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Proceedings of the 20th International Conference on Advances in Geographic Information Systems最新文献

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Matching GPS traces to (possibly) incomplete map data: bridging map building and map matching 匹配GPS轨迹到(可能)不完整的地图数据:桥接地图构建和地图匹配
Fernando Torre, David Pitchford, Phil Brown, L. Terveen
Analysis of geographic data often requires matching GPS traces to road segments. Unfortunately, map data is often incomplete, resulting in failed or incorrect matches. In this paper, we extend an HMM map-matching algorithm to handle missing blocks. We test our algorithm using map data from the Cyclopath geowiki and GPS traces from Cyclopath's mobile app. Even for conservative cutoff distances, our algorithm found a significant amount of missing data per set of GPS traces. We tested the algorithm for accuracy by removing existing blocks from our map dataset. As the cutoff distance was lowered, false negatives were decreased from 34% to 16% as false positives increased from 5% to 10%. Although the algorithm degrades with increasing amounts of missing data, our results show that our extensions have the potential to improve both map matches and map data.
地理数据分析通常需要将GPS轨迹与路段相匹配。不幸的是,地图数据往往不完整,导致失败或不正确的匹配。在本文中,我们扩展了HMM映射匹配算法来处理缺失块。我们使用来自Cyclopath geowiki的地图数据和来自Cyclopath移动应用程序的GPS轨迹来测试我们的算法。即使对于保守的截止距离,我们的算法也发现了大量的GPS轨迹缺失数据。我们通过从地图数据集中删除现有块来测试算法的准确性。随着截止距离的降低,假阴性从34%下降到16%,假阳性从5%上升到10%。尽管该算法会随着丢失数据量的增加而退化,但我们的结果表明,我们的扩展具有改进地图匹配和地图数据的潜力。
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引用次数: 20
EcoMark: evaluating models of vehicular environmental impact ecommark:车辆环境影响评估模型
Chenjuan Guo, Yu Ma, B. Yang, Christian S. Jensen, Manohar Kaul
The reduction of greenhouse gas (GHG) emissions from transportation is essential for achieving politically agreed upon emissions reduction targets that aim to combat global climate change. So-called eco-routing and eco-driving are able to substantially reduce GHG emissions caused by vehicular transportation. To enable these, it is necessary to be able to reliably quantify the emissions of vehicles as they travel in a spatial network. Thus, a number of models have been proposed that aim to quantify the emissions of a vehicle based on GPS data from the vehicle and a 3D model of the spatial network the vehicle travels in. We develop an evaluation framework, called EcoMark, for such environmental impact models. In addition, we survey all eleven state-of-the-art impact models known to us. To gain insight into the capabilities of the models and to understand the effectiveness of the EcoMark, we apply the framework to all models.
减少交通运输产生的温室气体(GHG)排放对于实现旨在应对全球气候变化的政治上商定的减排目标至关重要。所谓的生态路线和生态驾驶能够大大减少车辆运输造成的温室气体排放。为了实现这些目标,有必要能够可靠地量化车辆在空间网络中行驶时的排放量。因此,已经提出了一些模型,旨在基于车辆的GPS数据和车辆行驶的空间网络的3D模型来量化车辆的排放量。我们为这样的环境影响模型开发了一个评估框架,称为EcoMark。此外,我们调查了我们所知道的所有11个最先进的影响模型。为了深入了解模型的功能并了解生态标志的有效性,我们将该框架应用于所有模型。
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引用次数: 77
The SMO-index: a succinct moving object structure for timestamp and interval queries SMO-index:用于时间戳和间隔查询的简洁移动对象结构
M. Romero, N. Brisaboa, Michael A. Rodriguez
This paper presents the Succinct Moving Object Index (SMO - Index) that pursues efficiency in storage and time of query processing for timestamp and interval queries. The data structure stores data and index together in a compact manner reducing the need of using external memory. It is based on a K2-tree to store snapshots of objects' location at some time instants, and on a compact representation of the movement of objects between consecutive snapshots. The experimental evaluation shows that the SMO-Index overcomes MVR-Tree in space used and time cost when objects constantly move at similar speed.
