홍성 신경리 마애여래입상의 3차원 기록화를 통한 포토그래메트리의 유용성 연구

오준영,김충식 국립문화재연구원 2017 헤리티지:역사와 과학 Vol.50 No.3

The purpose of this study is to improve the usefulness of photogrammetry in the field of cultural heritage recording concentrated on laser scanning. Two measurement methods(laser scanning, photogrammetry) were compared in terms of accuracy and reality for the Rock-carved Standing Buddha in Singyeong-ri, Hongseong. With regard to accuracy, the distances of major points by both shape information and between the two shape information were compared. Only a deviation of about 1mm was found in the distance measurement of the major points by both shape information. In particular, the average distance between two shape information identified through aligning was only about 0.01mm. Also, the absolute deviation within about 2mm accounted for 70% of the total, and the absolute deviation within about 3.5mm was found to be 95.4% of the total. These values showed very high similarity between laser scanning and photogrammetry based shape information. In respect of reality, the carved depth, texture, and patterns were compared. As a result of comparing four cross-sectional shapes, only slight differences were found in the shape information of both measurement techniques and similar shapes were identified. The overall texture of both shape information was also similar. However, the detailed shape based on the photogrammetry with decimation is realized with a smoother texture than the original and laser scanning. In particular, Photogrammetry also realistically expressed the various ornaments carved in the Rock-carved Buddha and the patterns with shallow depths were comparatively detailed. 이 연구는 레이저스캐닝 중심의 문화유산 기록화 분야에서 포토그래메트리의 유용성 제고에 목적을 두고 있다. 두 계측기술(레이저스캐닝, 포토그래메트리)은 홍성 신경리 마애여래입상을 중심으로 정확성과 사실성 측면에서 비교되었다. 정확성 측면에서는 형상정보별 주요 지점과 두 형상정보 사이의 거리가 비교되었다. 마애불의 형상정보별 주요 지점의 거리 측정에서는 약 1mm 내외의 편차만이 확인되었다. 특히 정합을 통해 확인된 두 형상정보 사이의 평균거리는 약 0.01mm에 불과했다. 또한 약 2mm 이내의 절대편차가 전체의 70%를 차지하였으며, 약 3.5mm 이내의 절대편차가 전체의 95.4%로 확인되었다. 이러한 수치들은 레이저스캐닝 대비 포토그래메트리의 매우 높은 일치도를 보여주었다. 사실성 측면에서는 조각 깊이, 질감, 문양이 비교되었다. 4개의 단면 형상을 비교한 결과 두 계측기술별 형상정보는 미세한 차이만을 보였고, 전반적으로 유사한 형상이 확인되었다. 두 형상정보의 전체적인 질감도 유사하였다. 하지만 데시메이션이 적용된 포토그래메트리 기반의 세부 형상은 실물과 레이저스캐닝에 비해 매끄러운 질감으로 구현되었다. 특히 포토그래메트리는 레이저스캐닝과 동일하게 마애불에 조각된 다양한 문양도 사실적으로 구현하였으며, 얕은 깊이의 문양도 비교적 세밀하게 나타났다.

Thermographic analysis of the effect of composite type, layering method, and curing light on the temperature rise of photo-cured composites in tooth cavities

Kim, M.J.,Kim, R.J.Y.,Ferracane, J.,Lee, I.B. Munksgaard ; Elsevier Science Ltd 2017 Dental materials Vol.33 No.10

