scholarly journals Application of LiDAR Data for the Modeling of Solar Radiation in Forest Artificial Gaps—A Case Study

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 821
Author(s):  
Leszek Bolibok ◽  
Michał Brach
Keyword(s):  
Solar Radiation ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Management Decision ◽  
Surface Model ◽  
Lidar Data ◽  
Size And Shape ◽  
Hemispherical Photographs ◽  
Actual Shape ◽  
The Impact

Artificial canopy gaps (forest openings) are frequently used as an element of regeneration cutting. The development of regeneration in gaps can be controlled by selecting a relevant size and shape for the gap, which will regulate the radiation microclimate inside it. Based on the size and shape of a gap computer models can assess where solar radiation is decreased or eliminated by the surrounding canopy. The accuracy of such models to a large extent depends on how the modeled shape of a gap matches the actual shape of the gap. The aim of this study was to compare the results of modeling solar radiation availability by applying Solar Radiation Tools (SRT) that use a different digital surface model (DSM) for a description of the shape of a studied gap, with the results of the analysis of 27 hemispherical photographs. The three-dimensional gap shape was approximated with the use of simple geometrical prisms or airborne laser scanning (LiDAR) data. The impact of two variations of exposure (automatic and manual underexposure) and two variations of automatic thresholding on the congruence of SRT and Gap Light Analyzer (GLA) results were studied. Taking into account information on differences in height between trees surrounding the gap enhanced the results of modeling. The best results were obtained when the boundary of the gap base estimated from LiDAR was expanded in all directions by a value close to a mean radius of the crowns of surrounding trees. Modeling of radiation conditions on the gap floor based on LiDAR data by an SRT program is efficient and more time effective than taking hemispherical photographs. The proposed solution can be successfully applied as a trustworthy source of information about light conditions in gaps, which is needed for management decision-making in silviculture.

scholarly journals Processing Strategy and Comparative Performance of Different Mobile LiDAR System Grades for Bridge Monitoring: A Case Study

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7550
Author(s):  
Yi-Chun Lin ◽  
Jidong Liu ◽  
Yi-Ting Cheng ◽  
Seyyed Meghdad Hasheminasab ◽  
Timothy Wells ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Lidar Data ◽  
Large Area ◽  
Comparative Performance ◽  
High Resolution Data ◽  
Bridge Monitoring ◽  
System Calibration ◽  
Wide Range ◽  
The Impact

Collecting precise as-built data is essential for tracking construction progress. Three-dimensional models generated from such data capture the as-is conditions of the structures, providing valuable information for monitoring existing infrastructure over time. As-built data can be acquired using a wide range of remote sensing technologies, among which mobile LiDAR is gaining increasing attention due to its ability to collect high-resolution data over a relatively large area in a short time. The quality of mobile LiDAR data depends not only on the grade of onboard LiDAR scanners but also on the accuracy of direct georeferencing information and system calibration. Consequently, millimeter-level accuracy is difficult to achieve. In this study, the performance of mapping-grade and surveying-grade mobile LiDAR systems for bridge monitoring is evaluated against static laser scanners. Field surveys were conducted over a concrete bridge where grinding was required to achieve desired smoothness. A semi-automated, feature-based fine registration strategy is proposed to compensate for the impact of georeferencing and system calibration errors on mobile LiDAR data. Bridge deck thickness is evaluated using surface segments to minimize the impact of inherent noise in the point cloud. The results show that the two grades of mobile LiDAR delivered thickness estimates that are in agreement with those derived from static laser scanning in the 1 cm range. The mobile LiDAR data acquisition took roughly five minutes without having a significant impact on traffic, while the static laser scanning required more than three hours.

scholarly journals Integration of Lidar Data into a Coupled Mesoscale–Land Surface Model: A Theoretical Assessment of Sensitivity of Urban–Coastal Mesoscale Circulations to Urban Canopy Parameters

2012 ◽  
Vol 29 (3) ◽  
pp. 328-346 ◽  
Author(s):  
Michael Carter ◽  
J. Marshall Shepherd ◽  
Steve Burian ◽  
Indu Jeyachandran
Keyword(s):  
Urban Environment ◽  
Land Surface ◽  
Urban Canopy ◽  
Vertical Motion ◽  
Sea Breeze ◽  
Surface Model ◽  
Lidar Data ◽  
Mesoscale Circulations ◽  
The Impact ◽  
Urban Weather

