Laser Scanning Measurements Research Articles

Deformation behavior analysis of composite structures under monotonic loads based on terrestrial laser scanning technology

A statical experiment of composite structures based on Terrestrial Laser Scanner (TLS) measurement was conducted to investigate the deformation behavior of arch structure. In this paper, laser scanning measurement data of thirteen epochs are collected and data are extracted and processed with MATLAB. How to improve the reliability of composite structural deformation monitoring is one of the key problems in the field of health monitoring. Comparing with the traditional monitoring methods, TLS monitoring has better flexibility and especially in the actual projects. Because some embedded sensors failed after running several years, other means of structural deformation monitoring are required. The goal of this paper is to investigate the feasibility of TLS technology, which is higher efficiency, accuracy and intelligence, to supplement or substitute the traditional monitoring methodologies.

Monotonic loads experiment for investigation of composite structure based on terrestrial laser scanner measurement

Reinforced concrete is nowadays a ubiquitous and indispensable building material and is applied diffusely in various types of engineering structures which are regularly required to satisfy the high demands of comfort and security. Therefore, an accurate estimation of the ultimate load is essential to monitor the deformation and assess the safety of reinforced concrete structures.The terrestrial laser scanner is considered one of the highest precision monitoring devices used to gauge the deformation of composite structures. Measurements by TLS are carried out for arch-reinforced concrete structures. With the latter, it is necessary to adapt a new displacement-strain relationship which is different from linear structures, due to the curvature and a continuously variable slope of an arch structure which introduce additional internal forces. The goal of this paper is to investigate the accessional deformation of arch structures which is caused by the curvature of the arch and a continuously variable slope.

DMI measurements impact on a position estimation with lack of GNSS signals during Mobile Mapping

Nowadays, Mobile Laser Scanning is common in use in addition to geodesy measurements. The data which are provided by the system characterizes with high precision and flexibility. To precise mapping, the accuracy of the data should be maintained. In Poland, according to the minister’s dispositions, the accuracy of the data should not exceeded 10 cm. With fully operated system it is easy to uphold, but there is a situation when a signal from an INS is not enough to preserve it. This paper is presenting the solution of a DMI use in Mobile Laser Scanning measurements as the support for position estimation during lack of satellites signal situation when the vehicle with the platform was entered the tunnel. To comparison the results a several of entrances was performed. This research helps understand the use of DMI in mobile data acquisition in different acquiring situations.

INFLUENCES OF RANGE AND INCIDENCE ANGLE ON MEASUREMENTS OF A FULL-WAVEFORM TERRESTRIAL LASER SCANNER VZ - 400

Full-waveform terrestrial laser scanning is a recent technology which is able to digitize and record the complete waveform of the backscattered echo. It gives additional information about the structure and physical backscattering properties of the illuminated surface (reflectance and geometry). Some authors focus on the data quality of a terrestrial laser scanner. Some of them are interested in the influence of the materials on the measurements of a full-waveform terrestrial laser scanner. Most of them are interested in the geometrical accuracy of the scanner (errors of instrumental axis, range accuracy using target, etc.). The aim of this article is to find out the influences of target geometry on the measurement of the full waveform terrestrial laser scanner VZ – 400. The emphasis was put on the influence of range to target and incidence angle.

BIM technology in geotechnical engineering in terms of impact high building "Mogilska Tower" in Cracow of existing building development

The article presents the use of BIM design method in geotechnical issues. BIM was used in the modeling of high building “Mogilska Tower” in Cracow. The object, as one of the few in Cracow, will have three underground storeys. High building with underground levels requires checking the impact of the implementation of a deep excavation on existing buildings. Analysis of settlement impact caused by deep excavation and the planned load of the building is based on the guidelines contained in the ITB (KOTLICKI, WYSOKIŃSKI 2002) standards by the simplified method and detailed method determined on the basis of numerical analysis. The article presents the results of the vertical deformation of ground adjacent to the existing object. The results of the calculations were compared with the limit values shown in ITB and PN-81/B-03020 (1985). Numerical analysis was performed in the spatial state of stress and strain model. It takes into account the spatial layout of the geotechnical subgrade and the terrain shape obtained by the measurement of terrestrial laser scanner. Subgrade was modeled elastic-plastic model of Mohr-Coulomb with linear condition of plasticity. Identified the influence and range of deep excavation and loads of the planned high building on existing development.

