause of this phenomenon. According to the relationship between erosion intensity (EI) and flow velocity, an empirical formula is deduced for erosion analysis. The key parameter in this formula is determined by the variation rate of discharge, the flow velocity, the composition of riverbank and the flow field distribution.

Tree-tree interactions and crown complementarity: The role of functional diversity and branch traits for canopy packing

Previous studies have shown that tree species richness increases forest productivity by allowing for greater spatial complementarity of tree crowns (crown complementarity), which in turn results in more densely packed canopies. However, the mechanisms driving crown complementarity in tree species mixtures remain unclear. Here, we take advantage of a high-resolution, three-dimensional terrestrial laser scanning approach in the context of a large-scale biodiversity-ecosystem functioning experiment in subtropical China (BEF-China) to quantify the extent to which functional dissimilarity and divergences in branch traits between neighbouring trees affect crown complementarity at the scale of tree species pairs (i.e., two adjacent trees). Overall, we found no support that functional dissimilarity (divergence in morphological flexibility, specific leaf area and wood density) promotes crown complementarity. However, we show that the effects of functional dissimilarity (the plasticity of the outer crown structure) on crown complementarity vary in their magnitude and importance depending on branch trait divergences. Firstly, crown complementarity tended to be highest for tree species pairs that strongly differed in their functional traits, but were similar in branch density. In contrast, heterospecific pairs with a low functional trait divergence benefitted the most from a large difference in branch density compared with pairs characterised by a large functional dissimilarity. Secondly, the positive effects of increasing divergence in branching intensity (the plasticity of the inner crown structure) on crown complementarity became most important at low levels of functional dissimilarity, i.e. when species pairs were similar in their branch packing and vice versa. This suggests that species mixing allows trees to occupy canopy space more efficiently mainly due to phenotypic changes associated with crown morphology and branch plasticity. Our findings highlight the importance of considering outer and inner crown structures (e.g. branching architecture) to deepen our understanding of tree-tree interactions in mixed-species communities.

Vegetation and Fluvial Geomorphology Dynamics after an Urban Fire

The goal of this research was to characterize the impact of invasive riparian vegetation on burn severity patterns and fluvial topographic change in an urban Mediterranean riverine system (Med-sys) after fire in San Diego, California. We assessed standard post-fire metrics under urban conditions with non-native vegetation and utilized field observations to quantify vegetation and fluvial geomorphic processes. Field observations noted both high vegetation loss in the riparian area and rapidly resprouting invasive grass species such as Arundo donax (Giant Reed) after fire. Satellite-based metrics that represent vegetation biomass underestimated the initial green canopy loss, as did volumetric data derived from three-dimensional terrestrial laser scanning data. Field measurements were limited to a small sample size but demonstrated that the absolute maximum topographic changes were highest in stands of Arundo donax (0.18 to 0.67 m). This work is the first quantification of geomorphic alterations promoted by non-native vegetation after fire and highlights potential grass–fire feedbacks that can contribute to geomorphic disruption. Our results support the need for ground-truthing or higher resolution when using standard satellite-based indices to assess post-fire conditions in urban open spaces, especially when productive invasive vegetation are present, and they also emphasize restoring urban waterways to native vegetation conditions.

Performance Evaluation of a Bridge Infrastructure Using Terrestrial Laser Scanning Technology

Abstract Monitoring techniques, used to assess the condition of infrastructures, have been impacted by the rapid developments in remote sensing technology. While these technologies have improved performance evaluation, cogent procedures for evaluating ground movements have yet to be developed. This article presents an application of the three-dimensional terrestrial laser scanning (3D-TLS) technology for assessing the performance of bridge infrastructures, including highway embankments, bridge decks, approach slabs, abutments, and columns supported on drilled shafts. In this research study, a framework was developed, using 3D-TLS technology, to evaluate the ground movements. The survey process, variables, and analysis were demonstrated by performing the field operations at a rehabilitated bridge infrastructure located in North Texas. The analysis depicted vertical movements that were experienced by the approach slab during different time periods. The validation of 3D-TLS results was performed by comparing the vertical movements from the four horizontal inclinometers installed underneath the pavement. The comparison studies revealed similar movement patterns of both inclinometers and processed scans, while the latter provided detailed soil movements over a larger area.

DISCUSSION ON RESTORATION DESIGN OF LANDSCAPE SITE BASED ON 3DTERRESTRIAL LASER SCANNING : A CASE STUDY OF QIWANG HALL IN SUMMER PALACE, BEIJING, CHINA

Abstract. In recent years, new technologies have been developed and applied in the field of heritage conservation, such as Three-dimensional-terrestrial laser scanning (TLS). The academia pays more attention to the heritages which remain relatively intact, but neglects those destroyed. Research on information collection and restoration of sites helps to better protect the damaged sites and deepen people's understanding of the value of heritage. This study will conduct a detailed survey of the status quo of the site, providing basic information for the protection of the site. At the same time, the existing archives and documents are excavated and sorted out, and the restoration research of Qiwang Hall is carried out on the basis of the site and archives, which can make up for the shortcomings of the previous research and provide a reference of methods for the relevant research.