Abstract Urban–coastal circulations affect urban weather, dispersion and transport of pollutants and contaminants, and climate. Proper characterization and prediction of thermodynamic and dynamic processes in such environments are warranted. A new generation of observation and modeling systems is enabling unprecedented characterization of the three-dimensionality of the urban environment, including morphological parameters. Urban areas of Houston, Texas, are classified according to lidar-measured building heights and assigned typical urban land surface parameters appropriate to each classification. The lidar data were degraded from 1 m to the model resolution (1 km) with the goal of evaluating the impact of degraded resolution urban canopy parameters (UCPs) and three-dimensionality on the coastal–urban mesoscale circulations in comparison to typical two-dimensional urban slab approaches. The study revealed complex interactions between the sea breeze and urban heat island and offers a novel diagnostic tool, the bulk Richardson shear number, for identifying shallow mesoscale circulation. Using the Advanced Research Weather Research and Forecasting model (ARW-WRF) coupled to an atmosphere–land surface–urban canopy model, the authors simulated a theoretical sea-breeze day and confirmed that while coastal morphology can itself lead to complex sea-breeze front structures, including preferred areas of vertical motion, the urban environment can have an impact on the evolution of the sea-breeze mesoscale boundary. The inclusion of lidar-derived UCPs, even at degraded resolution, in the model’s land surface representation can lead to significant differences in patterns of skin surface temperature, convergence, and vertical motion, which have implications for many aspects of urban weather.

scholarly journals Three-dimensional Modeling of Carbon Fiber Cloth Surface from Dense and Scattered Points Cloud

2015 ◽  
Vol 9 (1) ◽  
pp. 152-157
Author(s):  
Cheng Jie ◽  
Chen Li
Keyword(s):  
Carbon Fiber ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Quality Analysis ◽  
Surface Model ◽  
Scanning System ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Fabric Surface

Fabric surface analysis, as part of fabric analysis, is very important for the textile manufacturing process and is traditionally based on human-labor or image processing which is a conventional automatic method. However, image quality is influenced by ambient light, background light and optical properties of the surface. In this paper, we present a three dimensional modeling techniques for the reconstruction of carbon-fiber fabric surface. Firstly, a dense and scattered points cloud is collected using 3D laser scanning system after necessary data quality analysis. Secondly, the original points cloud is preprocessed according to classification. Finally, three-dimensional fabric surface model is reconstructed using screened Poisson reconstruction algorithm. The experimental results show that the reconstructed model is acceptable.

scholarly journals Quality Assessment of Milling Pavement Surface Using 3D Line Laser Technology

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Bing Hui ◽  
Mu Guo ◽  
Xiaofang Liu
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Poor Quality ◽  
Surface Model ◽  
Premature Failure ◽  
Quality Work ◽  
Milled Surface ◽  
Surface Assessment

To ensure that a regular milled surface texture provides good bonding without residual distress, a new specification of milling surface assessment has been established for quantitatively evaluating the milled surface quality. This research explores the possibility of using three-dimensional (3D) laser scanning technology to develop an algorithm to obtain a milled surface model that can measure evaluating indicators, milling depth and texture depth, and identify poorly milled areas. A case study was conducted by using a laser scanning vehicular system to collect 3D continuous pavement transverse profiles data in a 500 m long segment of Highway S107. The results show that the proposed method is very promising and can measure the milling depth and texture depth to effectively and quantitatively differentiate between good- (milling depth between 47 mm and 53 mm and texture depth exceeding 2 mm) and poor-quality work. Moreover, the poorly milled areas such as those with residual distress and unmilled areas that will lead to premature failure can also be identified using the proposed method. The proposed method can effectively support remilling work and ensure the quality of the overlay pavement.

scholarly journals Impact of Lidar Data Assimilation on Low-Level Wind Shear Simulation at Lanzhou Zhongchuan International Airport, China: A Case Study

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1342
Author(s):  
Lanqian Li ◽  
Ningjing Xie ◽  
Longyan Fu ◽  
Kaijun Zhang ◽  
Aimei Shao ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Wind Shear ◽  
Three Dimensional ◽  
Wrf Model ◽  
Lidar Data ◽  
Positive Role ◽  
Low Level ◽  
Wind Lidar ◽  
The Impact ◽  
Doppler Wind Lidar