Towards System Calibration of Panoramic Laser Scanners from a Single Station.

Terrestrial laser scanner measurements suffer from systematic errors due to internal misalignments. The magnitude of the resulting errors in the point cloud in many cases exceeds the magnitude of random errors. Hence, the task of calibrating a laser scanner is important for applications with high accuracy demands. This paper primarily addresses the case of panoramic terrestrial laser scanners. Herein, it is proven that most of the calibration parameters can be estimated from a single scanner station without a need for any reference information. This hypothesis is confirmed through an empirical experiment, which was conducted in a large machine hall using a Leica Scan Station P20 panoramic laser scanner. The calibration approach is based on the widely used target-based self-calibration approach, with small modifications. A new angular parameterization is used in order to implicitly introduce measurements in two faces of the instrument and for the implementation of calibration parameters describing genuine mechanical misalignments. Additionally, a computationally preferable calibration algorithm based on the two-face measurements is introduced. In the end, the calibration results are discussed, highlighting all necessary prerequisites for the scanner calibration from a single scanner station.

New insights on permafrost genesis and conservation in talus slopes based on observations at Flüelapass, Eastern Switzerland

The talus slope at Flüelapass was the first mountain permafrost study site in Switzerland in the 1970s and the presence of ice-rich permafrost at the foot of the slope has been investigated in the context of several studies focusing on the role of snow cover distribution. We review previously developed hypotheses and present new ones using various data sources, such as temperature measurements in boreholes, a subaquatic DEM generated from unmanned aerial system (UAS) photogrammetry, terrestrial laser scan measurements of snow depth, geophysical ground investigations and automatic time-lapse photography. From this combination of data sources together with observations in the field, an interesting sequence of geomorphologic processes is established at Flüelapass. As a result we show how mass wasting processes can initiate the genesis and long-term conservation of ice-rich permafrost at the base of a talus slope.

Evaluation of the use of LIDAR laser scanner to map pruning wood in vineyards and its potential for management zones delineation

Vine vigour assessment has been a major concern of precision viticulture studies in order to identify areas of uniform vine performance within vineyards. Moreover, the counting and weighing of winter dormant canes is considered as the most informative measurement to indicate vine balance and is commonly performed manually by grape growers for management purposes. The main concern of this measurement is that it is time consuming and laborious and it cannot accommodate detailed sampling density. In the present study, the potential of using laser scanner technology as an automated, easy and rapid way to perform mapping of the winter pruning wood across the vineyard was investigated. The study was conducted during 2010 and 2011, in a one hectare commercial vineyard in central Greece, planted with cv. Agiorgitiko, a traditional Greek variety for the production of red wine. Parameters of topography, soil depth, soil texture, canopy properties (NDVI), yield, and grape quality were mapped and analysed in conjunction to winter canes weighing at pruning time. The mapping of the dormant canes was carried out using a 2D laser scanner sensor prior to pruning and manually measuring the pruning weight on a 10 × 20 m grid. Laser scanner measurements showed significant relationship in both 2010 and 2011 with pruning weight (r = 0.809 and r = 0.829 respectively, p < 0.001), yield and early season NDVI, showing the potential of using laser scanner measurements to assess variability in vine vigour within vineyards. These results suggest that laser scanners offer great promise to characterize within field variability in vine performance.

Scalp imaging techniques

Scalp imaging techniques are necessary tools for the trichological practice and for visualization of permeation, penetration and absorption processes into and through the scalp and for the research on drug delivery and toxicology.The present letter reviews different scalp imaging techniques and discusses their utility. Moreover, two different studies on scalp imaging techniques are presented in this letter: (1) scalp imaging with phototrichograms in combination with laser scanning microscopy, and (2) follicular measurements with cyanoacrylate surface replicas and light microscopy in combination with laser scanning microscopy.The experiments compare different methods for the determination of hair density on the scalp and different follicular measures. An average terminal hair density of 132 hairs cm−2 was found in 6 Caucasian volunteers and 135 hairs cm−2 in 6 Asian volunteers. The area of the follicular orifices accounts to 16.3% of the skin surface on average measured with laser scanning microscopy images. The potential volume of the follicular infundibulum was calculated based on the laser scanning measurements and is found to be 4.63 mm3 per cm2 skin on average. The experiments show that hair follicles are quantitatively relevant pathways and potential reservoirs for topically applied drugs and cosmetics.

Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

Effect of storms during drought on post‐wildfire recovery of channel sediment dynamics and habitat in the southern California chaparral, USA

AbstractCurrent global warming projections suggest a possible increase in wildfire and drought, augmenting the need to understand how drought following wildfire affects the recovery of stream channels in relation to sediment dynamics. We investigated post‐wildfire geomorphic responses caused by storms during a prolonged drought following the 2013 Springs Fire in southern California (USA), using multi‐temporal terrestrial laser scanning and detailed field measurements. After the fire, a dry‐season dry‐ravel sediment pulse contributed sand and small gravel to hillslope‐channel margins in Big Sycamore Creek and its tributaries. A small storm in WY 2014 generated sufficient flow to mobilize a portion of the sediment derived from the dry‐ravel pulse and deposited the fine sediment in the channel, totaling ~0.60 m3/m of volume per unit length of channel. The sediment deposit buried step‐pool habitat structure and reduced roughness by over 90%. These changes altered sediment transport characteristics of the bed material present before and after the storm; the ratio of available to critical shear stress (τo/τc) increased by five times. Storms during WY 2015 contributed additional fine sediment from tributaries and lower hillslopes and hyperconcentrated flow transported and deposited additional sediment in the channel. Together these sources delivered sediment on the order of six times that in 2014, further increasing τo/τc. These storms during multi‐year drought following wildfire transformed channel dynamics. The increased sediment transport capacity persisted during the drought period characterized by the longer residence time of relatively fine‐grained post‐fire channel sedimentation. This contrasts with wetter years, when post‐fire sediment is transported from the fluvial system during the same season as the post‐fire sediment pulse. Results of this short‐term study highlight the complex and substantial effects of multi‐year drought on geomorphic responses following wildfire. These responses influence pool habitat that is critical to longer‐term post‐wildfire riparian ecosystem recovery. Copyright © 2017 John Wiley &amp; Sons, Ltd.

New approach for monitoring historic and heritage buildings: Using terrestrial laser scanning and generalised Procrustes analysis

Numerous different techniques and instruments can be used for structural monitoring with different requirements producing different results. For instance, some techniques need to use embedded sensors inside the building, such as geotechnical sensors. However, this method cannot be used for historic and heritage buildings. Other methods can offer high quality, but with a low point density and require fixed stations and targets, such as total stations. In such a case, the location of deformation tends to be known, such as dams, bridges, high-rise buildings, and so forth. Nevertheless, this is not the case for historic and heritage buildings where each block could be subject to deformation. The challenge in such a case is to detect the deformation without any previous knowledge. The aim of this research is to develop a new approach to detect and localise unpredictable deformation. It is based on terrestrial laser scanner measurements and generalised Procrustes analysis techniques to determine deformation vectors, although boxing structure and F-tests are used to detect and localise deformation. In summary, after applying this approach, the whole concerned building is represented as parts, for each of them, the displacement vector and deformation probability are estimated. Validation experiments have shown the capability of the proposed method to detect and localise deformation with magnitude less than noise level in simulated data and of subcentimetre level for ranges up to 10 m in real scan data. Finally, the new approach has been applied to an English Historic site, Bellmanpark Limeklins.

Understanding the trigger for the LUSI mud volcano eruption from ground deformation signatures

