scholarly journals DFTHR: A Distributed Framework for Trajectory Similarity Query Based on HBase and Redis

Information ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 77 ◽  
Author(s):  
Jiwei Qin ◽  
Liangli Ma ◽  
Qing Liu
Keyword(s):  
Navigation Systems ◽  
Trajectory Data ◽  
Distributed Framework ◽  
Parallel Query ◽  
Similarity Query ◽  
Trajectory Similarity ◽  
Query Algorithm ◽  
The Cost ◽  
Huge Challenge ◽  
Centralized System

In recent years positioning sensors have become ubiquitous, and there has been tremendous growth in the amount of trajectory data. It is a huge challenge to efficiently store and query massive trajectory data. Among the typical operation over trajectories, similarity query is an important yet complicated operator. It is useful in navigation systems, transportation optimizations, and so on. However, most existing studies have focused on handling the problem on a centralized system, while with a single machine it is difficult to satisfy the storage and processing requirements of mass data. A distributed framework for the similarity query of massive trajectory data is urgently needed. In this research, we propose DFTHR (distributed framework based on HBase and Redis) to support the similarity query using Hausdorff distance. DFTHR utilizes a segment-based data model with a number of optimizations for storing, indexing and pruning to ensure efficient querying capability. Furthermore, it adopts a bulk-based method to alleviate the cost for adjusting partitions, so that the incremental dataset can be efficiently supported. Additionally, DFTHR introduces a co-location-based distributed strategy and a node-locality-based parallel query algorithm to reduce the inter-worker cost overhead. Experiments show that DFTHR significantly outperforms other schemes.

scholarly journals Evaluating the effect of compressing algorithms for trajectory similarity and classification problems

2021 ◽  
Author(s):  
Antonios Makris ◽  
Camila Leite da Silva ◽  
Vania Bogorny ◽  
Luis Otavio Alvares ◽  
Jose Antonio Macedo ◽  
...  
Keyword(s):  
Trajectory Analysis ◽  
Similarity Measures ◽  
Classification Problems ◽  
Trajectory Data ◽  
Compression Algorithms ◽  
Time Ratio ◽  
Ratio Speed ◽  
Trajectory Similarity ◽  
Real World Datasets ◽  
The Impact

AbstractDuring the last few years the volumes of the data that synthesize trajectories have expanded to unparalleled quantities. This growth is challenging traditional trajectory analysis approaches and solutions are sought in other domains. In this work, we focus on data compression techniques with the intention to minimize the size of trajectory data, while, at the same time, minimizing the impact on the trajectory analysis methods. To this extent, we evaluate five lossy compression algorithms: Douglas-Peucker (DP), Time Ratio (TR), Speed Based (SP), Time Ratio Speed Based (TR_SP) and Speed Based Time Ratio (SP_TR). The comparison is performed using four distinct real world datasets against six different dynamically assigned thresholds. The effectiveness of the compression is evaluated using classification techniques and similarity measures. The results showed that there is a trade-off between the compression rate and the achieved quality. The is no “best algorithm” for every case and the choice of the proper compression algorithm is an application-dependent process.

scholarly journals Trajectory Similarity Analysis with the Weight of Direction and k-Neighborhood for AIS Data

2021 ◽  
Vol 10 (11) ◽  
pp. 757
Author(s):  
Pin Nie ◽  
Zhenjie Chen ◽  
Nan Xia ◽  
Qiuhao Huang ◽  
Feixue Li
Keyword(s):  
Traffic Management ◽  
Similarity Analysis ◽  
Automatic Identification ◽  
Identification System ◽  
Trajectory Data ◽  
Motion Direction ◽  
Maritime Traffic ◽  
A Cell ◽  
Robustness To Noise ◽  
Trajectory Similarity

Automatic Identification System (AIS) data have been widely used in many fields, such as collision detection, navigation, and maritime traffic management. Similarity analysis is an important process for most AIS trajectory analysis topics. However, most traditional AIS trajectory similarity analysis methods calculate the distance between trajectory points, which requires complex and time-consuming calculations, often leading to substantial errors when processing AIS trajectory data characterized by substantial differences in length or uneven trajectory points. Therefore, we propose a cell-based similarity analysis method that combines the weight of the direction and k-neighborhood (WDN-SIM). This method quantifies the similarity between trajectories based on the degree of proximity and differences in motion direction. In terms of its effectiveness and efficiency, WDN-SIM outperformed seven traditional methods for trajectory similarity analysis. Particularly, WDN-SIM has a high robustness to noise and can distinguish the similarities between trajectories under complex situations, such as when there are opposing directions of motion, large differences in length, and uneven point distributions.

scholarly journals An Approach to Spatiotemporal Trajectory Clustering Based on Community Detection

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xin Wang ◽  
Xinzheng Niu ◽  
Jiahui Zhu ◽  
Zuoyan Liu
Keyword(s):  
Community Detection ◽  
Trajectory Analysis ◽  
Moving Objects ◽  
Clustering Algorithms ◽  
Similarity Measures ◽  
Detection Algorithm ◽  
Similarity Matrix ◽  
Trajectory Data ◽  
Trajectory Similarity ◽  
Community Detection Algorithm

Nowadays, large volumes of multimodal data have been collected for analysis. An important type of data is trajectory data, which contains both time and space information. Trajectory analysis and clustering are essential to learn the pattern of moving objects. Computing trajectory similarity is a key aspect of trajectory analysis, but it is very time consuming. To address this issue, this paper presents an improved branch and bound strategy based on time slice segmentation, which reduces the time to obtain the similarity matrix by decreasing the number of distance calculations required to compute similarity. Then, the similarity matrix is transformed into a trajectory graph and a community detection algorithm is applied on it for clustering. Extensive experiments were done to compare the proposed algorithms with existing similarity measures and clustering algorithms. Results show that the proposed method can effectively mine the trajectory cluster information from the spatiotemporal trajectories.