本文提出了简洁移动对象索引(SMO - Index),该索引在时间戳和间隔查询中追求存储效率和查询处理时间。数据结构以紧凑的方式将数据和索引存储在一起,减少了使用外部内存的需要。它基于K2-tree来存储对象在某些时刻的位置快照,并基于连续快照之间对象运动的紧凑表示。实验评价表明,当目标以相似速度持续运动时,smoi - index在空间占用和时间消耗上都优于MVR-Tree。
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引用次数: 10
The single pixel GPS: learning big data signals from tiny coresets 单像素GPS:从微小的核心集中学习大数据信号
Dan Feldman, C. Sung, D. Rus
We present algorithms for simplifying and clustering patterns from sensors such as GPS, LiDAR, and other devices that can produce high-dimensional signals. The algorithms are suitable for handling very large (e.g. terabytes) streaming data and can be run in parallel on networks or clouds. Applications include compression, denoising, activity recognition, road matching, and map generation. We encode these problems as (k, m)-segment mean problems. Formally, we provide (1 + ε)-approximations to the k-segment and (k, m)-segment mean of a d-dimensional discrete-time signal. The k-segment mean is a k-piecewise linear function that minimizes the regression distance to the signal. The (k,m)-segment mean has an additional constraint that the projection of the k segments on Rd consists of only m ≤ k segments. Existing algorithms for these problems take O(kn2) and nO(mk) time respectively and O(kn2) space, where n is the length of the signal. Our main tool is a new coreset for discrete-time signals. The coreset is a smart compression of the input signal that allows computation of a (1 + ε)-approximation to the k-segment or (k,m)-segment mean in O(n log n) time for arbitrary constants ε,k, and m. We use coresets to obtain a parallel algorithm that scans the signal in one pass, using space and update time per point that is polynomial in log n. We provide empirical evaluations of the quality of our coreset and experimental results that show how our coreset boosts both inefficient optimal algorithms and existing heuristics. We demonstrate our results for extracting signals from GPS traces. However, the results are more general and applicable to other types of sensors.
我们提出了一种算法,用于简化和聚类来自传感器的模式,如GPS、激光雷达和其他可以产生高维信号的设备。这些算法适用于处理非常大(例如tb)的流数据,并且可以在网络或云上并行运行。应用包括压缩、去噪、活动识别、道路匹配和地图生成。我们将这些问题编码为(k, m)段均值问题。形式上,我们提供了d维离散时间信号的k段和(k, m)段均值的(1 + ε)-近似。k段均值是一个k分段线性函数,它最小化到信号的回归距离。(k,m)段均值有一个附加约束,即k段在Rd上的投影仅由m≤k段组成。这些问题的现有算法分别需要O(kn2)和nO(mk)时间和O(kn2)空间,其中n为信号的长度。我们的主要工具是一个新的离散时间信号的核心。核心集是输入信号的智能压缩,允许在O(n log n)时间内对任意常数ε,k和m计算k段或(k,m)段均值的(1 + ε)近似值。我们使用核心集获得一种并行算法,该算法一次扫描信号。每个点使用的空间和更新时间是log n的多项式。我们提供了对我们的核心集质量的经验评估和实验结果,显示了我们的核心集如何提高低效的最优算法和现有的启发式算法。我们展示了从GPS轨迹中提取信号的结果。然而,结果更普遍,适用于其他类型的传感器。
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引用次数: 24
Extracting significant places from mobile user GPS trajectories: a bearing change based approach 从移动用户GPS轨迹中提取重要位置:基于方位变化的方法
T. Bhattacharya, L. Kulik, J. Bailey
Moving object data, in particular of mobile users, is becoming widely available. A GPS trajectory of a moving object is a time-stamped sequence of latitude and longitude coordinates. The analysis and extraction of knowledge from GPS trajectories is important for a range of applications. Existing studies have extracted knowledge from trajectory patterns for both single and multiple GPS trajectories. However, few works have taken into account the unreliability of GPS measurements for mobile devices or focused on the extraction of fine-grained events from a user's GPS trajectory, such as waiting in traffic, at an intersection, or at a bus stop. In this paper, we develop and experimentally evaluate a novel algorithm that analyses a mobile user's bearing change distribution, together with speed and acceleration, to extract significant places of events from their GPS trajectory.
