共查询到20条相似文献，搜索用时 15 毫秒
1.
Can Yang Győző Gidófalvi 《International journal of geographical information science》2018,32(3):547-570
Wide deployment of global positioning system (GPS) sensors has generated a large amount of data with numerous applications in transportation research. Due to the observation error, a map matching (MM) process is commonly performed to infer a path on a road network from a noisy GPS trajectory. The increasing data volume calls for the design of efficient and scalable MM algorithms. This article presents fast map matching (FMM), an algorithm integrating hidden Markov model with precomputation, and provides an open-source implementation. An upper bounded origin-destination table is precomputed to store all pairs of shortest paths within a certain length in the road network. As a benefit, repeated routing queries known as the bottleneck of MM are replaced with hash table search. Additionally, several degenerate cases and a problem of reverse movement are identified and addressed in FMM. Experiments on a large collection of real-world taxi trip trajectories demonstrate that FMM has achieved a considerable single-processor MM speed of 25,000–45,000 points/second varying with the output mode. Investigation on the running time of different steps in FMM reveals that after precomputation is employed, the new bottleneck is located in candidate search, and more specifically, the projection of a GPS point to the polyline of a road edge. Reverse movement in the result is also effectively reduced by applying a penalty. 相似文献
2.
Xue Yang Kathleen Stewart Zhen Dong Xia Zhang Qingquan Li 《International journal of geographical information science》2018,32(3):601-621
Lane-level road network updating is crucial for urban traffic applications that use geographic information systems contributing to, for example, intelligent driving, route planning and traffic control. Researchers have developed various algorithms to update road networks using sensor data, such as high-definition images or GPS data; however, approaches that involve change detection for road networks at lane level using GPS data are less common. This paper presents a novel method for automatic change detection of lane-level road networks based on GPS trajectories of vehicles. The proposed method includes two steps: map matching at lane level and lane-level change recognition. To integrate the most up-to-date GPS data with a lane-level road network, this research uses a fuzzy logic road network matching method. The proposed map-matching method starts with a confirmation of candidate lane-level road segments that use error ellipses derived from the GPS data, and then computes the membership degree between GPS data and candidate lane-level segments. The GPS trajectory data is classified into successful or unsuccessful matches using a set of defuzzification rules. Any topological and geometrical changes to road networks are detected by analysing the two kinds of matching results and comparing their relationships with the original road network. Change detection results for road networks in Wuhan, China using collected GPS trajectories show that these methods can be successfully applied to detect lane-level road changes including added lanes, closed lanes and lane-changing and turning rules, while achieving a robust detection precision of above 80%. 相似文献
3.
Hengfeng Li Lars Kulik Kotagiri Ramamohanarao 《International journal of geographical information science》2013,27(12):2194-2222
Monitoring and predicting traffic conditions are of utmost importance in reacting to emergency events in time and for computing the real-time shortest travel-time path. Mobile sensors, such as GPS devices and smartphones, are useful for monitoring urban traffic due to their large coverage area and ease of deployment. Many researchers have employed such sensed data to model and predict traffic conditions. To do so, we first have to address the problem of associating GPS trajectories with the road network in a robust manner. Existing methods rely on point-by-point matching to map individual GPS points to a road segment. However, GPS data is imprecise due to noise in GPS signals. GPS coordinates can have errors of several meters and, therefore, direct mapping of individual points is error prone. Acknowledging that every GPS point is potentially noisy, we propose a radically different approach to overcome inaccuracy in GPS data. Instead of focusing on a point-by-point approach, our proposed method considers the set of relevant GPS points in a trajectory that can be mapped together to a road segment. This clustering approach gives us a macroscopic view of the GPS trajectories even under very noisy conditions. Our method clusters points based on the direction of movement as a spatial-linear cluster, ranks the possible route segments in the graph for each group, and searches for the best combination of segments as the overall path for the given set of GPS points. Through extensive experiments on both synthetic and real datasets, we demonstrate that, even with highly noisy GPS measurements, our proposed algorithm outperforms state-of-the-art methods in terms of both accuracy and computational cost. 相似文献
4.
