• Title, Summary, Keyword: Photogrammetry

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Update of Digital Map by using The Terrestrial LiDAR Data and Modified RANSAC (수정된 RANSAC 알고리즘과 지상라이다 데이터를 이용한 수치지도 건물레이어 갱신)

  • Kim, Sang Min;Jung, Jae Hoon;Lee, Jae Bin;Heo, Joon;Hong, Sung Chul;Cho, Hyoung Sig
    • Journal of Korean Society for Geospatial Information System
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    • v.22 no.4
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    • pp.3-11
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    • 2014
  • Recently, rapid urbanization has necessitated continuous updates in digital map to provide the latest and accurate information for users. However, conventional aerial photogrammetry has some restrictions on periodic updates of small areas due to high cost, and as-built drawing also brings some problems with maintaining quality. Alternatively, this paper proposes a scheme for efficient and accurate update of digital map using point cloud data acquired by Terrestrial Laser Scanner (TLS). Initially, from the whole point cloud data, the building sides are extracted and projected onto a 2D image to trace out the 2D building footprints. In order to register the footprint extractions on the digital map, 2D Affine model is used. For Affine parameter estimation, the centroids of each footprint groups are randomly chosen and matched by means of a modified RANSAC algorithm. Based on proposed algorithm, the experimental results showed that it is possible to renew digital map using building footprint extracted from TLS data.

Application of Smartphone Camera Calibration for Close-Range Digital Photogrammetry (근접수치사진측량을 위한 스마트폰 카메라 검보정)

  • Yun, MyungHyun;Yu, Yeon;Choi, Chuluong;Park, Jinwoo
    • Korean Journal of Remote Sensing
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    • v.30 no.1
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    • pp.149-160
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    • 2014
  • Recently studies on application development and utilization using sensors and devices embedded in smartphones have flourished at home and abroad. This study aimed to analyze the accuracy of the images of smartphone to determine three-dimension position of close objects prior to the development of photogrammetric system applying smartphone and evaluate the feasibility to use. First of all, camera calibration was conducted on autofocus and infinite focus. Regarding camera calibration distortion model with balance system and unbalance system was used for the decision of lens distortion coefficient, the results of calibration on 16 types of projects showed that all cases were in RMS error by less than 1 mm from bundle adjustment. Also in terms of autofocus and infinite focus on S and S2 model, the pattern of distorted curve was almost the same, so it could be judged that change in distortion pattern according to focus mode is very little. The result comparison according to autofocus and infinite focus and the result comparison according to a software used for multi-image processing showed that all cases were in standard deviation less than ${\pm}3$ mm. It is judged that there is little result difference between focus mode and determination of three-dimension position by distortion model. Lastly the checkpoint performance by total station was fixed as most probable value and the checkpoint performance determined by each project was fixed as observed value to calculate statistics on residual of individual methods. The result showed that all projects had relatively large errors in the direction of Y, the direction of object distance compared to the direction of X and Z. Like above, in terms of accuracy for determination of three-dimension position for a close object, the feasibility to use smartphone camera would be enough.

Comparison of Topographic Surveying Results using a Fixed-wing and a Popular Rotary-wing Unmanned Aerial Vehicle (Drone) (고정익 무인항공기(드론)와 보급형 회전익 무인항공기를 이용한 지형측량 결과의 비교)

  • Lee, Sungjae;Choi, Yosoon
    • Tunnel and Underground Space
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    • v.26 no.1
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    • pp.24-31
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    • 2016
  • Recently, many studies have been conducted to use fixed-wing and rotary-wing unmanned aerial vehicles (UAVs, Drones) for topographic surveying in open-pit mines. Because the fixed-wing and rotary-wing UAVs have different characteristics such as flight height, speed, time and performance of mounted cameras, their results of topographic surveying at a same site need to be compared. This study selected a construction site in Yangsan-si, Gyeongsangnam-do, Korea as a study area and compared the topographic surveying results from a fixed-wing UAV (SenseFly eBee) and a popular rotary-wing UAV (DJI Phantom2 Vision+). As results of data processing for aerial photos taken from eBee and Phantom2 Vision+, orthomosaic images and digital surface models with about 4 cm grid spacing could be generated. Comparisons of the X, Y, Z-coordinates of 7 ground control points measured by differential global positioning system and those determined by eBee and Phantom2 Vision+ revealed that the root mean squared errors of X, Y, Z-coordinates were around 10 cm, respectively.

