A Spatial Data Model for Moving Object Databases

The objective of this project is to evaluate existing and emerging Open Geospatial Consortium (OGC) standards for use in LLNL programs that rely heavily on geographic data. OGC standards are intended to facilitate interoperability between geospatial processing systems to avoid duplication of effort, lower development costs, and encourage competition based on improved capability and performance rather than vendor lock-in. Some of these standards appear to be gaining traction in the geospatial data community, the Federal government, DOE and DHS. A serious evaluation of this technology is appropriate at this time due to increasing interest and mandated compliance in the Federal government in some situations. A subset of OGC standards is identified and reviewed with a focus on applications to LLNL programs. Each standard or recommendation reviewed was evaluated in general terms. In addition, for specific programs such as Gen&SIS and NARAC, a specific evaluation was made of several of the standards and how they could be used most effectively. It is also important to evaluate the acceptance of these standards in the commercial arena. The implementation of OGC standards by the largest GIS vendor (ESRI) was reviewed. At present, OGC standards are primary useful in specific situations. More generally, many of the standards are immature and their impact on the government and commercial sectors is unclear. Consequently, OGC and related developments need to be observed. As specific standards or groups of standards mature and establish their relevance, these can also be incorporated in LLNL programs as requirements dictate, especially if open implementations and commercial products are available.

Moving object database is a collection of geometric data that changing over time. The existence of a moving object database allows database users to express a series of predicates that state events or changes that happened during the movement of a moving object. The class of queries that involve a series of predicates is called the Spatio-temporal pattern (STP) queries. STP query has temporal order constraints on the fulfillment of predicates involved. The implementation of the STP query is unavailable in existing database management systems (DBMSs). Developing a tool to express the STP query needs to be done. This is to allow any kind of questions that could not be asked before.STP query is expressed using the STP predicate which has a design consisting of two parts. The first defines lifted predicates that accept moving object arguments and report the time intervals, during which they are fulfilled. The second part is to define temporal constraints on the predicate fulfillments. Temporal constraints are defined as temporal relationships between pairs of time intervals.Implementation of STP queries is done by providing data structures for moving objects, methods for evaluating operations on moving objects, and functions for defining STP predicates. The implementation is collected into a single package called extension. Extension is a form of tool built on the DBMS to handles STP queries in a moving object database. The extension is built on PostgreSQL which provides spatial data types and operations through PostGIS. The testing of the tool is done by executing several STP queries. The test results show that the tool built successfully handles STP queries in a moving object database.

Moving objects databases (MOD) have been receiving increasing attention from the database community in recent years, mainly due to the wide variety of applications that technology allows nowadays. Trajectories of moving objects like cars or pedestrians, can be reconstructed by means of samples describing the locations of these objects at certain points in lime. Although there are many proposals for modeling and querying moving objects, only a small part of them address the problem of aggregation of moving objects data in a GIS (Geographic Information Systems) scenario. In previous work we presented a formal model where the geometric components of the thematic layers in a GIS are represented as an OLAP (On Line Analytical Processing) dimension hierarchy, and introduced the notion of spatial aggregation. In this paper we extend this proposal in order to address moving object aggregation over a GIS. In this way. complex aggregate queries can be expressed in an elegant fashion. We present the data model, characterize the kinds of queries that may appear in this scenario, and show how these queries can be expressed as an aggregation over the result given by a first order formula expressing constraints over the geometries of the layers.

This work presents the development of an efficient tool for managing, visualizing, analysing, and integrating with other data sources, the deformation time-series obtained by applying the advanced differential interferometric synthetic aperture radar (DInSAR) techniques. To implement such a tool we extend the functionalities of GeoNode, which is a web-based platform providing an open source framework based on the Open Geospatial Consortium (OGC) standards, that allows development of Geospatial Information Systems (GIS) and Spatial Data Infrastructures (SDI). In particular, our efforts have been dedicated to enable the GeoNode platform to effectively analyze and visualize the spatio/temporal characteristics of the DInSAR deformation time-series and their related products. Moreover, the implemented multi-thread based new functionalities allow us to efficiently upload and update large data volumes of the available DInSAR results into a dedicated geodatabase. The examples we present, based on Sentinel-1 DInSAR results relevant to Italy, demonstrate the effectiveness of the extended version of the GeoNode platform.