移动对象的数据,特别是移动用户的数据,正在变得广泛可用。移动物体的GPS轨迹是一个带有时间戳的经纬度坐标序列。从GPS轨迹中分析和提取知识对于一系列应用都很重要。现有的研究从单个和多个GPS轨迹的轨迹模式中提取知识。然而,很少有作品考虑到移动设备的GPS测量的不可靠性,或者专注于从用户的GPS轨迹中提取细粒度事件,例如在交通中等待,在十字路口,或在公共汽车站。在本文中,我们开发并实验评估了一种新的算法,该算法分析移动用户的方位变化分布,以及速度和加速度,以从其GPS轨迹中提取事件的重要位置。
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引用次数: 43
Location-based and preference-aware recommendation using sparse geo-social networking data 使用稀疏地理社交网络数据的基于位置和偏好感知的推荐
Jie Bao, Yu Zheng, M. Mokbel
The popularity of location-based social networks provide us with a new platform to understand users' preferences based on their location histories. In this paper, we present a location-based and preference-aware recommender system that offers a particular user a set of venues (such as restaurants) within a geospatial range with the consideration of both: 1) User preferences, which are automatically learned from her location history and 2) Social opinions, which are mined from the location histories of the local experts. This recommender system can facilitate people's travel not only near their living areas but also to a city that is new to them. As a user can only visit a limited number of locations, the user-locations matrix is very sparse, leading to a big challenge to traditional collaborative filtering-based location recommender systems. The problem becomes even more challenging when people travel to a new city. To this end, we propose a novel location recommender system, which consists of two main parts: offline modeling and online recommendation. The offline modeling part models each individual's personal preferences with a weighted category hierarchy (WCH) and infers the expertise of each user in a city with respect to different category of locations according to their location histories using an iterative learning model. The online recommendation part selects candidate local experts in a geospatial range that matches the user's preferences using a preference-aware candidate selection algorithm and then infers a score of the candidate locations based on the opinions of the selected local experts. Finally, the top-k ranked locations are returned as the recommendations for the user. We evaluated our system with a large-scale real dataset collected from Foursquare. The results confirm that our method offers more effective recommendations than baselines, while having a good efficiency of providing location recommendations.
基于位置的社交网络的流行为我们提供了一个新的平台,可以根据用户的位置历史来了解他们的偏好。在本文中,我们提出了一个基于位置和偏好感知的推荐系统,该系统为特定用户提供地理空间范围内的一组场所(如餐馆),同时考虑:1)用户偏好,这是从她的位置历史中自动学习的;2)社会意见,这是从当地专家的位置历史中挖掘的。这个推荐系统不仅可以方便人们在自己的居住地附近旅行,还可以方便人们到一个陌生的城市旅行。由于用户只能访问有限数量的位置,用户位置矩阵非常稀疏,这给传统的基于协同过滤的位置推荐系统带来了很大的挑战。当人们去一个新的城市旅行时,这个问题变得更加具有挑战性。为此,我们提出了一种新的位置推荐系统,该系统主要由离线建模和在线推荐两部分组成。离线建模部分使用加权类别层次(WCH)对每个人的个人偏好进行建模,并根据每个人的位置历史使用迭代学习模型推断出城市中每个用户相对于不同类别位置的专业知识。在线推荐部分使用偏好感知的候选选择算法在符合用户偏好的地理空间范围内选择候选本地专家,然后根据所选本地专家的意见推断候选位置的分数。最后,将排名前k的地点作为推荐返回给用户。我们用从Foursquare收集的大规模真实数据集来评估我们的系统。结果表明,该方法比基线推荐更有效,同时具有良好的位置推荐效率。
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引用次数: 707
Fast generation of multiple resolution instances of raster data sets 快速生成栅格数据集的多个分辨率实例
L. Arge, H. Haverkort, Constantinos Tsirogiannis