Abstract The LUSI mud volcano in the sub-district of Porong, Sidoarjo, East Java, Indonesia started to erupt on 29 May 2006. An almost continuous eruption of a mixture of mud, water and gas has occurred around this area since this date. The eruption triggered vertical and horizontal ground deformation. From June 2006 to December 2010, 14 global positioning system campaigns were conducted to observe the ground deformation using c. 50 stations sparsely located up to 10 km from the eruption centre. Field observations of cracks, terrestrial laser scanning and geo-electrical measurements have also been used to infer the ground deformation signature around the LUSI mud volcano. More than 150 pairs of interferograms generated from 66 ALOS PALSAR images from June 2006 to December 2009 have also been used to study the ground deformation caused by the LUSI mud volcano. The LUSI mud eruption began only 200 m from where the Lapindo Inc. oil company was drilling for oil and gas. The drilling may have pierced a deeper high-pressure zone, causing an underground blow-out of the drillhole into a hydrofracture. Alternatively, the magnitude 6.3 Yogyakarta earthquake, which was located c. 275 km from the eruption site and occurred two days before the LUSI eruption, may have shaken the area sufficiently to cause the eruption by reactivating a fault in the region and liquefying the mud. These two hypotheses for triggering the mud volcano have been argued vehemently and still remain controversial. The ground deformation signatures provide important clues to understanding the trigger for the eruption and to solve this controversy. Co-seismic fault reactivation has its own typical ground deformation signature. This study used global positioning system and InSAR techniques, as well as field observations of cracks, terrestrial laser scanning and geo-electrical measurements, to determine the signature of ground deformation around the LUSI mud volcano and to explain the triggering mechanism.

An application of the ground laser scanning to recognise terrain surface deformation over a shallowly located underground excavation

In the Upper Silesian Coal Basin area, there are post-mining sites of shallow exploitation of metal ores and hard coal deposits that reveal discontinuous deformations. Most often, these areas are heavily urbanised and the appearing deformations may be dangerous to the existing building infrastructure. The work, described in this article, presents the results of the research, which aimed to rate the usefulness of laser scanning to recognize discontinuous deformations on surface areas located over shallow mining excavations. Two laser scanning measurements were taken over the course of a few months. The surface area images were compared to identify changes in its deformation, especially those areas located above mining excavations. The tests carried out by the laser scanning method showed that some of the identified discontinuous deformations could have been connected to the shallowly located mining excavations.

Terrestrial Laser Scanning-Based Deformation Analysis for Arch and Beam Structures

Nowadays, with the assistance of the high accuracy terrestrial laser scanning (TLS) measurement techniques, the mechanics analysis of structures could be better understood. This paper has a comparative analysis of arch and beam structures in terms of deformation behavior in loading experiments. The goal of this paper is to discover the potential value of the different structures in the architecture through the investigation of the anti-load capacity of the arch and beam structures. This paper is focused on the comparison of load-displacement relation between arch and beam with static load experiment, which is based on TLS techniques and surface analysis method. The innovation is that we try to reveal the partial area changing rules named “partial area analysis,” which is a new method to investigate the deformation behavior of structure. It is exposed that both arch and beam structures in the loading progress would suffer three stages, which are steady, developing, and fracture. Furthermore, considering the effect of pre-stress, steady stage would last longer, and developing and fracture stages would be hysteretic.

Comparison of 2 root surface area measurement methods: 3-dimensional laser scanning and cone-beam computed tomography.

PurposeThe aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement.Materials and MethodsThirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient (ICC) was used to assess intraobserver reliability.ResultsThe root surface area measurements (230.11±41.97 mm2) obtained using CBCT were slightly greater than those (229.31±42.46 mm2) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT.ConclusionThis study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.

An efficient 3D point cloud data denoising algorithm for ship block visual measurement

For the 3D point cloud data aquired by laser scanning measurement of ship block, an efficient denoising algorithm based on image and normal vector threshold judgement is proposed. Firstly, large scale noise points are eliminated using global threshold judgement based image, then Kuwahara filter algorithm is used for data smoothing and a denoising algorithm based on normal vector threshold judgement is proposed to eliminate noises point excluding ship manufacture sections. The experiment result demonstrates that not only the proposed denoising algorithm keeps key data points but also avoids bluring point cloud boundary and eliminates noise points effectively.