Availability Evaluation For Generation Orthoimage Using Photogrammetric UAV System (사진측량용 UAV 시스템을 이용한 정사영상 제작 및 활용성 평가)

  • Shin, Dongyoon;Han, Jihye;Jin, Yujin;Park, Jaeyoung;Jeong, Hohyun
    • Korean Journal of Remote Sensing
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    • v.32 no.3
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    • pp.275-285
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    • 2016
  • This study analyzes the accuracy of ortho imagery based on whether camera calibration performed or not, using an unmanned aerial vehicle which equipped smart camera. Photgrammetric UAV system application was developed and smart camera performed image triangulation, and then created image as ortho imagery. Image triangulation was performed depending on whether interior orientation (IO) parameters were considered or not, which determined at the camera calibration phase. As a result of the camera calibration, RMS error appeared 0.57 pixel, which is more accurate compared to the result of the previous study using non-metric camera. When IO parameters were considered in static experiment, the triangulation resulted in 2 pixel or less (RMSE), which is at least 200 % higher than when IO parameters were not considered. After generate ortho imagery, the accuracy is 89% higher when camera calibration are considered than when they are not considered. Therefore, smart camera has high potential to use as a payload for UAV system and is expected to be equipped on the current UAV system to function directly or indirectly.

Using Numerical Maps to Select Solar Panel Installation Sites no Expressway Slopes (수치지도를 이용한 고속국도 주변 태양광 패널 설치 대상지 선정)

  • Jung, Jaehoon;Kim, Byungil
    • Korean Journal of Construction Engineering and Management
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    • v.17 no.5
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    • pp.71-77
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    • 2016
  • Solar energy is a viable source to replace fossil fuels. However, challenges associated with site selection for solar panel installation inhibit the uptake of solar energy systems. Expressway slopes offer a potentially attractive alternative for solar panel installation for the following reasons: expressway slopes are vacant public sites, they are abundant (about 4,193km in South Korea), and they are linear in nature. Traditoinally when selecting sites for solar systems conventional surveying methods are employed. Unfortunately, these methods can be dangerous, time consuming, and labor intensive. To overcome these limitations of conventional site selection methodologies, we propose an automated approach using numerical maps. First, contour and expressway polylines are extracted separately from numeric maps. The extracted contour lines are then converted into a digital terrain model; this is used to calculate aspect and slope information. Next, the extracted expressway lines are projected onto a binary image and refined to recover the disconnections, and then applied to create a buffer zone to narrow the search space. Finally, all data sets are overlaid to identify candidate sites for solar panel systems and are visually verified through comparisons with aerial photos.

Automatic Building Modeling Method Using Planar Analysis of Point Clouds from Unmanned Aerial Vehicles (무인항공기에서 생성된 포인트 클라우드의 평면성 분석을 통한 자동 건물 모델 생성 기법)

  • Kim, Han-gyeol;Hwang, YunHyuk;Rhee, Sooahm
    • Korean Journal of Remote Sensing
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    • v.35 no.6_1
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    • pp.973-985
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    • 2019
  • In this paper, we propose a method to separate the ground and building areas and generate building models automatically through planarity analysis using UAV (Unmanned Aerial Vehicle) based point cloud. In this study, proposed method includes five steps. In the first step, the planes of the point cloud were extracted by analyzing the planarity of the input point cloud. In the second step, the extracted planes were analyzed to find a plane corresponding to the ground surface. Then, the points corresponding to the plane were removed from the point cloud. In the third step, we generate ortho-projected image from the point cloud ground surface removed. In the fourth step, the outline of each object was extracted from the ortho-projected image. Then, the non-building area was removed using the area, area / length ratio. Finally, the building's outer points were constructed using the building's ground height and the building's height. Then, 3D building models were created. In order to verify the proposed method, we used point clouds made using the UAV images. Through experiments, we confirmed that the 3D models of the building were generated automatically.

A Study on the Development and Utilization of Indoor Spatial Information Visualization Tool Using the Open BIM based IFC Model (개방형 BIM 기반 IFC 모델을 이용한 실내공간정보 시각화 도구개발 및 활용방안 연구)

  • Ryu, Jung Rim;Mun, Son Ki;Choo, Seung Yeon
    • Spatial Information Research
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    • v.23 no.5
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    • pp.41-52
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    • 2015
  • MOLIT (Minister of Land, Infrastructure and Transport) authorized Indoor Spatial Information as Basic spatial information in 2013. It became a legal evidence for constructing and managing Indoor Spatial Information. Although it has a little advantage to utilize as service level that Indoor Spatial Information by laser scan or measurement, it has a lot of problems such as consuming many resources, requiring additional progresses for inputting Object Information. In conclusion, it is inefficient to utilize for the maintenance and domestic AEC/FM field. The purposes of this study is to output Indoor Spatial Information by operating IFC model which based on open BIM and to improve availability of Indoor Spatial Information with data visualization. The open-sources of IFC Exporter, a inner program of Revit (Autodesk Inc), is used to output Indoor Spatial Information. Directs 3D Library is also operated to visualize Indoor Spatial Information. It is possible to inter-operate between XML format and the objects of Indoor Spatial Information. It can be utilized in various field as well. For example COBie linkage in facility management, construction of geo-database using air-photogrammetry of UAV (Unmaned Areal Vehicle), the simulation of large-scale military operations and the simulation of large-scale evacuation. The method that is purposed in this study has outstanding advantages such as conformance with national spatial information policy, high level of interoperability as indoor spatial information objects based on IFC, convenience of editing information, light level of data and simplifying progress of producing information.

