• Korean Journal of Construction Engineering and Management
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• v.22 no.3
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• pp.40-51
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• 2021

MLS (Mobile Laser Scanning) which is a scanning method done by moving the LiDAR (Light Detection and Ranging) is widely employed to capture indoor PCD (Point Cloud Data) for floor plan generation in the AEC (Architecture, Engineering, and Construction) industry. The movement and rotation of LiDAR in the scanning phase cause deformation (i.e. skew) of PCD and impose a significant impact on quality of output. Thus, a de-skewing method is required to increase the accuracy of geometric representation. De-skewing methods which use position and pose information of LiDAR collected by IMU (Inertial Measurement Unit) have been mainly developed to refine the PCD. However, the existing methods have limitations on de-skewing PCD without IMU. In this study, a novel algorithm for de-skewing 2D PCD captured from MLS without IMU is presented. The algorithm de-skews PCD using scan matching between points captured from adjacent scan positions. Based on the comparison of the deskewed floor plan with the benchmark derived from TLS (Terrestrial Laser Scanning), the performance of proposed algorithm is verified by reducing the average mismatched area 49.82%. The result of this study shows that the accurate floor plan is generated by the de-skewing algorithm without IMU.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.4 s.38
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• pp.11-18
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• 2006

In this paper, airborne LiDAR data were evaluated in horizontal and vertical accuracy. By using zigzag scanning type of LiDAR, GCPs are not tested directly. So points around GCPs were used in this evaluation. Building corner points were made from LiDAR's building planar and compared with ground surveyed GCPs, in horizontal accuracy test. Its accuracy shows 19cm average and 21cm RMSE and 15 points were within 20cm among 16 points. In vertical accuracy test, 41 GCPs were used and it shows 11cm average and 14cm RMSE and 75% of GCPs were within 15cm. This could be a criterion in topographic map modification and basic geographic DB and 3D data construction using airborne LiDAR data.

• Journal of Cadastre & Land InformatiX
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• v.54 no.1
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• pp.5-17
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• 2024

In this study, we examined the applicability of UAV LiDAR for cadastral surveying and proposed the results. For this purpose, an experimental area was selected and point cloud data was created by scanning the terrain using UAV LiDAR. Since there is no comparative verification target in the forest area, the coordinates of the verification points were obtained by directly surveying the ridge and valley lines prescribed by the current law. Based on these points, the point cloud density within a 7cm radius was analyzed. As a result, an average of 46 point clouds were generated within a circle with a radius of 7 centimeters, which can build a more precise topography of the forest area, proving that precise cadastral surveying is possible. In the case of UAV LiDAR, it is expected that the boundaries of forest areas can be extracted more accurately and efficiently without the influence of trees compared to the existing cadastral survey method. This is expected to have many advantages in various fields that want to use it in the future, such as the creation of stereoscopic maps of forest areas and terrain modeling for disaster safety in the forest areas.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.571-581
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• 2020

Vegetation affects water level change and flow resistance in rivers and impacts waterway ecosystems as a whole. Therefore, it is important to have accurate information about the species, shape, and size of any river vegetation. However, it is not easy to collect full vegetation data on-site, so recent studies have attempted to obtain large amounts of vegetation data using terrestrial laser scanning (TLS). Also, due to the complex shape of vegetation, it is not easy to obtain accurate information about the canopy area, and there are limitations due to a complex range of variables. Therefore, the physical structure of vegetation was analyzed in this study by reconfiguring high-resolution point cloud data collected through 3-dimensional terrestrial laser scanning (3D TLS) in a voxel. Each physical structure was analyzed under three different conditions: a simple vegetation formation without leaves, a complete formation with leaves, and a patch-scale vegetation formation. In the raw data, the outlier and unnecessary data were filtered and removed by Statistical Outlier Removal (SOR), resulting in 17%, 26%, and 25% of data being removed, respectively. Also, vegetation volume by voxel size was reconfigured from post-processed point clouds and compared with vegetation volume; the analysis showed that the margin of error was 8%, 25%, and 63% for each condition, respectively. The larger the size of the target sample, the larger the error. The vegetation surface looked visually similar when resizing the voxel; however, the volume of the entire vegetation was susceptible to error.