Objectives: The purpose of this study was to investigate temperature rise in the composite and dentin of a class I cavity in extracted human molars under different restoration conditions, including the use of different composite types, layering methods, and curing lights. Methods: Open occlusal cavities were prepared on 28 extracted human molars. A conventional (Filtek Z250) and a bulk-fill (Filtek Bulk Fill Posterior; BFP) composite were used to restore the preparations. BFP was incrementally layered or bulk-filled. Bulk-filled BFP was cured with two different lights, the Elipar S10 and the BeLite. Each layer was illuminated for 20s, while thermograms of the specimens were recorded for 100s using an infrared thermal camera. Temperature changes on the composite and dentin surfaces were obtained at points of interest (POI) pertaining to successive incremental distances of 0.75mm from the top of the cavity to the pulp. The polymerization kinetics of each composite was determined using photo-differential scanning calorimetry. Results: The greatest temperature rise was observed 0.75mm apical from the top of the cavity. All groups showed over 6<SUP>o</SUP>C maximum temperature rise (ΔT<SUB>max</SUB>) at the pulpal side of the dentin. Upon curing, Z250 reached ΔT=5<SUP>o</SUP>C faster than BFP; however, ΔT<SUB>max</SUB> of the two composites were comparable at any POI. Bulk filling showed greater ΔT<SUB>max</SUB> than incremental filling at 0.75mm apical from the top and in the middle of the cavity. The Elipar S10 light generated faster temperature changes in the curing composite at all recorded positions throughout the depth of the cavity and greater ΔT<SUB>max</SUB> in all POIs compared to BeLite. Significance: Real-time thermographic analysis demonstrated that the composite type and layering method did not influence the temperature rise at the pulpal side of dentin during composite restoration of an occlusal preparation in a tooth. The amount and initial rate of temperature increase was most affected by the radiant exposure of the light curing unit. Within the limitations of this in vitro study, when irradiation time is constant, a curing light with higher radiant power can induce relatively high thermal transfer, thereby increasing the risk of pulpal damage.

Comparison of Yittria Stabilized Zirconia Electrolytes(YSZ) for Thin Film Solid Oxide Fuel Cell by Atomic Layer Deposition and Sputtering

탄비르 와카스하산(Tanveer, Waqas Hassan),하승범(Ha, Seung Bum),지상훈(Ji, Sanghoon),차석원(Cha, Suk Won) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11

In this research, two thin film deposition techniques, Atomic Layer Deposition and Sputtering are carried out for the fabrication of Yittria Stabilized Zirconia electrolyte for thin film Solid Oxide Fuel Cell. Zirconium to Yittrium ratio for both cases is about 1/8. Scanning Electron Microscope(SEM) image shows that the growth rate per hour for Atomic Layer Deposition is faster than for sputtering. X-ray Photo-electron Spectroscopy(XPS) shows that the peaks of both Zirconia and Yittria shift towards higher bending energy for the case of Atomic Layer deposition and thus are more strongly attached to the substrate. Later, Nyquist plot was used to compare the conductivity of Yittria Stabilized Electrolyte for both cases. The conductivity at 300?C for Atomic Layer Deposited Yittria Stabilized Zirconia is found to be 5{times}10^{-4}S/cm while that for sputtered Yittria Stabilized Zirconia is 2{times}10^{-5}S/cm at the same temperature. The reason for better performance for Atomic Layered YSZ is believed to be the Nano-structured layer fabrication that aids in along the plane conduction as compared to the columnarly structured Sputtered YSZ.

A New True Ortho-photo Generation Algorithm for High Resolution Satellite Imagery

방기인,김창재 대한원격탐사학회 2010 大韓遠隔探査學會誌 Vol.26 No.3

Ortho-photos provide valuable spatial and spectral information for various Geographic Information System (GIS) and mapping applications. The absence of relief displacement and the uniform scale in ortho-photos enable interested users to measure distances, compute areas, derive geographic locations, and quantify changes. Differential rectification has traditionally been used for ortho-photo generation. However, differential rectification produces serious problems (in the form of ghost images) when dealing with large scale imagery over urban areas. To avoid these artifacts, true ortho-photo generation techniques have been devised to remove ghost images through visibility analysis and occlusion detection. So far, the Z-buffer method has been one of the most popular methods for true ortho-photo generation. However, it is quite sensitive to the relationship between the cell size of the Digital Surface Model (DSM) and the Ground Sampling Distance (GSD) of the imaging sensor. Another critical issue of true ortho-photo generation using high resolution satellite imagery is the scan line search. In other words, the perspective center corresponding to each ground point should be identified since we are dealing with a line camera. This paper introduces alternative methodology for true ortho-photo generation that circumvents the drawbacks of the Z-buffer technique and the existing scan line search methods. The experiments using real data are carried out while comparing the performance of the proposed and the existing methods through qualitative and quantitative evaluations and computational efficiency. The experimental analysis proved that the proposed method provided the best success ratio of the occlusion detection and had reasonable processing time compared to all other true ortho-photo generation methods tested in this paper.