Zhe Zeng Tong Zhang Qingquan Li Zhongheng Wu Haixiang Zou Chunxian Gao 《International journal of geographical information science》2016,30(4):660-690
Map matching method is a fundamental preprocessing technique for massive probe vehicle data. Various transportation applications need map matching methods to provide highly accurate and stable results. However, most current map matching approaches employ elementary geometric or topological measures, which may not be sufficient to encode the characteristic of realistic driving paths, leading to inefficiency and inaccuracy, especially in complex road networks. To address these issues, this article presents a novel map matching method, based on the measure of curvedness of Global Positioning System (GPS) trajectories. The curvature integral, which measures the curvedness feature of GPS trajectories, is considered to be one of the major matching characteristics that constrain pairwise matching between the two adjacent GPS track points. In this article, we propose the definition of the curvature integral in the context of map matching, and develop a novel accurate map matching algorithm based on the curvedness feature. Using real-world probe vehicles data, we show that the curvedness feature (CURF) constrained map matching method outperforms two classical methods for accuracy and stability under complicated road environments. 相似文献
5.
监测和预测冰盖的行为和演化趋势对于研究未来全球气候及海平面变化具有重要的科学意义。地球物理探测成为极地现场考察中最重要的技术手段并取得巨大成功,而航空地球物理的独特优势成为极地科考最有发展潜力的研究方向。经过多年努力,中国成为第4个拥有极地航空地球物理科学考察能力的国家,并在中国第32次南极考察期间完成东南极伊丽莎白公主地(PEL)数千平方千米的航空地球物理探测任务。对于航空地球物理勘探而言,航空测点定位是首要而基础性的工作,本文针对航空地球物理测量中GPS定位数据后处理工作目标,通过一系列的方法和软件对比试验,评价GPS后处理精度误差和应用效果,在试验基础上开发相应的软件完成GPS数据和各地球物理方法数据的匹配连接,进而总结极地航空地球物理GPS数据后处理工作流程,形成实用化的极地航空地球物理GPS数据后处理方案,对后续工作具有指导意义。 相似文献
6.
Aengus McCullough Philip James Stuart Barr 《International journal of geographical information science》2013,27(10):1939-1957
The geospatial sensor web is set to revolutionise real-time geospatial applications by making up-to-date spatially and temporally referenced data relating to real-world phenomena ubiquitously available. The uptake of sensor web technologies is largely being driven by the recent introduction of the OpenGIS Sensor Web Enablement framework, a standardisation initiative that defines a set of web service interfaces and encodings to task and query geospatial sensors in near real time. However, live geospatial sensors are capable of producing vast quantities of data over a short time period, which presents a large, fluctuating and ongoing processing requirement that is difficult to adequately provide with the necessary computational resources. Grid computing appears to offer a promising solution to this problem but its usage thus far has primarily been restricted to processing static as opposed to real-time data sets. A new approach is presented in this work whereby geospatial data streams are processed on grid computing resources. This is achieved by submitting ongoing processing jobs to the grid that continually poll sensor data repositories using relevant OpenGIS standards. To evaluate this approach a road-traffic monitoring application was developed to process streams of GPS observations from a fleet of vehicles. Specifically, a Bayesian map-matching algorithm is performed that matches each GPS observation to a link on the road network. The results show that over 90% of observations were matched correctly and that the adopted approach is capable of achieving timely results for a linear time geoprocessing operation performed every 60 seconds. However, testing in a production grid environment highlighted some scalability and efficiency problems. Open Geospatial Consortium (OGC) data services were found to present an IO bottleneck and the adopted job submission method was found to be inefficient. Consequently, a number of recommendations are made regarding the grid job-scheduling mechanism, shortcomings in the OGC Web Processing Service specification and IO bottlenecks in OGC data services. 相似文献
7.
