• 제목, 요약, 키워드: Terrestrial LiDAR

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Comparative Accuracy of Terrestrial LiDAR and Unmanned Aerial Vehicles for 3D Modeling of Cultural Properties (문화재 3차원 모델링을 위한 지상 LiDAR와 UAV 정확도 비교 연구)

  • Lee, Ho-Jin;Cho, Gi-Sung
    • Journal of Cadastre & Land InformatiX
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    • v.47 no.1
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    • pp.179-190
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    • 2017
  • A terrestrial LiDAR survey was conducted and unmanned aerial vehicle(UAV) images were taken for target cultural properties to present the utilization measures of terrestrial LiDAR and UAV in three-dimensional modeling of cultural properties for the identification of the status and restoration of cultural properties. Then the accuracy of the point clouds generated through this process was compared, an overlap analysis of the 3D model was conducted, and a convergence model was created. According to the results, the modeling with terrestrial LiDAR is more appropriate for precise survey because 3D modeling for the detection of displacement and deformation of cultural properties requires an accuracy of mm units. And UAV model has limitation as the impossibility of detailed expression of parts with sharp unevenness such as cracks of bricks. However, it is found that the UAV model has a wide range of modeling and has the advantage of modeling of real cultural properties. Finally, the convergence model created in this study using the advantages of the terrestrial LiDAR model and the UAV model could be efficiently utilized for the basic data development of cultural properties.

Tunnel Reverse Engineering Using Terrestrial LiDAR (지상LiDAR를 이용한 터널의 Reverse Engineering)

  • Cho, Hyung Sig;Sohn, Hong Gyoo;Kim, Jong Suk;Lee, Suk Kun
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.6D
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    • pp.931-936
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    • 2008
  • Surveying by using terrestrial LiDAR(Light Detection And Ranging) is more rapid than by using total station which enables tunnel section profile surveying to be done in suitable time and minimize centerline error, occurrence of overcut and undercut. Therefore, utilization of terrestrial LiDAR has increased more and more in section profile survey and measurement field Moreover, studies of terrestrial LiDAR for accurate and efficient utilization is now ongoing vigorously. Average end area formula, which was generally used to calculate overcut and undercut, was compared with existing methods such as total station survey and photogrammetry. However, there are no criteria of spacing distance for calculating overcut and undercut through terrestrial LiDAR surveying which can acquire 3D information of whole tunnel. This research performed reverse engineering to decide optimal spacing distance when surveying tunnel section profile by comparing whole tunnel volume and tunnel volume in difference spacing distance. This result was utilized to produce CAD drawing for the test tunnel site where there is no design drawings. In addition to this, efficiency of LiDAR and accuracy of CAD drawing was compared with targetless total station surveying of tunnel section profile. Finally, error analysis of target coordinate's accuracy and incidence angle was done in order to verify the accuracy of terrestrial LiDAR technology.

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Application of Terrestrial LiDAR to Monitor Unstable Blocks in Rock Slope (암반사면 위험블록 모니터링을 위한 지상 LiDAR의 활용)

  • Song, Young-Suk;Lee, Choon-Oh;Oh, Hyun-Joo;Pak, Jun-Hou
    • The Journal of Engineering Geology
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    • v.29 no.3
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    • pp.251-264
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    • 2019
  • The displacement monitoring of unstable block at the rock slope located in the Cheonbuldong valley of Seoraksan National Park was carried out using Terrestrial LiDAR. The rock slopes around Guimyeonam and Oryeon waterfall where rockfall has occurred or is expected to occur are selected as the monitoring section. The displacement monitoring of unstable block at the rock slope in the selected area was performed 5 times for about 7 months using Terrestrial LiDAR. As a result of analyzing the displacement based on the Terrestrial LiDAR scanning, the error of displacement was highly influenced by the interpolation of the obstruction section and the difference of plants growth. To minimize the external influences causing the error, the displacement of unstable block should be detected at the real scanning point. As the result of analyzing the displacement of unstable rock at the rock slope using the Terrestrial LiDAR data, the amount of displacement was very small. Because the amount of displacement was less than the range of error, it was difficult to judge the actual displacement occurred. Meanwhile, it is important to select a section without vegetation to monitor the precise displacement of unstable rock at the rock slope using Terrestrial LiDAR. Also, the PointCloud removal and the mesh model analysis in a vegetation section were the most important work to secure reliability of data.