scholarly journals The Significance of Computer Modeling and 3D Printing Technology for Facial Ectoprosthetics

2020 ◽  
pp. paper62-1-paper62-10
Author(s):  
Svetlana Cherebylo ◽  
Vyacheslav Vnuk ◽  
Evgeniy Ippolitov ◽  
Mikhail Novikov ◽  
Pavel Mitroshenkov ◽  
...  
Keyword(s):  
3D Printing ◽  
Computer Modeling ◽  
Information Technologies ◽  
Surgical Intervention ◽  
Computer Navigation ◽  
Navigation Systems ◽  
Facial Plastic ◽  
Laser Stereolithography ◽  
Huge Challenge

The integration of information technologies in healthcare practice significantly changes the methods of diagnosis and treatment, the forms of interaction of doctors with patients and colleagues, the organization of treatment and recovery of health. The field of reconstruction of the auricle is still a huge challenge for facial plastic surgeons and requires at various techniques to find the best treatment for each patient. The paper describes the application of computer modeling and laser stereolithography technology in surgical practice for auricular surfaces ectoprosthetics. To improve the accuracy and quality of the surgical intervention the positioning of external prosthesis is applied with the aid of personal templates and computer navigation. The accuracy of ectoprosthesis positioning when using a plastic mask template was 0.3-0.4 mm, while computer navigation was 0.1 - 0.2 mm. Using personalized templates is a simpler and more intuitive way of positioning that does not require expensive computer navigation systems. This example of ectoprosthetics shows the possibilities of various reconstructions of facial organs, not only the ear, but also, for example, the nose, using computer modeling and 3d printing technologies

scholarly journals UTSM: A Trajectory Similarity Measure Considering Uncertainty Based on an Amended Ellipse Model

2019 ◽  
Vol 8 (11) ◽  
pp. 518 ◽  
Author(s):  
Ning Guo ◽  
Shashi Shekhar ◽  
Wei Xiong ◽  
Luo Chen ◽  
Ning Jing
Keyword(s):  
Similarity Measure ◽  
Pattern Mining ◽  
Clustering Methods ◽  
Trajectory Data ◽  
Real World Data ◽  
Asynchronous Sampling ◽  
Ellipse Model ◽  
Spatiotemporal Clustering ◽  
Motion Features ◽  
Trajectory Similarity

Measuring the similarity between a pair of trajectories is the basis of many spatiotemporal clustering methods and has wide applications in trajectory pattern mining. However, most measures of trajectory similarity in the literature are based on precise models that ignore the inherent uncertainty in trajectory data recorded by sensors. Traditional computing or mining approaches that assume the preciseness and exactness of trajectories therefore risk underperforming or returning incorrect results. To address the problem, we propose an amended ellipse model which takes both interpolation error and positioning error into account by making use of motion features of trajectory to compute the ellipse’s shape parameters. A specialized similarity measure method considering uncertainty called UTSM based on the model is also proposed. We validate the approach experimentally on both synthetic and real-world data and show that UTSM is not only more robust to noise and outliers but also more tolerant of different sample frequencies and asynchronous sampling of trajectories.

Effects and Benefits of Space Exploration

2012 ◽  
Vol 2 (1) ◽  
pp. 49-62
Author(s):  
Norma B. Crosby
Keyword(s):  
Space Exploration ◽  
Cost Benefit ◽  
Harsh Environments ◽  
Navigation Systems ◽  
Space Technology ◽  
The Moon ◽  
Modern Life ◽  
Human Needs ◽  
Transfer Of Technology ◽  
The Cost

It has been more than half a century since humans first ventured into space. While competing in being the first to land on the Moon, they learned to utilize space for human needs on Earth (e.g., telecommunications, navigation systems). Many space technologies were later applied to basic needs on Earth. Space research and development led to the “transfer of technology” in non-space sectors and became better known as “spin-offs.” They have improved global modern life in many ways. This paper discusses the cost-benefit of space technology spin-offs, as well as the relationships between various space agencies, spin-offs, and commercial enterprises. Other benefits that have come out of space exploration such as psychological, political and environmental effects are also reviewed, as well as the potential future benefits of going to space. Technologies developed for harsh environments on Earth and for those in space benefit all and collaborating both ways is the future.

The Application of Inertia Navigation Systems to Civil Air Transport

1963 ◽  
Vol 16 (3) ◽  
pp. 265-266
Keyword(s):  
Inertial Sensors ◽  
Instantaneous Velocity ◽  
Air Transport ◽  
Lower Grade ◽  
Navigation Systems ◽  
Military Aircraft ◽  
Considerable Advantage ◽  
Civil Aircraft ◽  
Navigational Aid ◽  
The Cost

Navigation by the use of inertial information is now an accepted technique for military aircraft and for missiles. In civil aircraft the application of inertial techniques are, as yet, limited to defining the vertical and providing a memory of azimuth direction; that is, as aids to flight rather than a primary or even sole navigational aid. Although the principles applied—the inertial properties of matter and the laws of gravitation—are the same, the accuracy of the inertial sensors differs by some three orders of magnitude, and the cost by some two orders, between these two extremes.Mr. A. Stratton of the Royal Aircraft Establishment first of all presents in perspective the range of application of inertial techniques that are available for civil use and suggests how the information obtained by inertial means can be related to that from other airborne sources. He shows that even if the expense of an accurate inertial platform of ‘navigational’ quality should not be justified, considerable advantage over existing sources obtains in terms of accurate attitude reference, and instantaneous velocity and acceleration, by the use of a lower-grade platform in conjunction with other navigation aids.

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