Doppler wind lidar has played an important role in alerting low-level wind shear (LLW). However, these high-resolution observations are underused in the model-based analysis and forecasting of LLW. In this regard, we employed the Weather Research and Forecasting (WRF) model and its three-dimensional variational (3D-VAR) system to investigate the impact of lidar data assimilation (DA) on LLW simulations. Eight experiments (including six assimilation experiments) were designed for an LLW process as reported by pilots, in which different assimilation intervals, assimilation timespans, and model vertical resolutions were examined. Verified against observations from Doppler wind lidar and an automated weather observing system (AWOS), the introduction of lidar data is helpful for describing the LLW event, which can represent the temporal and spatial features of LLW, whereas experiments without lidar DA have no ability to capture LLW. While lidar DA has an obviously positive role in simulating LLW in the 10–20 min after the assimilation time, this advantage cannot be maintained over a longer time. Therefore, a smaller assimilation interval is favorable for improving the simulated effect of LLW. In addition, increasing the vertical resolution does not evidently improve the experimental results, either with or without assimilation.

scholarly journals Heating Impact of a Tropical Reservoir on Downstream Water Temperature: A Case Study of the Jinghong Dam on the Lancang River

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 951 ◽  
Author(s):  
Bo Jiang ◽  
Fushan Wang ◽  
Guangheng Ni
Keyword(s):  
Solar Radiation ◽  
Water Temperature ◽  
Residence Time ◽  
Cold Water ◽  
Three Dimensional ◽  
Tropical Reservoir ◽  
Ecological Processes ◽  
Outflow Rate ◽  
Different Temperatures ◽  
The Impact

Reservoirs change downstream thermal regimes by releasing water of different temperatures to that under natural conditions, which may then alter downstream biodiversity and ecological processes. The hydropower exploitation in the mainstream Lancang-Mekong River has triggered concern for its potential effects on downstream countries, especially the impact of the released cold water on local fishery production. However, it was observed recently that the annual water temperature downstream of the Jinghong Reservoir (near the Chinese border) has increased by 3.0 °C compared to its historical average (1997–2004). In this study, a three-dimensional (3D) model of the Jinghong Reservoir was established to simulate its hydro- and thermodynamics. Results show that: (1) the impoundment of the Jinghong Reservoir contributed about 1.3 °C to the increment of the water temperature; (2) the solar radiation played a much more important role in comparison with atmosphere-water heat exchange in changing water temperatures; and (3) the outflow rate also imposed a significant influence on the water temperature by regulating the residence time. After impoundment, the residence time increased from 3 days to 11 days, which means that the duration that the water body can absorb solar radiation has been prolonged. The results explain the heating mechanism of the Jinghong Reservoir brought to downstream water temperatures.

scholarly journals Construction of Three-Dimensional Road Surface and Application on Interaction between Vehicle and Road

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Lu Yongjie ◽  
Huai Wenqing ◽  
Zhang Junning
Keyword(s):  
Quantitative Description ◽  
Three Dimensional ◽  
Point Contact ◽  
Estimation Method ◽  
Road Surface ◽  
Surface Model ◽  
Dynamical Process ◽  
Contact Points ◽  
Box Counting Dimension ◽  
The Impact

The quantitative description is given to three-dimensional micro and macro self-similar characteristics of road surface from the perspective of fractal geometry using FBM stochastic midpoint displacement and diamond-square algorithm in conjunction with fractal characteristics and statistical characteristics of standard pavement determined by estimation method of box-counting dimension. The comparative analysis between reconstructed three-dimensional road surface spectrum and theoretical road surface spectrum and correlation coefficient demonstrate the high reconstruction accuracy of fractal reconstructed road spectrum. Furthermore, the bump zone is taken as an example to reconstruct a more arbitrary 3D road model through isomorphism of special road surface with stochastic road surface model. Measurement is taken to assume the tire footprint on road surface to be a rectangle, where the pressure distribution is expressed with mean stiffness, while the contact points in the contact area are replaced with a number of springs. Two-DOF vehicle is used as an example to analyze the difference between three-dimensional multipoint-and-plane contact and traditional point contact model. Three-dimensional road surface spectrum provides a more accurate description of the impact effect of tire on road surface, thereby laying a theoretical basis for studies on the dynamical process of interaction of vehicle-road surface and the road friendliness.