Laser Scanning-Based Updating of a Finite-Element Model for Structural Health Monitoring

Many of experimental measurements in the field of finite-element method (FEM) model updating focus on dynamic testing, while attention to static measurements is relatively insufficient. Due to the fact that the static measurements have a high precision and strong noise immunity, using static measurements in FEM updating has great significance and advantages. Three-dimensional terrestrial laser scanning (TLS) technology is one of the most promising methods used in static measurements. In this paper, based on TLS measurement, we updated the current FEM model by response surface methodology.

Mapping and characterization of rock discontinuities in a tunnel using 3D terrestrial laser scanning

This paper attempts to evaluate various methods of geometrical discontinuity characterization using point clouds that are generated with three-dimensional terrestrial laser scanning (3DTLS) in a tunnel. The use of 3DTLS to support discontinuity mapping in tunnels enables the acquisition of a large amount of data without limitations in terms of the tunnel position (wall or roof). Thus, the discontinuity orientation, trace length and frequency were statistically analyzed in different regions of the tunnel to determine the most representative data. Different methods of estimating the mean trace length were compared while considering the variations in the rock face orientation in the tunnel, and the unbiased standard deviation of the trace length was evaluated. The frequencies of discontinuity sets were obtained using scanlines, and aspects of window sampling for density (areal frequency) estimates in tunnels are discussed. The mean trace lengths obtained using rectangular sampling windows (considering the relative frequency of the traces) are more suitable for estimates of different rock face orientations, particularly when the orientation of the discontinuity set varies significantly. In this case, measurements of samples from the tunnel roof presented higher values for both frequency and mean trace length estimates, which demonstrates the importance of data acquisition and evaluation in this region.

Precision Weed Detection using Terrestrial Laser Scanning Techniques

Weeds compete with cultivated plants for nutrients and water in agricultural fields and orchards. Site-specific precision plant protection requires optimal plant-specific pesticide combinations and quantities. The first step in precision weed control is to map and detect weeds. Active and passive remote-sensing tools are available for weed detection. This article presents a study of precision weed detection using three-dimensional terrestrial laser scanning in an apple (Malus domestica) orchard. The laser scanner was able to identify two monocotyledonous (Digitaria sanguinalis, Echinochloa crus-galli) and two dicotyledonous (Galinsoga parviflora, Portulaca oleracea) weed species. In addition to weed identification, weed coverage was also determined using three algorithms. The results indicate that laser scanning has the potential for fast, accurate weed detection and could support the development of a plant-specific, selective, precision weed-control system that reduces water and pesticide use in orchards.

Linking laser scanning to snowpack modeling: Data processing and visualization

SnowSim is a newly developed physical snowpack model that can use three-dimensional terrestrial laser scanning data to generate model domains. This greatly simplifies the input and numerical simulation of snow covers in complex terrains. The program can model two-dimensional cross sections of general slopes, with complicated snow distributions. The model predicts temperature distributions and snow settlements in this cross section. Thus, the model can be used for a wide range of problems in snow science and engineering, including numerical investigations of avalanche formation. The governing partial differential equations are solved by means of the finite element method, using triangular elements. All essential data for defining the boundary conditions and evaluating the simulation results are gathered by automatic weather and snow measurement sites. This work focuses on the treatment of these measurements and the simulation results, and presents a pre- and post-processing graphical user interface (GUI) programmed in Matlab.

Three-Dimensional Laser Imaging as a Valuable Tool for Specifying Changes in Breast Shape After Augmentation Mammaplasty

Three-dimensional (3D) terrestrial laser scanning (TLS) is a valuable method for measuring shapes of objects and for obtaining quantitative measurements. These qualities of the 3D laser scanner have proved to be useful in reconstructive breast surgery. This study investigated various 3D parameters to obtain an optimal objective visualization of the breast after cosmetic augmentation mammaplasty. The objects are represented in a point cloud, which comprises millions of x, y, and z coordinates representing a virtual image. The quantification of 3D points shows changes in height (z coordinate) at any chosen point on the augmented breast (x and y coordinates). To give visual feedback on the change in dimensions, a color elevation scheme was applied on the reconstructed surface of the breast. As a quantifying description, a sagittal B-spline was chosen in a plane through the nipple to obtain the breast shape via the lateral profile. Pre- and postoperative clear images were obtained. The color elevation model showed an increased projection and upper pole fullness after augmentation. The B-spline showed the gain in projection in a sagittal plane through the nipple. Three-dimensional TLS is capable of objectifying changes in shape after augmentation mammaplasty. This imaging technique represents superior visualization of the breast shape and can serve as a valuable tool to determine the changing dimensions of the breasts after augmentation mammaplasty.