Kivanc Ertugay Sebnem Duzgun 《International journal of geographical information science》2013,27(9):1491-1506
The term physical accessibility has long been used by geographers, economists, and urban planners and reflects the relative ease of access to/from several urban/rural services by considering the traveling costs. Numerous accessibility measures, ranging from simple to sophisticated, can be observed in the geographical information systems (GIS)-based accessibility modeling literature. However, these measures are generally calculated from a constant catchment boundary (a most likely or average catchment boundary) based on constant deterministic transportation costs. This is one of the fundamental shortcomings of the current GIS-based accessibility modeling and creates uncertainty about the accuracy and reliability of the accessibility measures, especially when highly variable speeds in road segments are considered. The development of a new stochastic approach by using global positioning system (GPS)-based floating car data and Monte Carlo simulation (MCS) technique could enable handling the variations in transportation costs in a probabilistic manner and help to consider all possible catchment boundaries, instead of one average catchment boundary, in accessibility modeling process. Therefore, this article proposes a stochastic methodology for GIS-based accessibility modeling by using GPS-based floating car data and MCS technique. The proposed methodology is illustrated with a case study on medical emergency service accessibility in Eskisehir, Turkey. Moreover, deterministic and stochastic accessibility models are compared to demonstrate the differences between the models. The proposed model could provide better decision support for the decision-makers who are supposed to deal with accessibility, location/allocation, and service/catchment area related issues. 相似文献
8.
利用北斗/GPS双系统四频率接收机,于2011年10月至2012年4月采集了中国第28次南极考察沿线的北斗和GPS实测数据,跨度北至中国天津,南至南极内陆昆仑站。从C/A码伪距的信噪比和多路径、可见卫星数、PDOP值、标准定位的精度等方面对比分析了北斗和GPS系统在航线上不同区域,尤其是在远洋及南极地区不同运动状态下的定位效果。结果表明现阶段的北斗系统信号质量总体上与GPS相当;在45°以内的中低纬度地区,动态定位精度与GPS相当,水平和高程方向分别可达10 m和20 m左右,而静态定位水平方向精度为米级,与GPS相当,高程方向10 m左右,较GPS略差;在中高纬地区,由于可见卫星数较少、卫星分布较差,定位精度较差或无法定位。 相似文献
9.
Andrej Osterman Lucas Benedičič Patrik Ritoša 《International journal of geographical information science》2014,28(11):2304-2327
A rapid and flexible parallel approach for viewshed computation on large digital elevation models is presented. Our work is focused on the implementation of a derivate of the R2 viewshed algorithm. Emphasis has been placed on input/output (IO) efficiency that can be achieved by memory segmentation and coalesced memory access. An implementation of the parallel viewshed algorithm on the Compute Unified Device Architecture (CUDA), which exploits the high parallelism of the graphics processing unit, is presented. This version is referred to as r.cuda.visibility. The accuracy of our algorithm is compared to the r.los R3 algorithm (integrated into the open-source Geographic Resources Analysis Support System geographic information system environment) and other IO-efficient algorithms. Our results demonstrate that the proposed implementation of the R2 algorithm is faster and more IO efficient than previously presented IO-efficient algorithms, and that it achieves moderate calculation precision compared to the R3 algorithm. Thus, to the best of our knowledge, the algorithm presented here is the most efficient viewshed approach, in terms of computational speed, for large data sets. 相似文献
10.
"雪龙"号破冰船是我国目前唯一的极地考察船,破冰航行是极地船舶的重要特征之一。以"雪龙"号破冰船的GPS数据为基础,通过建立模型算法识别冲击式破冰这一特殊的航行状态,在整个中国第28次南极考察航次的数据分析中,整体识别率超过86.1%,识别正确率达到98%以上。利用此算法,在中国第27次南极考察航次的破冰识别率也超过85%,识别正确率达到93.5%。雪龙船两个航次实测GPS数据验证了本文算法的可用性,而破冰识别统计结果表明,不同航次的破冰模式具有较大的差异。 相似文献
11.
针对BRISK算法在喀斯特山区无人机影像匹配中存在耗时长、正确匹配点数较少的问题,该文提出一种基于BRISK检测子和LATCH描述符的喀斯特山区无人机影像匹配算法,即利用BRISK检测子对影像进行特征点检测,利用LATCH描述符描述特征点,并采用结合最小距离的FLANN算法进行粗匹配,最后利用RANSAC算法对影像进行精匹配,剔除粗匹配中的错误匹配点对。实验结果表明:该算法的匹配总数和正确点数是SIFT和AKAZE算法的2倍以上,单点平均耗时是二者的7%~80%;与BRISK算法相比,在匹配总数减少5%的情况下,该算法的正确点数增加了30%以上,单点平均耗时减少50%以上。 相似文献
12.