Analysis of Data Characteristics by UAV LiDAR Sensor (무인항공 LiDAR 센서에 따른 데이터 특성 분석)

  • Park, Joon-Kyu;Lee, Keun-Wang
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.5
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    • pp.1-6
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    • 2020
  • UAV (Unmanned Aerial Vehicles) are used widely for military purposes because they are more economical than general manned aircraft and satellites, and have easy access to the object. Recently, owing to the development of IT technology, UAV equipped with various sensors have been released, and their use is increasing in a wide range of fields, such as surveying, agriculture, meteorological observation, communication, broadcasting, and sports. An increasing number of studies and attempts have made use of it. On the other hand, existing research was related mostly to photogrammetry, but there has been a lack of analytical research on LiDAR (Light Detection And Ranging). Therefore, this study examined the characteristics of a UAV LiDAR sensor for the application of a geospatial information field. In this study, the performance of commercialized LiDAR sensors, such as the acquisition speed and the number of echoes, was investigated, and data acquisition and analysis were conducted by selecting Surveyor Ultra and VX15 models with similar accuracy and data acquisition distances. As a result, a DSM of each study site was generated for each sensor, and the characteristics of data density, precision, and acquisition of ground data from vegetation areas were presented through comparison. In addition, the UAV LiDAR sensor showed an accuracy of 0.03m ~ 0.05m. Hence, it is necessary to select equipment considering the characteristics of data for effective use. In the future, the use of UAV LiDAR may be suggested if additional data can be obtained and analyzed for various areas, such as urban areas and forest areas.

Accuracy Evaluation of 3D Slope Model Produced by Drone Taken Images (드론 촬영으로 작성한 비탈면 3차원 모델의 품질 분석)

  • Kang, Inkyu;Kim, Taesik
    • Journal of the Korean Geoenvironmental Society
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    • v.21 no.6
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    • pp.13-17
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    • 2020
  • In the era of the fourth industrial revolution, drones are being used in various civil engineering fields. Currently, the construction and maintenance of slopes are generally managed by manpower. This method has a risk of safety accidents, and it is difficult to accurately evaluate the slope because it is difficult to secure the vision. In this paper, the effects of RTK and GCP on the 3D model of the slope were studied by using digital images taken by the drone. GNSS coordinates were measured for nine points to compare the quality of the slope 3D model, three points of which were used as the check points and the remaining points were used as GCPs. When making the 3D model of the slope using high-accuracy geotagging images using RTK, it was found that the error at the check point decreases as the number of GCP increases. Even if GNSS was used, it was found that the error at the check points of the 3D slope model was not significant when the GCPs were applied. However, it was found that even if high-accuracy geotagging images are used using the RTK module, a significant error occur when the 3D slope model is created without applying GCPs. Therefore, it can be stated that GCP must be applied to create the 3D slope model in which information about the height as well as plane information is important.

The Study to Improve Re-topology Efficiency Between Analyzing Software and Making Examples of Different Types of 3D Models (리토폴로지 효율성 향상을 위한 소프트웨어의 비교분석 및 유형별 3D 모델링 사례 제작)

  • Yan, Yong
    • The Journal of the Korea Contents Association
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    • v.20 no.6
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    • pp.9-25
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    • 2020
  • As laser scan and photogrammetry are extensively applied to 3D modeling, the Retopology has become a critically important part in the 3D modeling process. However, abundant time would be wasted if the wrong method for retopology is employed. This paper aims to select the most suitable method and software for retopology for different types of models so as to increase the effectiveness of 3D modeling. In this paper, retopology is divided into three types according to the existed software for retopology in the market: manual, automatic and wrapping type, all of which are investigated by their characteristics of retopology and software in which they are applied individually. Then case production is employed on Static Mesh Skeletal Mesh and Hard Surface Modeling by the above mentioned three methods. The advantages and disadvantages of the software in which the above three methods can be applied are summed up, and the manual type produces good results, the automatic type is fast, and the wrapping type requires a pre-existing base mesh and the most suitable method for retopology for each type of 3D models is demonstrated. This paper provides reference for retopology and increases the effectiveness of 3D modeling.