In many GIS applications it is important to study the characteristics of a raster data set at multiple resolutions. Often this is done by generating several coarser resolution rasters from a fine resolution raster. In this paper we describe efficient algorithms for different variants of this problem. Given a raster G of √N × √N cells we first consider the problem of computing for every 2 ≤ μ ≤ √N a raster Gμ of √N/μ × √N/μ cells such that each cell of Gμ stores the average of the values of μ × μ cells of G. We describe an algorithm that solves this problem in Θ(N) time when the handled data fit in the main memory of the computer. We also provide two algorithms that solve this problem in external memory, that is when the input raster is larger than the main memory. The first external algorithm is very easy to implement and requires O(sort(N)) data block transfers from/to the external memory, and the second algorithm requires only O(scan(N)) transfers, where sort(N) and scan(N) are the number of transfers needed to sort and scan N elements, respectively. We also study a variant of the problem where instead of the full input raster we handle only a connected subregion of arbitrary shape. For this variant we describe an algorithm that runs in Θ(U log N) time in internal memory, where U is the size of the output. We show how this algorithm can be adapted to perform efficiently in the external memory using O(sort(U)) data transfers from the disk. We have also implemented two of the presented algorithms, the O(sort(N)) external memory algorithm for full rasters, and the internal memory algorithm that handles connected subregions, and we demonstrate their efficiency in practice.
在许多GIS应用中,研究多分辨率栅格数据集的特征是很重要的。这通常是通过从一个精细分辨率光栅生成几个粗分辨率光栅来完成的。在本文中,我们描述了该问题的不同变体的有效算法。给定一个栅格G(√N ×√N cells),我们首先考虑对于每2≤μ≤√N个栅格G(√N/μ ×√N/μ cells)计算一个栅格G(√N/μ ×√N/μ cells)的问题,使得G的每个栅格存储G的μ × μ cells值的平均值。我们描述了一个算法,当处理的数据适合于计算机的主存储器时,在Θ(N)时间内解决这个问题。我们还提供了两种算法来解决外部存储器中的这个问题,即当输入栅格大于主存储器时。第一种外部算法非常容易实现,需要O(sort(N))个数据块从外部存储器传输到外部存储器,第二种算法只需要O(scan(N))个传输,其中sort(N)和scan(N)分别是排序和扫描N个元素所需的传输次数。我们还研究了该问题的一个变体,其中我们只处理任意形状的连接子区域,而不是完整的输入栅格。对于这种变体,我们描述了在内部内存中运行Θ(U log N)时间的算法,其中U是输出的大小。我们将展示如何使用从磁盘传输的O(sort(U))数据来调整该算法,以便在外部内存中高效执行。我们还实现了所提出的两种算法,即用于全光栅的O(sort(N))外部存储器算法和处理连接子区域的内部存储器算法,并在实践中证明了它们的效率。
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引用次数: 5
When a city tells a story: urban topic analysis 当一个城市讲述一个故事:城市话题分析
Felix Kling, A. Pozdnoukhov
This paper explores the use of textual and event-based citizen-generated data from services such as Twitter and Foursquare to study urban dynamics. It applies a probabilistic topic model to obtain a decomposition of the stream of digital traces into a set of urban topics related to various activities of the citizens in the course of a week. Due to the combined use of implicit textual and movement data, we obtain semantically rich modalities of the urban dynamics and overcome the drawbacks of several previous attempts. Other important advantages of our method include its flexibility and robustness with respect to the varying quality and volume of the incoming data. We describe an implementation architecture of the system, the main outputs of the analysis, and the derived exploratory visualisations. Finally, we discuss the implications of our methodology for enriching location-based services with real-time context.
