최대 가중 클릭 문제의 동적 생성법을 이용한 온라인 다중 카메라 다중 물체 추적 기법

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 8. 최진영.In this dissertation, we propose an online and real-time algorithm for tracking of multiple targets with multiple cameras that have overlapping field of views. Because of its applicability, multiple target tracking with a visual sensor has been studied intensively during the recent decades. Especially, algorithms using multiple overlapping cameras have been proposed to overcome the occlusion and missing problem of target that cannot be resolved by a single camera. Since the multiple camera multiple target tracking (MCMTT) problem is more complicated than the single camera multiple target tracking (SCMTT) problem, most of MCMTT algorithms are based on a batch process which considers a whole sequence at a time. Although the batch-based algorithms have been achieved the robust performance, their usability is limited because many practical applications need an instantaneous result. The objective of this dissertation is to develop an online MCMTT algorithm that has compatible tracking performance compared to the batch-based algorithms, but requires a small amount of computations. The proposed algorithm generates track hypotheses (or simply called `track') with all possible data associations between object detections from multiple cameras through frames. Then, it picks a set of tracks that best describes the tracking of targets. To identify a good track, the quality of each track is measured by our score function. The tracking solution is, then, a set of tracks that has the maximum total score. To get the solution, we formulate the problem of finding those track set as the maximum weighted clique problem (MWCP), which is one of the widely adopted formulations for a combinatorial problem that has the pairwise compatibility relationship among the variables. MWCP is well-known NP-complete problem and its worst-case computation time is proportional to the exponent of the number of tracks. Thus, solving MWCP is intractable because the number of candidate tracks exponentially increases when the tracking progresses. To alleviate the huge computational load, we propose an online scheme that dynamically formates multiple MWCPs with small-sized subsets of candidate tracks in every frame. The scheme is motivated by that the tracking solutions from consecutive frames are very similar because the status of each target is not abruptly changed between one frame. When we assume that a specific track set is an actual solution of the previous frame, only a small number of tracks have a possibility to become a solution track of the current frame. Thus, we can narrow down the size of candidate track set with the previous solution. However, propagating only the best solution of each frame can cause irreducible error when a wrong track set is chosen as the solution because of the tracking ambiguity. To hedge the risk of this error, we find multiple good solutions at each frame and propagate the K-best solutions among them to the next frame instead of a single solution. When the candidate tracks are updated and generated with newly obtained detections at the next frame, we generate multiple subsets of the entire candidate tracks with the K-best previous solutions. Each subset consists of candidate solution tracks with respect to each of the previous solutions, and a small-sized MWCP is formated with the subset. Then, our algorithm finds multiple solutions from each