电离层时延为GPS测量中最棘手、最严重的误差源,而极区结构复杂波动较大,电离层延迟极大影响了GPS测量精度,故在极区选取一个简单有效的电离层模型极为重要。将GPS及BDS采用的不同Klobuchar模型以及Ne Quick模型计算的极区总电子含量,以欧洲定轨中心提供的GIM模型电离层产品作为参考标准,研究三种广播电离层模型在北极地区的均方根和模型改正率。选取了2009—2013年共计5年的时间数据进行分析。结果表明,纬度在57.5°以上地区电离层改正GPS系统采用的Klobuchar模型基本不适用,但改正效果依然优于BDS,而Ne Quick模型改正效果弱于中低纬度,改正率整体在40%左右。 相似文献
13.
自2005年以来,我国科考队员利用双频GPS在北极黄河站附近的Austre Lovénbreen 和 Pedersenbreen两条冰川上每年一次开展高精度的冰川运动观测,获取了冰川表面监测标杆的精确位置和运动速度。2009年4月,我国考察队员在这两条冰川上开展了密集的GPS点位数据采集,藉此开展北极两条冰川的冰面地形测量。在分析单频GPS动态单点定位数据用于冰面地形测量的可行性基础上,经过平差计算获得了两条冰川的冰面地形数据,进而生成冰面DEM和等高线,制作冰面地形图。经与高精度控制点比较,冰面DEM高程的误差为0.78m,在冰川季节性高程波动和年消融的变化范围之内。由于SMART-V1型GPS设备是当前冰川研究工作中应用较多的pulseEKKO型探地雷达配套的一个重要部件,本文的结论对于同类仪器开展冰川测量工作具有参考价值,对基于高密度的GPS动态单点定位测量方法用于冰面地形测量的数据处理具有指导意义。 相似文献
14.
David C. Folch Seth E. Spielman 《International journal of geographical information science》2014,28(1):164-184
The identification of regions is both a computational and conceptual challenge. Even with growing computational power, regionalization algorithms must rely on heuristic approaches in order to find solutions. Therefore, the constraints and evaluation criteria that define a region must be translated into an algorithm that can efficiently and effectively navigate the solution space to find the best solution. One limitation of many existing regionalization algorithms is a requirement that the number of regions be selected a priori. The recently introduced max-p algorithm does not have this requirement, and thus the number of regions is an output of, not an input to, the algorithm. In this paper, we extend the max-p algorithm to allow for greater flexibility in the constraints available to define a feasible region, placing the focus squarely on the multidimensional characteristics of the region. We also modify technical aspects of the algorithm to provide greater flexibility in its ability to search the solution space. Using synthetic spatial and attribute data, we are able to show the algorithm’s broad ability to identify regions in maps of varying complexity. We also conduct a large-scale computational experiment to identify parameter settings that result in the greatest solution accuracy under various scenarios. The rules of thumb identified from the experiment produce maps that correctly assign areas to their ‘true’ region with 94% average accuracy, with nearly 50% of the simulations reaching 100% accuracy. 相似文献
15.
《The Journal of geography》2012,111(5):186-193
Abstract This paper introduces global positioning system (GPS) technology to nonspecialist geographers and recommends a framework for implementing GPS instructional modules in college geography courses. The GPS system was developed as a worldwide satellite-based system by the U.S. Department of Defense (DoD) to simplify and improve military and civilian navigation and positioning. By presenting GPS in several courses, the approach outlined can expose large numbers of students to GPS and may help to demonstrate the utility of GPS for several geographic subdisciplines. 相似文献
16.