本文探讨了使用Twitter和Foursquare等服务中基于文本和事件的公民生成数据来研究城市动态。它应用概率主题模型将数字轨迹流分解为一组与市民在一周内的各种活动相关的城市主题。由于隐式文本和运动数据的结合使用,我们获得了语义丰富的城市动态模式,并克服了之前几次尝试的缺点。我们的方法的其他重要优点包括它的灵活性和鲁棒性相对于不同的质量和数量的传入数据。我们描述了系统的实现架构,分析的主要输出,以及派生的探索性可视化。最后,我们讨论了用实时上下文丰富基于位置的服务的方法的含义。
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引用次数: 129
Mining time relaxed gradual moving object clusters 挖掘时间放松逐渐移动的目标簇
P. Hai, D. Ienco, P. Poncelet, M. Teisseire
One of the objectives of spatio-temporal data mining is to analyze moving object datasets to exploit interesting patterns. Traditionally, existing methods only focus on an unchanged group of moving objects during a time period. Thus, they cannot capture object moving trends which can be very useful for better understanding the natural moving behavior in various real world applications. In this paper, we present a novel concept of "time relaxed gradual trajectory pattern", denoted real-Gpattern, which captures the object movement tendency. Additionally, we also propose an efficient algorithm, called ClusterGrowth, designed to extract the complete set of all interesting maximal real-Gpatterns. Conducted experiments on real and large synthetic datasets demonstrate the effectiveness, parameter sensitiveness and efficiency of our methods.
时空数据挖掘的目标之一是分析运动对象数据集以挖掘有趣的模式。传统上,现有的方法只关注一段时间内一组不变的运动物体。因此,它们无法捕捉物体的移动趋势,而这对于更好地理解各种现实世界应用中的自然移动行为非常有用。本文提出了一种新的“时间放松渐进轨迹模式”的概念,称为real- g模式,它捕捉了物体的运动趋势。此外,我们还提出了一种称为ClusterGrowth的高效算法,用于提取所有有趣的最大real- g模式的完整集合。在真实数据集和大型合成数据集上进行的实验证明了我们的方法的有效性、参数敏感性和效率。
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引用次数: 12
Pricing of parking for congestion reduction 为减少挤塞而订定泊车收费
D. Ayala, O. Wolfson, Bo Xu, B. Dasgupta, Jie Lin
The proliferation of mobile devices, location-based services and embedded wireless sensors has given rise to applications that seek to improve the efficiency of the transportation system. In particular, new applications are already available that help travelers to find parking in urban settings by conveying the parking slot availability near the desired destinations of travelers on their mobile devices. In this paper we present two notions of parking choice: the optimal and the equilibrium. The equilibrium describes the behavior of individual, selfish agents in a system. We will show how a pricing authority can use the parking availability information to set prices that entice drivers to choose parking in the optimal way, the way that minimizes total driving distance by the vehicles and is then better for the transportation system (by reducing congestion) and for the environment. We will present two pricing schemes that perform this task. Furthermore, through simulations we show the potential congestion improvements that can be obtained through the use of these schemes.
移动设备、基于位置的服务和嵌入式无线传感器的激增,已经产生了寻求提高运输系统效率的应用。特别是,新的应用程序已经可以帮助旅行者在城市环境中找到停车位,通过在旅行者的移动设备上显示目的地附近的停车位可用性。本文提出了停车选择的两个概念:最优停车选择和均衡停车选择。均衡描述了系统中个体的、自私的行为主体的行为。我们将展示定价机构如何使用停车位可用性信息来设定价格,以吸引司机以最佳方式选择停车,这种方式可以最小化车辆的总行驶距离,从而对交通系统(通过减少拥堵)和环境更好。我们将提出执行此任务的两种定价方案。此外,通过模拟,我们展示了通过使用这些方案可以获得的潜在拥塞改善。
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引用次数: 73
期刊
Proceedings of the 20th International Conference on Advances in Geographic Information Systems
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