MWCP and repeats above procedures until the tracking is terminated. Even the proposed algorithm solves multiple MWCPs, it has lower computational complexity than solving a single MWCP with the entire candidate tracks because the overall computational load is mainly affected by the size of the largest MWCP. Moreover, when an instantaneous result is demanded, our algorithm finds better solution than solving a single large-sized MWCP because it finds more diverse solutions under a limited solving time. Although our dynamic formulation remarkably moderates the overall computational complexity, it is still challenging to satisfy the real-time capability of the tracking system. Thus, we apply three more strategies to reduce the computation time. First, we generate tracklets, robust fragments of a target's trajectory, at each camera and generate candidate tracks with those tracklets instead of detections. This prevents a generation of many absurd tracks. Second, we adopt a heuristic algorithm called a breakout local search (BLS) to solve each MWCP. With BLS, multiple suboptimal solutions can be found efficiently within a short time. Last, we prune the candidate tracks with a probability that is calculated with the K-best solutions. The probability represents the quality of each track with respect to the overall tracking situation instead of an individual track. Thus, utilizing this probability ensures a proper pruning of candidate tracks. In the experiments with a public benchmark dataset, our algorithm shows the compatible performance compared to the state-of-the-art batch-based MCMTT algorithms. Moreover, our algorithm shows a real-time capability by achieving a satisfactory performance within a reasonable computation time. We also conduct a self-comparison to verify our dynamic MWCP formation with respect to the tracking performance and solving time. When a sufficient number of solutions are propagated, our algorithm performs better and takes shorter time than solving a single MWCP considering the entire candidate tracks.Chapter 1 Introduction 1 1.1 Background 1 1.2 Related Works 3 1.2.1 Reconstruction-and-tracking methods 4 1.2.2 Tracking-and-reconstruction methods 6 1.2.3 Unified frameworks 7 1.3 Contents of the Research 8 1.4 Thesis Organization 11 Chapter 2 Preliminaries 13 2.1 Bayesian Tracking 14 2.1.1 Recursive Bayesian Tracking 16 2.1.2 Bayesian Tracking for Multiple Targets 17 2.1.3 Multiple Hypothesis Tracking (MHT) 19 2.2 Maximum Weighted Clique Problem (MWCP) 24 2.2.1 Clique Problems 24 2.2.2 Solving MWCP 26 2.3 Breakout Local Search (BLS) 27 2.3.1 Solution exploration 28 2.3.2 Perturbation Strategies 30 2.3.3 Initial Solution and Termination Condition 32 Chapter 3 Proposed Approach 35 3.1 Problem Statements 35 3.2 Tracklet Generation 40 3.2.1 Detection-to-tracklet Matching 43 3.2.2 Matching Score with Motion Estimation 46 3.2.3 Matching Validation 49 3.3 Track Hypothesis 51 3.3.1 Tracklet Association 51 3.3.2 Online Generation of Association Sets 55 3.3.3 Track Generation 57 3.3.4 Track Score 59 3.4 Global Hypothesis 64 3.4.1 MWCP for MCMTT 65 3.4.2 BLS for MCMTT 69 3.5 Pruning 70 3.5.1 Approximated Global Track Probability 71 3.5.2 Track Pruning Scheme 72 Chapter 4 Experiments 75 4.1 Comparison with the State-of-the-art Methods 81 4.2 Influence of Parameters 84 4.3 Score Function Analysis 87 4.4 Solving Scheme Analysis 88 4.5 Qualitative Results 90 Chapter 5 Concluding Remarks 97 5.1 Conclusions 97 5.2 Future Works 98 초록 117Docto

