scholarly journals A STUDY ABOUT TERRESTRIAL LASER SCANNING FOR RECONSTRUCTION OF PRECAST CONCRETE TO SUPPORT QLASSIC ASSESSMENT

2016 ◽  
Vol XLII-4/W1 ◽  
pp. 135-140 ◽  
Author(s):  
M. A. Aziz ◽  
K. M. Idris ◽  
Z. Majid ◽  
M. F. M. Ariff ◽  
A. R. Yusoff ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Precast Concrete ◽  
Terrestrial Laser Scanning ◽  
Assessment System ◽  
Construction Productivity ◽  
Measuring Tape ◽  
Real Time Applications ◽  
White Target ◽  
Precast Elements

Nowadays, terrestrial laser scanning shows the potential to improve construction productivity by measuring the objects changes using real-time applications. This paper presents the process of implementation of an efficient framework for precast concrete using terrestrial laser scanning that enables contractors to acquire accurate data and support Quality Assessment System in Construction (QLASSIC). Leica Scanstation C10, black/white target, Autodesk Revit and Cyclone software were used in this study. The results were compared with the dimensional of based model precast concrete given by the company as a reference with the AutoDesk Revit model from the terrestrial laser scanning data and conventional method (measuring tape). To support QLASSIC, the tolerance dimensions of cast in-situ & precast elements is +10mm / -5mm. The results showed that the root mean square error for a Revit model is 2.972mm while using measuring tape is 13.687mm. The accuracy showed that terrestrial laser scanning has an advantage in construction jobs to support QLASSIC.

scholarly journals TLS and SfM Approach for Bulk Density Determination of Excavated Heterogeneous Raw Materials

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 174 ◽  
Author(s):  
Peter Blistan ◽  
Stanislav Jacko ◽  
Ľudovít Kovanič ◽  
Julián Kondela ◽  
Katarína Pukanská ◽  
...  
Keyword(s):  
Bulk Density ◽  
Laser Scanning ◽  
Large Scale ◽  
Raw Materials ◽  
Terrestrial Laser Scanning ◽  
Mineral Resources ◽  
Point Clouds ◽  
Raw Material

A frequently recurring problem in the extraction of mineral resources (especially heterogeneous mineral resources) is the rapid operative determination of the extracted quantity of raw material in a surface quarry. This paper deals with testing and analyzing the possibility of using unconventional methods such as digital close-range photogrammetry and terrestrial laser scanning in the process of determining the bulk density of raw material under in situ conditions. A model example of a heterogeneous deposit is the perlite deposit Lehôtka pod Brehmi (Slovakia). Classical laboratory methods for determining bulk density were used to verify the results of the in situ method of bulk density determination. Two large-scale samples (probes) with an approximate volume of 7 m3 and 9 m3 were realized in situ. 6 point samples (LITH) were taken for laboratory determination. By terrestrial laser scanning (TLS) measurement from 2 scanning stations, point clouds with approximately 163,000/143,000 points were obtained for each probe. For Structure-from-Motion (SfM) photogrammetry, 49/55 images were acquired for both probes, with final point clouds containing approximately 155,000/141,000 points. Subsequently, the bulk densities of the bulk samples were determined by the calculation from in situ measurements by TLS and SfM photogrammetry. Comparison of results of the field in situ measurements (1841 kg∙m−3) and laboratory measurements (1756 kg∙m−3) showed only a 4.5% difference in results between the two methods for determining the density of heterogeneous raw materials, confirming the accuracy of the used in situ methods. For the determination of the loosening coefficient, the material from both large-scale samples was transferred on a horizontal surface. Their volumes were determined by TLS. The loosening coefficient for the raw material of 1.38 was calculated from the resulting values.

Terrestrial laser scanning and structure-from-motion photogrammetry concordance analysis for describing the surface layer of gravel beds

2019 ◽  
Vol 43 (2) ◽  
pp. 260-281 ◽  
Author(s):  
Andrew J Neverman ◽  
Ian C Fuller ◽  
Jon N Procter ◽  
Russell G Death
Keyword(s):  
Surface Layer ◽  
Structure From Motion ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Survey Method ◽  
Gravel Beds ◽  
Non Invasive ◽  
Sampling Biases

Terrestrial laser scanning (TLS) and structure-from-motion photogrammetry (SfMp) offer rapid, non-invasive surveying of in situ gravels. Numerous studies have used the point clouds derived from TLS or SfMp to quantify surface layer characteristics, but direct comparison of the methods for grain-scale analysis has received relatively little attention to date. Comparing equivalent products of different data capture methods is critical as differences in errors and sampling biases between the two methods may produce different outputs, effecting further analysis. The sampling biases and errors related to SfMp and TLS lead to differences in the point clouds produced by each method. The metrics derived from the point clouds are therefore likely to differ, potentially leading to different inputs for entrainment threshold models, different trends in surface layer development being identified and different trajectories for physical processes and habitat quality being predicted. This paper provides a direct comparison between TLS and SfMp surveys of an exposed gravel bar for three different survey periods following inundation and reworking of the bar surface during high flow events. The point clouds derived from the two methods are used to describe changes in the character of the surface layer between bar inundation events, and comparisons are made with descriptions derived from conventional pebble counts. The results found differences in the metrics derived using each method do exist, but the grid resolution used to detrend the surfaces and identify spatial variations in surface layer characteristics had a greater impact than survey method. Further research is required to understand the significance of these variations for quantifying surface texture and structure and for predicting entrainment thresholds and transport rates.

scholarly journals Evaluación de elementos premoldeados de hormigón utilizados en instalaciones de crianza de ganado porcino en ambiente agresivo. Recomendaciones de fabricación