Three-Dimensional Morphology of the Palate in Patients with Bilateral Complete Cleft Lip and Palate at the Stage of Permanent Dentition

2009 ◽  
Vol 46 (4) ◽  
pp. 399-408 ◽  
Author(s):  
Zbyněk Šmahel ◽  
Jana Velemínská ◽  
Pavel Trefný ◽  
Živa Müllerová
Keyword(s):  
Laser Scanning ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Substantial Reduction ◽  
Three Dimensional ◽  
Permanent Dentition ◽  
Cross Sectional ◽  
Size And Shape ◽  
Control Study ◽  
Dental Casts

Objective: Three-dimensional analysis of palate size and shape in 30 patients with complete bilateral cleft lip and palate (BCLPc) at the stage of permanent dentition. Design: Cross-sectional study based on laser scanning. Subjects: Thirty dental casts of boys approximately 15 years old with BCLPc and 28 dental casts of healthy boys of the same age. Interventions: Arched-lip suture with periosteoplasty and push-back of the palate with pharyngeal-flap surgery. Main Outcome Measures: Data on palate height in the 210 defined locations and on palate widths and profile area in 10 transverse sections. Results: The palate in patients with BCLPc was conical and narrower than in control study subjects, much more anteriorly than posteriorly. From the canines posteriorly, the palate was of almost constant height of 10 mm in the midline, being higher than in control study subjects at this location and lower more posteriorly (by 24% to 29% between molars). The area of transverse sections was reduced as compared with control study subjects from the first premolars posteriorly and reached more than 40% between molars. The length of the palate up to the first molars was not changed. Conclusion: BCLPc subjects exhibited narrow, low, and flat palate. Palate size and shape differences indicate a substantial reduction of the space for the tongue.

scholarly journals Big LIDAR Data in Digital Earth: Ways Out of Dead End

2020 ◽  
pp. paper46-1-paper46-10
Author(s):  
Ilya Rylskiy
Keyword(s):  
Data Storage ◽  
Spatial Data ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Alternative Methods ◽  
Measuring Instruments ◽  
Lidar Data ◽  
Data Sets ◽  
Spatial Data Sets ◽  
Limited Precision

During past 25 years, laser scanning has evolved from an experimental method into a fully autonomous family of Earth remote sensing methods. Now this group of methods provides the most accurate and detailed spatial data sets, while the cost of data is constantly falling, the number of measuring instruments (laser scanners) is constantly growing. The volumes of data that will be obtained during the surveys in the coming decades will allow the creation of the first sub-global coverage of the planet. However, the flip side of high accuracy and detail is the need to store fantastically large volumes of three-dimensional data without loss of accuracy. At the same time, the ability to work with the specified data in both 2D and 3D mode should be improved. Standard storage methods (file method, geodatabases, archiving, etc) solve the problem only partially. At the same time, there are some other alternative methods that can remove current restrictions and lead to the emergence of more flexible and functional spatial data infrastructures. One of the most flexible and promising ways of laser data storage and processing are quadtree and octree-based approaches. Of course, these approaches are more complicated than typical file data structures, that are commonly used for LIDAR data storage, but they allow users to solve some typical negative features of point datasets (processing speed, non-topological spatial structure, limited precision, etc.).

scholarly journals UAV LIDAR DATA PROCESSING: INFLUENCE OF FLIGHT HEIGHT ON GEOMETRIC ACCURACY, RADIOMETRIC INFORMATION AND PARAMETER SETTING IN DTM PRODUCTION

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 21-26
Author(s):  
K. Bakuła ◽  
M. Pilarska ◽  
W. Ostrowski ◽  
A. Nowicki ◽  
Z. Kurczyński
Keyword(s):  
Laser Scanning ◽  
Interpolation Method ◽  
Laser Scanner ◽  
Point Clouds ◽  
Lidar Data ◽  
Radiometric Calibration ◽  
Statistical Parameters ◽  
Flight Height ◽  
Vertical Error ◽  
The Impact

Abstract. This article presents the results of studies related to the impact of flight altitude of UAV equipped with lidar data on geometric and radiometric information. Experiments were conducted in two test areas by performing UAV test flight missions at different UAV Laser Scanner (ULS) altitudes. The results were compared to other parameters describing the point clouds in order to answer the questions related to their genesis and evaluation of a product from such high-resolution datasets. The accuracy of the elevation models was assessed on the basis of control points measured with GNSS RTK and Terrestrial Laser Scanning (TLS). Accuracy was assessed by statistical parameters and differential digital elevation models. The second issue raised in this work is the study of the decrease in radiometric value with an increase in platform elevation. The results of this work clearly indicate the very low impact of platform altitude on DTM vertical error. In presented works the suggestion about DTM resolution and interpolation method are provided. Moreover, the influence of flight height on the reflectance and intensity is notable, however, its impact is related more with the details and resolution of the raster than radiometric values considering the possibility of radiometric calibration of the intensity.

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