3D Reconstruction of Structure Fusion-Based on UAS and Terrestrial LiDAR (UAS 및 지상 LiDAR 융합기반 건축물의 3D 재현)

  • Han, Seung-Hee;Kang, Joon-Oh;Oh, Seong-Jong;Lee, Yong-Chang
    • Journal of Urban Science
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    • v.7 no.2
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    • pp.53-60
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    • 2018
  • Digital Twin is a technology that creates a photocopy of real-world objects on a computer and analyzes the past and present operational status by fusing the structure, context, and operation of various physical systems with property information, and predicts the future society's countermeasures. In particular, 3D rendering technology (UAS, LiDAR, GNSS, etc.) is a core technology in digital twin. so, the research and application are actively performed in the industry in recent years. However, UAS (Unmanned Aerial System) and LiDAR (Light Detection And Ranging) have to be solved by compensating blind spot which is not reconstructed according to the object shape. In addition, the terrestrial LiDAR can acquire the point cloud of the object more precisely and quickly at a short distance, but a blind spot is generated at the upper part of the object, thereby imposing restrictions on the forward digital twin modeling. The UAS is capable of modeling a specific range of objects with high accuracy by using high resolution images at low altitudes, and has the advantage of generating a high density point group based on SfM (Structure-from-Motion) image analysis technology. However, It is relatively far from the target LiDAR than the terrestrial LiDAR, and it takes time to analyze the image. In particular, it is necessary to reduce the accuracy of the side part and compensate the blind spot. By re-optimizing it after fusion with UAS and Terrestrial LiDAR, the residual error of each modeling method was compensated and the mutual correction result was obtained. The accuracy of fusion-based 3D model is less than 1cm and it is expected to be useful for digital twin construction.

A Study of Monitoring in Slopes of High Collapse Risk Using Terrestrial LiDAR (지상 LiDAR를 이용한 위험관리사면의 변위 모니터링)

  • Park, Jae-Kook
    • Journal of the Korean Society of Hazard Mitigation
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    • v.10 no.6
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    • pp.45-52
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    • 2010
  • One of the ways to minimize damage by a slope collapse is to set up preventive measures in advance by measuring displacements in a slope and predicting a collapse. There have been many different technologies developed to predict a collapse with diverse measuring equipment. Especially recently, attempts have been made to utilize terrestrial LiDAR, a high-tech imaging equipment to measure displacements on a scope. Terrestrial LiDAR generates three-dimensional information about an object with millimeter-level accuracy from hundreds of meters away and has been used in an array of fields including restoration of cultural assets, three-dimensional modeling, and making of topographic maps. In recent years, it has been used to measure displacements in structure as well. This study monitored displacements in slopes of high collapse risk with terrestrial LiDAR. As a result, it was able to confirm the applicability of terrestrial LiDAR to the field, and proposed monitoring methods.

Terrestrial LiDAR Measurements and Analysis of Topographical Changes on Malipo Beach (지상 LiDAR를 이용한 만리포 해변 정밀 지형측량 및 지형 변화 분석)

  • Shim, Jae-Seol;Kim, Jin-Ah;Park, Han-San;Kim, Seon-Jeong
    • Ocean and Polar Research
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    • v.32 no.1
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    • pp.73-84
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    • 2010
  • A terrestrial LiDAR was used to acquire precise and high-resolution topographical information of Malipo beach, Korea. Terrestrial LiDAR and RTK-DGPS (VRS) were mounted on top of a survey vehicle and used to scan 20 times stop-and-go method with 250 m spacing intervals at ebb tides. In total, 7 measurements were made periodically from 2008 to 2009 and after each beach replenishment event. We carried out GIS-based 3D spatial analysis such as slope and volume calculations in order to assess topographical changes over time. In relation to beach replenishment, comparative analysis of each volume change revealed them to be similar. This result indicates that the terrestrial LiDAR measurements are accurate and can be used to analyze temporal topographical changes. In conclusion, the methodology employed in this study can be used efficiently to exercise coastal management through monitoring and analyzing beach process such as erosion and deposition.