A New True Ortho-photo Generation Algorithm for High Resolution Satellite Imagery

( Ki In Bang ),( Chang Jae Kim ) 대한원격탐사학회 2010 大韓遠隔探査學會誌 Vol.26 No.3

Ortho-photos provide valuable spatial and spectral information for various Geographic Information System (GIS) and mapping applications. The absence of relief displacement and the uniform scale in ortho-photos enable interested users to measure distances, compute areas, derive geographic locations, and quantify changes. Differential rectification has traditionally been used for ortho-photo generation. However, differential rectification produces serious problems (in the form of ghost images) when dealing with large scale imagery over urban areas. To avoid these artifacts, true ortho-photo generation techniques have been devised to remove ghost images through visibility analysis and occlusion detection. So far, the Z-buffer method has been one of the most popular methods for true ortho-photo generation. However, it is quite sensitive to the relationship between the cell size of the Digital Surface Model (DSM) and the Ground Sampling Distance (GSD) of the imaging sensor. Another critical issue of true ortho-photo generation using high resolution satellite imagery is the scan line search. In other words, the perspective center corresponding to each ground point should be identified since we are dealing with a line camera. This paper introduces alternative methodology for true ortho-photo generation that circumvents the drawbacks of the Z-buffer technique and the existing scan line search methods. The experiments using real data are carried out while comparing the performance of the proposed and the existing methods through ualitative and quantitative evaluations and computational efficiency. The experimental analysis proved that the proposed method provided the best success ratio of the occlusion detection and had reasonable processing time compared to all other true ortho-photo generation methods tested in this paper.

A New True Ortho-photo Generation Algorithm for High Resolution Satellite Imagery

Bang, Ki-In,Kim, Chang-Jae The Korean Society of Remote Sensing 2010 大韓遠隔探査學會誌 Vol.26 No.3

Ortho-photos provide valuable spatial and spectral information for various Geographic Information System (GIS) and mapping applications. The absence of relief displacement and the uniform scale in ortho-photos enable interested users to measure distances, compute areas, derive geographic locations, and quantify changes. Differential rectification has traditionally been used for ortho-photo generation. However, differential rectification produces serious problems (in the form of ghost images) when dealing with large scale imagery over urban areas. To avoid these artifacts, true ortho-photo generation techniques have been devised to remove ghost images through visibility analysis and occlusion detection. So far, the Z-buffer method has been one of the most popular methods for true ortho-photo generation. However, it is quite sensitive to the relationship between the cell size of the Digital Surface Model (DSM) and the Ground Sampling Distance (GSD) of the imaging sensor. Another critical issue of true ortho-photo generation using high resolution satellite imagery is the scan line search. In other words, the perspective center corresponding to each ground point should be identified since we are dealing with a line camera. This paper introduces alternative methodology for true ortho-photo generation that circumvents the drawbacks of the Z-buffer technique and the existing scan line search methods. The experiments using real data are carried out while comparing the performance of the proposed and the existing methods through qualitative and quantitative evaluations and computational efficiency. The experimental analysis proved that the proposed method provided the best success ratio of the occlusion detection and had reasonable processing time compared to all other true ortho-photo generation methods tested in this paper.

A Study of Utilizing 2D Photo Scan Technology to Efficiently Design 3D Models

곽대위,정진헌 한국디지털정책학회 2017 디지털융복합연구 Vol.15 No.7

Generally, in special effect video and 3D animation design process, character and background’s 3D model is built by 3D program like MAYA or 3DS MAX. But in that manual modeling mode, model design needs much time and costs much money. In this paper, two experimental groups are set to prove use 2D photo scan modeling mode to build 3D model is effective and advanced. The first experimental group is modeling the same object by different experimental setting. The second experimental group is modeling the same background by different experimental setting. Through those two experimental groups, we try to find an effective design method and matters need attention when we use photo scan design mode. We aim to get the model from whole experiment and prove photo scan modeling mode is effective and advanced.