• Korean Journal of Construction Engineering and Management
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• v.17 no.3
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• pp.32-42
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• 2016

In Korea, the absence of BIM use in existing civil structures and buildings is driving a demand for as-built BIM. As-built BIMs are often created using laser scanners that provide dense 3D point cloud data. Conventional static laser scanning approaches often suffer from limitations in their operability due to the difficulties in moving the equipment, the selection of scanning location, and the requirement of placing targets or extracting tie points for registration of each scanned point cloud. This paper aims at reducing the manual effort using a kinematic 3D laser scanning system based on graph-based simultaneous localization and mapping (SLAM) for continuous indoor mapping. The robotic platform carries three 2D laser scanners: the front scanner is mounted horizontally to compute the robot's trajectory and to build the SLAM graph; the other two scanners are mounted vertically to scan the profiles of surrounding environments. To reduce the accumulated error in the trajectory of the platform through loop closures, the graph-based SLAM system incorporates AdaBoost loop closure approach, which is particularly suitable for the developed multi-scanner system providing more features than the single-scanner system for training. We implemented the proposed method and evaluated it in two indoor test sites. Our experimental results show that the false positive rate was reduced by 13.6% and 7.9% for the two dataset. Finally, the 2D and 3D mapping results of the two test sites confirmed the effectiveness of the proposed graph-based SLAM.

• Journal of KIBIM
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• v.9 no.2
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• pp.21-28
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• 2019

Recently, many scan projects are gradually increasing for maintenance, construction. The scan data contains useful data, which can be generated in the target application from the facility, space. However, modeling the scan data required for the application requires a lot of cost. In example, the converting 3D point cloud obtained from scan data into 3D object is a time-consuming task, and the modeling task is still very manual. This research proposes Scan-to-Geometry Mapping Rule Definition (S2G-MD) which maps point cloud data to geometry for irregular building plane objects. The S2G-MD considers user use case variability. The method to define rules for mapping scan to geometry is proposed. This research supports the reverse engineering semi-automatic process for the building planar geometry from the user perspective.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.376-376
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• 2021

홍수와 같은 수문 재해를 예측하고 예방하기 위해서는 강우량을 정확하게 예측하는 것이 중요하다. 신뢰할 수 있는 수문재해 예보 시스템은 기존의 포인트 기반 우량계를 사용하여 달성 할 수 있는 것보다 강우량의 공간 분포를 관측할 수 있는 보다 효과적인 방법이 필요하다. 본 연구에서는 전파강수계 시스템과 다중 고도 관측 데이터를 이용하여 평균 강우를 추정하는 방법을 제시한다. 전파강수계는 K 밴드 이중 편파 기술을 사용하여 초단거리 관측을 수행하는 소형전파강수관측시스템이다. 평균 강우량을 추정하는 방법은 매우 짧은 관측 범위와 이중 편파 정보의 다중고도 평균 관측 개념을 기반으로 하며 관측 지역의 반사도와 비차등위상차의 고도별 평균값을 이용하여 추정한다. 제안 된 방법은 전파강수계의 관측 범위와 스캔 시간이 매우 짧기 때문에 강우 분포의 시공간적 변화가 낮다는 가정하에 개발되었다. 제안된 방법의 평가를 위해 핏게이지, 우량계 및 Parsivel disdrometer를 포함한 지상 장비와 비교하였다. 시험적용 결과 제안된 강우 추정 기법이 다양한 강우사상에 대해 강우강도를 잘 추정하는 것으로 확인되었다

• Journal of the Korea Computer Graphics Society
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• v.16 no.2
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• pp.29-37
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• 2010

In this paper, we present a novel deformation method for alleviating the asymmetry of a scanned 3D face considering facial features. To handle detailed areas of the face, we developed a new local 3D shape descriptor based on facial features and surface curvatures. Our shape descriptor can improve the accuracy when deforming a 3D face toward a symmetric configuration, because it provides accurate point pairing with respect to the plane of symmetry. In addition, we use point-based representation over all stages of symmetrization, which makes it much easier to support discrete processes. Finally, we performed a statistical analysis to assess subjects' preference for the symmetrized faces by our approach.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1505-1510
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• 2018

Product modeling technology for graphics is rapidly developing. And 3D data application and usability are increasing.modeling of product design is a very important factor in constructing. 3D modeling in product design takes a lot of production time. Recently, the reverse design method is very useful because of application of 3D data and shortening of production time. In this study, first, 3D point cloud and mesh data are generated using photographs based on image data. The second is to modify the design and the third is to make the prototype with the 3D printer. This product design and production process suggests the utilization and possibility of image data, the shortening of 3D modeling production time and efficient processes. Also, the product design process proposes a model of a new product development system to adapt to the production environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.38-45
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• 2016

The objective of this research is to develop a method of improving MEP facility management based on 3D reverse engineering. Recently, 3D image scanning-based reverse engineering has been implemented in the fields of architecture, construction and (manufacturing). In the case where there are many objects and the MEP system is complicated, 3D reverse engineering is applied in semiconductor factories, because facility maintenance works cause the 2D drawing to be different from the original one. The 3D point cloud data obtained from 3D image scanning contains accurate data and can increase the efficiency of complicated MEP facility maintenance works. For this purpose, the present research studied the technology trends and analyzed the process of 3D reverse engineering. Based on the results, a method of improving MEP facility management is established and its effects described.