Experiment of Computation of Ground Cutting Volume Using Terrestrial LiDAR Data (지상 LiDAR 자료의 절토량 산정 실험)

  • Kim, Jong-Hwa;Pyeon, Mu-Wook;Kim, Sang-Kuk;Hwang, Yeon-Soo;Kang, Nam-Gi
    • Journal of Korean Society for Geospatial Information Science
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    • v.17 no.2
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    • pp.11-17
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    • 2009
  • Terrestrial LiDAR can measure high capacity 3D-topography coordinates and try to apply to various public works such as tunnel surveying, facility deformation surveying. This experiment is about how to calculate ground cutting volume because the stage of the earth work spend lots of money and time among civil engineering works. Surveying cutting area using Terrestrial LiDAR and then calculating cutting area in planned area comparing sectional plan before construction and planned section and LiDAR data. Also, the values of the calculating ground cutting volume by three different resolution LiDAR has are compared and analyzed.

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Construction of 3D Spatial Information of Vertical Structure by Combining UAS and Terrestrial LiDAR (UAS와 지상 LiDAR 조합에 의한 수직 구조물의 3차원 공간정보 구축)

  • Kang, Joon-Oh;Lee, Yong-Chang
    • Journal of Cadastre & Land InformatiX
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    • v.49 no.2
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    • pp.57-66
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    • 2019
  • Recently, as a part of the production of spatial information by smart cities, three-dimensional reproduction of structures for reverse engineering has been attracting attention. In particular, terrestrial LiDAR is mainly used for 3D reproduction of structures, and 3D reproduction research by UAS has been actively conducted. However, both technologies produce blind spots due to the shooting angle. This study deals with vertical structures. 3D model implemented through SfM-based image analysis technology using UAS and reproducibility and effectiveness of 3D models by terrestrial LiDAR-based laser scanning are examined. In addition, two 3D models are merged and reviewed to complement the blind spot. For this purpose, UAS based image is acquired for artificial rock wall, VCP and check point are set through GNSS equipment and total station, and 3D model of structure is reproduced by using SfM based image analysis technology. In addition, Through 3D LiDAR scanning, the 3D point cloud of the structure was acquired, and the accuracy of reproduction and completeness of the 3D model based on the checkpoint were compared and reviewed with the UAS-based image analysis results. In particular, accuracy and realistic reproducibility were verified through a combination of point cloud constructed from UAS and terrestrial LiDAR. The results show that UAS - based image analysis is superior in accuracy and 3D model completeness and It is confirmed that accuracy improves with the combination of two methods. As a result of this study, it is expected that UAS and terrestrial LiDAR laser scanning combination can complement and reproduce precise three-dimensional model of vertical structure, so it can be effectively used for spatial information construction, safety diagnosis and maintenance management.

Evaluation for Earthwork Slope Safety Using Terrestrial LiDAR (지상 LiDAR를 이용한 토공 사면의 안정성 평가)

  • Kim, Hee-Gyoo;Roh, Tae-Ho
    • Journal of the Korean Association of Geographic Information Studies
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    • v.17 no.3
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    • pp.82-92
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    • 2014
  • The ratio of using soil as the main material in construction is quite numerous, and it covers many parts in forms and bases of the structure. Thus, the earthwork forms many structures for social infrastructure, and the stability of these structures is most crucial when completed than under construction. This study executed a field experiment to evaluate the accuracy and utility of the slope, which is an important part in earthwork, when terrestrial LiDAR is obtained, and the results are as follow. First, as the result of the observation using Total Station and terrestrial LiDAR, the horizontal error RMSE was ${\pm}2.2cm$, and the vertical error RMSE was ${\pm}3.0cm$. As the result of the comparison between the errors and permissible range of public surveying regulation, it sufficiently secure the accuracy. Also, the extraction of the check section, which covers the most important part among the stability checks could be scientifically and rationally processed, and these extraction results are expected to be provided as important basic materials for the earthwork slop stability evaluation.