Improvements to the accuracy of prototype ship models measurement method using terrestrial laser scanner

Accuracy is a crucial requirement in the shipbuilding industry, especially during the design stage. The existence of errors in 3D prototype models can cause huge discrepancies when projected to full-scale objects. The ability to provide rapid and dense 3D data has made the terrestrial laser scanners (TLSs) a viable option in shipbuilding measurement. However, the numerous sources of systematic error that corrupt collected TLS data make a calibration procedure necessary. The requirement of laboratory with large number of targets to perform existing TLS calibration procedures make them unfeasible for most TLS users. Thus, this study has investigated the suitability of an on-site calibration method for application in high-accuracy shipbuilding. Two prototype boats were measured using a Faro Focus 3D scanner and close range photogrammetry was used for benchmarking purposes. By utilising four quantitative analyses, the results verify the ability of the developed calibration method to improve the accuracy of terrestrial laser scanner measurements in the field. With a relatively simple implementation, the developed calibration method is expected to be valuable for a wide variety of terrestrial laser scanner applications, especially the shipbuilding industry.

Method for estimating rice plant height without ground surface detection using laser scanner measurement

A method for estimating the height of rice plants, using three-dimensional laser range data from point clouds, is proposed and assessed. Rice plant height (H) is estimated using a reference position at the top of the rice plant, avoiding the need to determine the ground position. Field experiments were performed with a SICK LMS 200 laser scanner in 2013 and 2014 on a test field with five different planting geometries. Percentile analysis identified the closest percentile to the top of the rice plant (pt=1), with vertical distances at the first percentile unaffected by planting geometry. The plant bottom position was identified using three different percentile ranks (pb=95, pb =80, and pb =70). Relative vertical distances (rD) were computed from the difference between the top and bottom positions of the rice plant. These correlated well with measured H, with slopes greater than 1.0. A greater number of stems in 2014 led to steeper slopes. Estimated H was more accurate when plant bottom positions were closer to the ground surface, and the best results were obtained with pb=95 (r2>0.87; RMSE≈4 cm). Overall, H was typically 16.0 cm greater than rD with pb=95.

Lidar-based estimates of aboveground biomass in the continental US and Mexico using ground, airborne, and satellite observations

Existing national forest inventory plots, an airborne lidar scanning (ALS) system, and a space profiling lidar system (ICESat-GLAS) are used to generate circa 2005 estimates of total aboveground dry biomass (AGB) in forest strata, by state, in the continental United States (CONUS) and Mexico. The airborne lidar is used to link ground observations of AGB to space lidar measurements. Two sets of models are generated, the first relating ground estimates of AGB to airborne laser scanning (ALS) measurements and the second set relating ALS estimates of AGB (generated using the first model set) to GLAS measurements. GLAS then, is used as a sampling tool within a hybrid estimation framework to generate stratum-, state-, and national-level AGB estimates. A two-phase variance estimator is employed to quantify GLAS sampling variability and, additively, ALS-GLAS model variability in this current, three-phase (ground-ALS-space lidar) study. The model variance component characterizes the variability of the regression coefficients used to predict ALS-based estimates of biomass as a function of GLAS measurements. Three different types of predictive models are considered in CONUS to determine which produced biomass totals closest to ground-based national forest inventory estimates - (1) linear (LIN), (2) linear-no-intercept (LNI), and (3) log-linear. For CONUS at the national level, the GLAS LNI model estimate (23.95±0.45Gt AGB), agreed most closely with the US national forest inventory ground estimate, 24.17±0.06Gt, i.e., within 1%. The national biomass total based on linear ground-ALS and ALS-GLAS models (25.87±0.49Gt) overestimated the national ground-based estimate by 7.5%. The comparable log-linear model result (63.29±1.36Gt) overestimated ground results by 261%. All three national biomass GLAS estimates, LIN, LNI, and log-linear, are based on 241,718 pulses collected on 230 orbits. The US national forest inventory (ground) estimates are based on 119,414 ground plots. At the US state level, the average absolute value of the deviation of LNI GLAS estimates from the comparable ground estimate of total biomass was 18.8% (range: Oregon, −40.8% to North Dakota, 128.6%). Log-linear models produced gross overestimates in the continental US, i.e., >2.6x, and the use of this model to predict regional biomass using GLAS data in temperate, western hemisphere forests is not appropriate. The best model form, LNI, is used to produce biomass estimates in Mexico. The average biomass density in Mexican forests is 53.10±0.88t/ha, and the total biomass for the country, given a total forest area of 688,096km2, is 3.65±0.06Gt. In Mexico, our GLAS biomass total underestimated a 2005 FAO estimate (4.152Gt) by 12% and overestimated a 2007/8 radar study's figure (3.06Gt) by 19%.