2013 ◽  
Vol 3 (2) ◽  
pp. 140-148
Author(s):  
M. Positieri ◽  
C. Baronetto ◽  
B. Raggiotti
Keyword(s):  
Ultrasonic Wave ◽  
Precast Concrete ◽  
Capillary Absorption ◽  
Aggressive Environment ◽  
Compression Speed ◽  
Intensive Rearing ◽  
Service Conditions ◽  
Precast Elements ◽  
Concrete Elements

RESUMENLas modernas instalaciones destinadas a la crianza intensiva de ganado porcino se construyen con elementos premoldeados de hormigón ensamblados in situ en grandes superficies techadas; están sujetas a un ambiente agresivo por los excrementos y vapores que el ganado porcino produce, produciéndose un recambio prematuro de piezas por la escasa durabilidad de las mismas. El trabajo presenta los resultados del estudio realizado sobre elementos premoldeados de hormigón (sin uso) que conforman la estructura, con el objetivo de verificar su comportamiento en las condiciones de servicio y realizar recomendaciones para asegurar su correcto desempeño. Se extrajeron testigos de las piezas y se midieron la resistencia a compresión, velocidad de pasaje de onda ultrasónica, absorción capilar, absorción y permeabilidad al aire. Los resultados obtenidos permiten calificar al hormigón entre regular y bueno y se presentan las recomendaciones que deberían considerarse al fabricar los elementos premoldeados para asegurar su durabilidad.Palabras Clave: hormigón; premoldeados; durabilidad; calidad; testigos.ABSTRACTThe modern installations for the intensive rearing of pigs are constructed based on precast concrete elements that are assembled on site in large areas covered and which are subject to an aggressive environment and in the feces they produce vapors, causing a premature replacement of parts by the low durability of the same. The paper presents the results of a study on precast concrete (unworn) that make up the structure in order to verify its performance in service conditions and make recommendations to assure its correct performance. Witnesses were extracted from the parts and measured the resistance to compression, speed of passage of the ultrasonic wave, capillary absorption, absorption and permeability to air. The results obtained allow us to qualify to the concrete between regular and good and presents the recommendations should be considered when manufacturing the precast elements to ensure their durability.Keywords: concrete; precast; durability; quality; witnesses.

Evolution of a natural debris flow: In situ measurements of flow dynamics, video imagery, and terrestrial laser scanning

Geology ◽  
2010 ◽  
Vol 38 (8) ◽  
pp. 735-738 ◽  
Author(s):  
Scott W. McCoy ◽  
Jason W. Kean ◽  
Jeffrey A. Coe ◽  
Dennis M. Staley ◽  
Thad A. Wasklewicz ◽  
...  
Keyword(s):  
Debris Flow ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
In Situ Measurements ◽  
Flow Dynamics ◽  
Video Imagery

scholarly journals Retrieving Corn Canopy Leaf Area Index from Multitemporal Landsat Imagery and Terrestrial LiDAR Data

2019 ◽  
Vol 11 (5) ◽  
pp. 572 ◽  
Author(s):  
Wei Su ◽  
Jianxi Huang ◽  
Desheng Liu ◽  
Mingzheng Zhang
Keyword(s):  
Laser Scanning ◽  
Landsat Imagery ◽  
Terrestrial Laser Scanning ◽  
Distribution Functions ◽  
Leaf Angle ◽  
Angle Distribution ◽  
Area Index ◽  
Leaf Angle Distribution ◽  
Modis Lai

Leaf angle is a critical structural parameter for retrieving canopy leaf area index (LAI) using the PROSAIL model. However, the traditional method using default leaf angle distribution in the PROSAIL model does not capture the phenological dynamics of canopy growth. This study presents a LAI retrieval method for corn canopies using PROSAIL model with leaf angle distribution functions referred from terrestrial laser scanning points at four phenological stages during the growing season. Specifically, four inferred maximum-probability leaf angles were used in the Campbell ellipsoid leaf angle distribution function of PROSAIL. A Lookup table (LUT) is generated by running the PROSAIL model with inferred leaf angles, and the cost function is minimized to retrieve LAI. The results show that the leaf angle distribution functions are different for the corn plants at different phenological growing stages, and the incorporation of derived specific corn leaf angle distribution functions distribute the improvement of LAI retrieval using the PROSAIL model. This validation is done using in-situ LAI measurements and MODIS LAI in Baoding City, Hebei Province, China, and compared with the LAI retrieved using default leaf angle distribution function at the same time. The root-mean-square error (RMSE) between the retrieved LAI on 4 September 2014, using the modified PROSAIL model and the in-situ measured LAI was 0.31 m2/m2, with a strong and significant correlation (R2 = 0.82, residual range = 0 to 0.6 m2/m2, p < 0.001). Comparatively, the accuracy of LAI retrieved results using default leaf angle distribution is lower, the RMSE of which is 0.56 with R2 = 0.76 and residual range = 0 to 1.0 m2/m2, p < 0.001. This validation reveals that the introduction of inferred leaf angle distributions from TLS data points can improve the LAI retrieval accuracy using the PROSAIL model. Moreover, the comparations of LAI retrieval results on 10 July, 26 July, 19 August and 4 September with default and inferred corn leaf angle distribution functions are all compared with MODIS LAI products in the whole study area. This validation reveals that improvement exists in a wide spatial range and temporal range. All the comparisons demonstrate the potential of the modified PROSAIL model for retrieving corn canopy LAI from Landsat imagery by inferring leaf orientation from terrestrial laser scanning data.

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