CRTC3 depletion prevents melanocyte differentiation in epidermis and hair follicle

The mechanisms that lead to variation in human skin and hair color are not fully understood and melanocyte system is the most important strategy against environmental hazards. To better understand the molecular control of skin and hair color variation and tanning response (as a tool of environmental prevention response) to cAMP stimuli (UVR), we knocked out modulation of the expression of CRTC3 (CREB-regulated transcriptional co-activator 3), CREB coactivator in mice. Depletion of CRTC3 was sufficient to lighten the color of the mouse hair and tail (ear) skin in Knock-out (K/O). Ultra-structural studies revealed that depletion of CRTC3 inhibited the accumulation of both early and mature melanosomes while melanin contents and early and late melanogenesis-associated genes were much reduced in hairy dorsal skin and tail skin. Knock-down (K/D) of CRTC3 in mel-ab cells and primary cultured cells from the mice showed consistent results with those of in vivo and cAMP tended to recover the downregulation of melanogenesis genes. These results indicated that CRTC3 is a determinant of color of skin and hair both ways of facultative (basal) and stimulated state of adapted melanogenesis. CRTC3 contributes to melanogenesis by modulating CRTC3/MITF.Docto

METHOD FOR GENERATING TRIANGLE MESHES OF TWO-DIMENSIONAL DATA USING WAVELET COEFFICIENTS

본 발명은 컴퓨터 그래픽에 있어서 2차원 데이터의 3차원 시각화를 위한 메쉬 모델링에 관한 것으로서, 특히 2차원 데이터를 웨이블릿 변환하여 얻어진 웨이블릿 계수를 직접 이용한 2차원 데이터의 삼각형 메쉬 근사 방법에 관한 것으로, 2차원 정규 격자 데이터를 입력으로 하여 2단계 웨이블릿 변환을 수행한 다음, 주어진 문턱 값 보다 큰 웨이블릿 변환 계수(중요 웨이블릿 변환 계수)의 위치를 검출하고, 중요 웨이블릿 변환 계수의 위치에 따라 사각형 격자 나누기를 수행하여 4진 트리를 생성한 후, 생성된 4진 트리를 삼각형 메쉬로 바꾸어 준다.본 발명은 웨이블릿 변환 계수로 직접 데이터 영역의 복잡도를 판단하여 격자를 나누고 이를 삼각형 메쉬로 바꾸어 주므로, 웨이블릿 변환된 데이터를 저장하여 이용하면 별도의 복잡도 계산 없이 고속으로 삼각형 메쉬를 생성할 수 있으며, 기존의 영상처리분야의 영상 압축 기법과 손쉽게 접목이 가능하여 아주 큰 용량의 데이터도 효과적으로 관리할 수 있도록 해준다

데이터 압축 및 메쉬 근사 기법을 이용한 대용량 지형 정보 데이터를 위한 3차원 랜더링 시스템에 관한 연구

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 1999.8, [ x, 75 p. ]In this dissertation, we present a new mesh approximation method for the regular gird 2-D data in order to implement a fly-through simulator. The proposed mesh approximation method uses wavelet coefficients as the local area complexity measures. To utilize the characteristics of wavelet transform (WT), we examine the characteristics of WT and devise a new mesh approximation scheme. Since the wavelet transform has the spatio-frequency localization characteristic, this method only selects the wavelet coefficients larger than a given threshold and constructs quadtree based triangular meshes using them. Computer simulation results show the advantages of the proposed method in PSNR and visual quality. As the size of terrain data becomes larger, the need for the effective terrain data management scheme is increased. Hence, in this dissertation, we also propose and implement a new 3-D rendering system to visualize the very large terrain data. It combines an image compression method and the visualization scheme mentioned above. For the efficient data compression, the set partitioning in hierarchical tree (SPIHT) codec, which is a kind of progressive codec based on wavelet transform and the block-based data compression method are adopted. The rendering system decodes the compressed terrain data block by block depending on the visual resolution based on the local level of detail method and makes a triangular mesh based on the proposed mesh approximation method. Since the compression of terrain data and level of detail in mesh approximation are combined algorithm, the rendering system can manage the large terrain data effectively. Computer simulation shows that the proposed rendering system can provide good visual quality as well as high performance. The proposed system can be applicable to various fields, such as, flight simulator and computer games한국과학기술원 : 전기및전자공학과

Development of the graphic editor and script tool for multimedia

학위논문(석사) - 한국과학기술원 : 전기 및 전자공학과, 1993.2, [ [ii], 76 p. ]한국과학기술원 : 전기 및 전자공학과

Ursodeoxycholic Acid May Inhibit Environmental Aging-Associated Hyperpigmentation

Extrinsic aging of the skin caused by ultraviolet (UV) light or particulate matter is often manifested by hyperpigmentation due to increased melanogenesis in senescent skin. Ursodeoxycholic acid (UDCA), which has been commonly used as a health remedy for liver diseases, is known to possess antioxidant properties. This study was done to investigate whether UDCA inhibits cellular aging processes in the cells constituting human skin and it reduces melanin synthesis. ROS, intracellular signals, IL-1 alpha, IL-8, TNF-alpha, cyclooxygenase (COX)-2, type I collagen, and matrix metalloproteinases (MMPs) levels were measured in human dermal fibroblasts treated with or without UDCA after UV exposure. Melanin levels and mechanistic pathways for melanogenesis were investigated. UDCA decreased ROS, senescence-associated secretory phenotype (SASP), and proinflammatory cytokines induced by UV treatment. UDCA reduced melanogenesis in normal human melanocytes cocultured with skin constituent cells. Our results suggest that UDCA could be a comprehensive agent for the treatment of environmental aging-associated hyperpigmentation disorders