Dieudonné Tsatcha Éric Saux Christophe Claramunt 《International journal of geographical information science》2014,28(7):1355-1377
Route planning is an important problem for many real-time applications in open and complex environments. The maritime domain is a relevant example of such environments where dynamic phenomena and navigation constraints generate difficult route finding problems. This paper develops a spatial data structure that supports the search for an optimal route between two locations while minimizing a cost function. Although various search algorithms have been proposed so far (e.g. breadth-first search, bidirectional breadth-first search, Dijkstra’s algorithm, A*, etc.), this approach provides a bidirectional dynamic routing algorithm which is based on hexagonal meshes and an iterative deepening A* (IDA*) algorithm, and a front to front strategy using a dynamic graph that facilitates data accessibility. The whole approach is applied to the context of maritime navigation, taking into account navigation hazards and restricted areas. The algorithm developed searches for optimal routes while minimizing distance and computational time. 相似文献
17.
E. Safra Y. Kanza Y. Sagiv Y. Doytsher 《International journal of geographical information science》2013,27(1):114-153
In integration of road maps modeled as road vector data, the main task is matching pairs of objects that represent, in different maps, the same segment of a real-world road. In an ad hoc integration, the matching is done for a specific need and, thus, is performed in real time, where only a limited preprocessing is possible. Usually, ad hoc integration is performed as part of some interaction with a user and, hence, the matching algorithm is required to complete its task in time that is short enough for human users to provide feedback to the application, that is, in no more than a few seconds. Such interaction is typical of services on the World Wide Web and to applications in car-navigation systems or in handheld devices. Several algorithms were proposed in the past for matching road vector data; however, these algorithms are not efficient enough for ad hoc integration. This article presents algorithms for ad hoc integration of maps in which roads are represented as polylines. The main novelty of these algorithms is in using only the locations of the endpoints of the polylines rather than trying to match whole lines. The efficiency of the algorithms is shown both analytically and experimentally. In particular, these algorithms do not require the existence of a spatial index, and they are more efficient than an alternative approach based on using a grid index. Extensive experiments using various maps of three different cities show that our approach to matching road networks is efficient and accurate (i.e., it provides high recall and precision). General Terms:Algorithms, Experimentation 相似文献
18.
GNSS 可提供全天候的实时高精度定位结果,是形变监测的主要方法之一,但卫星信号极易受到周围环境如建筑物、人群等遮挡的影响,而相当数量的基础设施修建于山谷、城市建筑群、车流密集等区域。文章研究在遮挡环境下卫星定位应用于形变监测领域的可行性问题。因中国北斗系统在星座布设上与GPS 不同,采用GEO、IGSO 及MEO 三种不同轨道类型形成高轨卫星与中轨卫星的结合,不同的轨道类型有不同的特点,对定位精度的影响也不尽相同。以广州大桥为例,通过对北斗/GPS 集成高精度定位的研究,并针对北斗卫星的不同轨道类型,利用GEO、IGSO 及MEO 之间的不同组合进行定位,分析其在形变监测的可行性。研究表明：北斗/GPS 集成高精度定位精度可达毫米级,能够满足形变监测的需求;同时,北斗/GPS 集成定位可增加可视卫星数,改善卫星的几何分布,而北斗系统的高轨卫星高度角较高,特别是GEO 和IGSO 两种高轨卫星的组合仍能达到1 cm 的定位精度,大大提高了山谷、高边坡、城市峡谷等遮挡较为严重区域中卫星高精度定位的可行性,有利于形成全天候自动化实时高精度的形变监测与灾害监测安全预警系统。 相似文献
19.
Timothy C. Matisziw Emre Demir 《International journal of geographical information science》2013,27(10):1979-1996
The use of geographically referenced point data, such as that obtained from global positioning systems (GPS), is rapidly increasing. However, due to error and uncertainty inherent in most geographic datasets, the ability to accurately associate these point locations with other layers of geographic data is still a challenge. One difficulty in particular is how to associate spatially and temporally referenced point-based observations of a network activity with a network topology such that a continuous network path can be best inferred. In this article, an optimization method for inferring a network path from a temporal sequence of point observations of location is presented. An application to GPS data is provided to highlight various characteristics of the proposed modeling approach relative to several other available techniques. 相似文献
20.