• Journal of Korean Society of Disaster and Security
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• v.12 no.4
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• pp.53-61
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• 2019

Occurrences of debris flow are a serious danger to roads and residential located in mountainous areas and cause a lot of property loss. In this study, two basins were selected and spatial data were constructed to simulate the occurred debris flow from mountainous areas. The first basin was to use the Terrestrial LiDAR to scan the debris flow occurrence section and to build terrain data. For the second basin, use drones the sediment in the basin was photographed and DSM (Digital surface model) was generated. And to analyze the effect of the occurrence of debris flow on downstream side, FLO-2D, two-dimensional commercial model, was used to simulate the flow region of the debris flow. And it was compared with the sedimentation area of terrestrial LiDAR and drone measurement data.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.71-78
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• 2022

Recently, mountain disasters such as landslides and debris flows have flowed along mountain streams and hit residential areas and roads, increasing damage. In this study, in order to reduce damage and analyze causes of mountain disasters, field surveys and Terrestrial LiDAR terrain analysis were conducted targeting debris flow areas, and debris flow flow processes were simulated using FLO-2D and RAMM models, which are numerical models of debris flows. In addition, the debris flow deposition area was calculated and compared and analyzed with the actual occurrence section. The sedimentation area of the debris flow generation section of the LiDAR scan data was estimated to be approximately 21,336 ㎡, and was analyzed to be 20,425 ㎡ in the FLO-2D simulation and 19,275 ㎡ in the case of the RAMMS model. The constructed topographical data can be used as basic data to secure the safety of disaster risk areas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.323-328
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• 2019

In order to construct 3D geospatial information about the terrain, current measurement using a total station, remote sensing, GNSS(Global Navigation Satellite System) have been used. However, ground survey and GNSS survey have time and economic disadvantages because they have to be surveyed directly in the field. In case of using aerial photographs and satellite images, these methods have the disadvantage that it is difficult to obtain the three-dimensional shape of the terrain. The terrestrial LiDAR can acquire 3D information of X, Y, Z coordinate and shape obtained by scanning innumerable laser pulses at densely spaced intervals on the surface of the object to be observed at high density, and the processing can also be automated. In this study, terrestrial LiDAR was used to analyze slope displacement. Study area slopes were selected and data were acquired using LiDAR in 2016 and 2017. Data processing has been used to generate slope cross section and slope data, and the overlay analysis of the generated data identifies slope displacements within 0.1 m and suggests the possibility of using slope LiDAR on land to manage slopes. If periodic data acquisition and analysis is performed in the future, the method using the terrestrial lidar will contribute to effective risk slope management.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.29-35
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• 2013

Generally, Calculation of carbon dioxide absorption in the forest area is calculated using the information of the forest, such as tree height and DBH(Diameter of Breast Height). Tree height and DBH of these are obtained using the remote sensing data such as imagery and information of local forest survey. However, Mixed forest with a high proportion of field survey to lower the accuracy of forest information. In this study, vertical structure of the tree were identified by applying region growing method based on the slope using LiDAR data and height and number of the tree were identified by applying extracting top of the tree algorithm. Through the vertex tree extraction algorithm to identify height of tree and the number of individuals, substitute this for the DBH relation formula which is drawn from data through field surveys. In this, a quantitative calculation of carbon dioxide absorption were able to calculate the basic data. Also, carbon dioxide absorption of three type trees were calculated and average per unit area of carbon dioxide absorption were able to estimate.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.2
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• pp.48-58
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• 2022

This study tried to assess the applicability of a hand-held LiDAR for measuring the geometric structures of forest trees including diameters at a breast height(DBH) and tree height(H). A traditional method using tapelines was conducted to analyze the accuracy of the LiDAR instrument in the Taebaeksan national park in South Korea. Four statistical indices which are bias, root mean square error, mean absolute error, and correlation coefficient were employed to compare the measurements by the LiDAR instrument and traditional method. The DBHs from the LiDAR were very similar to those from the traditional method. And it indicated that the LiDAR is sufficient to be a alternative of a traditional method. However, there was a limitation in assessing the accuracy of LiDAR for measuring tree height by comparing the measurements by observer's eyes since they included different error sources. Further study is needed to assess the accuracy of LiDAR instrument for tree height through more reliable measurements.

• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.849-858
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• 2023

Investigating disaster sites such as earthquakes and landslides involves significant risks due to potential secondary disasters like facility collapse. In situations where direct access is challenging, there is a need to develop methods for safely acquiring high-precision 3D disaster information using light detection and ranging (LiDAR) equipped drone survey systems. In this study, the feasibility of using drone LiDAR in disaster scenarios was examined, focusing on the collapse accident at Jeongja Bridge in Bundang-gu, Seongnam City, in April 2023. High-density point clouds for the accident bridge were collected, and the bridge's 3D terrain information was reconstructed and compared to the measurement performance of 10 ground control points. The results showed horizontal and vertical root mean square error values of 0.032 m and 0.055 m, respectively. Additionally, when compared to a point cloud generated using ground LiDAR for the same target area, a vertical difference of approximately 0.08 m was observed, but overall shapes showed minimal discrepancies. Moreover, in terms of overall data acquisition and processing time, drone LiDAR was found to be more efficient than ground LiDAR. Therefore, the use of drone LiDAR in disaster sites with significant risks allows for safe and rapid onsite investigations.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.06a
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• pp.310-317
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• 2008

Although aerial LiDAR had been launched commercially several years ago, it is still difficult to study data acquisition conditions and effects with various datasets because of its acquisition cost. Thus, this research was performed to study data acquisition conditions and effects with virtually various datasets. For this research, 3D tree models and forest stand models were built to represent graded tree sizes and tree plantation densities. Also, a variable aerial LiDAR acquisition model was developed. Then, through controlling flight height parameter, one of the data acquisition parameters, virtual datasets were collected for various data acquisition densities. From those datasets, forest canopy volumes and maximum tree heights were estimated and the estimated results were compared. As the results, the estimated is getting closer to the expected during the data acquisition density increase. This research would be helpful to perform further studios on relations between forest inventory accuracy and LiDAR cost.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.2
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• pp.63-68
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• 2010

In this study, subject areas with different topographic feature were selected for the purpose of measuring the slope terrain by setting Terrestrial LiDAR in different places. And the slope terrain was analyzed based on three-dimensional raw data obtained through the measurement of slope terrain. With DEM data obtained from five measurement instances with 5mm of scan interval by setting Terrestrial LiDAR on the site 30m away straight from the slope terrain consisting of asphalt, rock, soil, and plants, the slope terrain was analyzed according to topographic feature. In addition, in consideration of changes in setting location that might affect the measured result, this study reviewed the accuracy of measured data obtained from different measurement areas.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.389-397
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• 2006

The purpose of the present paper is to offer an analysis of LiDAR data processing and three dimensional terrain for Geographic Information System (CIS) applications. Generally, LiDAR survey is the method which obtains quantitative and qualitative information of the terrain using airborne laser scanning (ALS). We will get a most topographic data at a Triangular Irregular Network (TIN), Digital Surface Model (DSM) and Digital Elevation Model (DEM) using LiDAR data. We examined many factors such as visibility, hillshade, aspect and slope using DEM and DSM. The analyzing results obtained from each item are thought to be regarded as leading factors in the terrain analysis. It is to be hoped that LiDAR survey will contribute a new approach to the terrain analysis.

• Economic and Environmental Geology
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• v.52 no.3
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• pp.231-241
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• 2019

Kinematic analysis determines the stability of rock slope by analyzing the relationship between the slope face orientation and the discontinuity orientation. In this study, terrestrial LiDAR was used to obtain a large amount of discontinuity orientation data and then, the probabilistic characteristics of the orientation data obtained using terrestrial LiDAR were analyzed. Subsequently, the probabilistic kinematic analysis was carried out using the discontinuity orientations generated randomly from Fisher function in Monte Carlo simulation. In addition, the probabilistic kinematic analysis was also performed using the actual orientation data obtained from the terrestrial LiDAR to compare their results. Consequently, the results of both probabilistic analyses showed similar results. Therefore, if sufficient orientation data are provided by other means such as terrestrial LiDAR, the probabilistic analysis will show reasonable results using the actual field data without randomly generating orientation data. In addition, the deterministic kinematic analysis was also carried out using representative orientation of discontinuity sets. The analysis result of the probabilistic analysis showed similar results with the deterministic analysis because the dispersion of the discontinuity orientations in a joint set is not large.