A Study of Utilizing 2D Photo Scan Technology to Efficiently Design 3D Models

Dawei Guo,Jeanhun Chung 한국디지털정책학회 2017 디지털융복합연구 Vol.15 No.7

촬영 각도에 따른 3D 모델 복원 품질 비교 연구 : 포토그래메트리를 중심으로

임재현,이승빈,소요환 한국디지털콘텐츠학회 2023 한국디지털콘텐츠학회논문지 Vol.24 No.1

3D scanning photogrammetry technology based on image analysis has a history as long as that of photography for about 150 years. Graphic processors and cameras have also achieved dramatic performance developments in the same way as the long history and progressing. However, non-standardized imaging processes are accompanied by problems such as structural defects in the reconstructed object and the generation of noise. In this research, first, we will model and 3D print the terracotta army object used in the actual measurement data (Ground Truth). Second, in order to derive the optimal shooting method, we developed a table 3D scanning system that rotates around a total of two axes, the vertical axis and the horizontal axis and Get photo data. Finally, the acquired data are compared and analyzed for quality and similarity using a C2M (Cloud-to-Mesh Distances) quantitative comparison algorithm. 높은 비용과 기술적 전입 장벽으로 인해 건축 또는 토목 분야에서 측량을 위해 한정적으로 사용되어온 이미지 분석 기반 3D 스캔 방식 포토그래메트리(Photogrammetry) 기술은 약 150년의 사진 만큼이나 오랜 역사를 가지고 있다. 긴 역사만큼 그래픽 프로세서와 카메라 또한 비약적인 성능 발전을 이루었는데, 포토그래메트리 기술은 이와 함께 건축, 토목뿐만이 아닌 다양한 분야에 활용되고 있고 실제로 다수의 포토그래메트리 기술 기반 3D 모델 복원 과정에 대한 연구가 진행되고 있다. 하지만 표준화되지 않은 촬영 프로세스로 인해 복원 물체의 구조적 결함이나 노이즈(Noise)의 발생과 같은 문제점이 수반된다. 본 연구에서는 첫째, 실측 자료(Ground Truth)로 쓰일 병마용(兵馬俑) 오브젝트를 모델링하고 3D 프린팅한다. 둘째, 최적의 촬영 방법을 도출하기 위해 세로축과 가로축, 총 두 축을 중심으로 회전하는 테이블 3D 스캐닝 시스템을 개발하고, 해당 시스템에서 스마트폰 카메라를 통해 다각도에서 대상 물체의 사진 데이터를 획득한다. 마지막으로는 획득한 데이터를 C2M(Cloud-to-Mesh Distances) 정량적 비교 알고리즘을 사용하여 품질과 유사도를 비교‧분석한다.

A Zero-Watermark Scheme for Identification Photos based on QR Code and Visual Cryptography

De Li,Zhe Liu,LiHua Cui 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.1

This paper proposes a zero-watermark scheme for identification photos based on QR code and visual cryptography. The method makes no changes to original images while embedding the QR code watermark. In order to ensure the security, we use Arnold transformation to scrambling the watermark. In the scheme, we use discrete wavelet transform and matrix norm computing to generate the invariant feature values against print-scan attacks. Then the VC scheme is applied to generate the secret image from the feature values and the disturbed watermark by using a codebook. In the extraction scheme, we get the secret image which is registered to certification authority and the feature values extracted from the examined image with VC scheme, and then apply inverse Arnold transformation to restore the watermark, finally repair position patterns of the QR code. The experimental results show that the proposed algorithm is effective and robust against attacks such as JPEG compression, add noise, multiple filters, scale, little angle rotation and crop, especial print-scan attacks.