Location tracking applications which receives frequent updates of a moving object's position, collect numerous moving objects' location data. Public transit agencies can make use of tracking data to optimize traffic control strategies. While improper use of trajectory data could cause individuals' privacy leakage. However, existing privacy-preserving techniques are unable to provide sufficient privacy protection. In this paper, we propose a data-dependent differentially private sanitization algorithm to publish moving object database. Moreover, we make use of a set of real-world constraints to conduct constraint inference, which can boost the utility of the published data. At last, we experimentally evaluate the utility of the sanitized data in terms of range-count queries, results show high utility and efficiency of our proposal.

Moving Object Databases (MODs), the core component of location server to support location-related applications, keep track of the locations of moving objects which submit location update reports to the centralized server. In resource-limited wireless environments, the frequency and conditions for generating location update messages exert a strong impact on system performance in terms of update message cost and object location accuracy, hence the query result precision. Conceptually, moving objects are the sources of the location data while the MOD caches recently reported object locations for query processing. Owing to the inherent imprecision of the cached values, we impose a bounded level of inconsistency for the cached values, realized in the form of a for a moving object. The cached value needs not be invalidated so long as the deviation of the object?s current location from its reported location is within the safe range. A smaller safe range results in a higher accuracy of the cached value and hence more accurate query result at the expense of higher update cost, and vice versa. Since the size of the safe range is the key to system performance, we derive a system cost model to determine its appropriate value. Furthermore, to cater for highly dynamic environments in which object movement, query access pattern and system workload always change, we propose two adaptive safe range adjustment algorithms. Through extensive simulation experiments, the benefits brought about by our algorithms are evidenced.

Moving object databases are required to support different types of queries with a large number of moving objects. New types of queries namely directions and velocity queries (DV queries), are to be supported and covered. The TPR-tree and its successors are efficient indexes that support spatio-temporal queries for moving objects. However, neither of them support the new DV queries. In this paper, we propose a new index for moving objects based on the TPR*-tree, named Direction and Velocity of TPR*-tree or DV-TPR*-tree, in order to build data a structure based on the spatial, direction and velocity domains. DV-TPR*-tree obtains an ideal distribution that supports and fulfils the new query types (DV queries). Extensive performance studies show that the query performance of DV-TPR*-tree outperforms the TPR-tree and its successors.

In this paper, a new moving objects database model, Route-based model for Moving Objects on Dynamic Transportation Networks (RMODTN), is proposed which is suited for dealing with the interrelationship between moving objects and the underlying transportation networks. The data model is given as a collection of data types and operations which can be plugged into a DBMS to obtain a complete data model and query language. Besides, an index framework for network-constrained moving objects is provided, which can deal with the full dynamic trajectories of network-constrained moving objects so that the queries on the whole life span of the moving objects can be efficiently supported. To evaluate the performance of the proposed methods, we have implemented RMODTN on PostgreSQL and conducted a series of experiments. The experimental results show quite satisfying query processing performances.

For bridging the gap between information retrieval (IR) and databases (DB), this article focuses on the logical view. We claim that IR should adopt three major concepts from DB, namely inference, vague predicates and expressive query languages. By regarding IR as uncertain inference, probabilistic versions of relational algebra and Datalog yield very powerful inference mechanisms for IR as well as allowing for more flexible systems. For dealing with various media and data types, vague predicates form a natural extension of text retrieval methods to attribute values, thus switching from propositional to predicate logic. A more expressive IR query language should support joins, be able to compute aggregated results, and allow for restructuring of the result objects.

IoT, EO and the Web are providing ever increasing amounts of geospatial information. In order to access and integrate the data using geospatial and temporal methods, standards are needed. This paper provides a summary of current capabilities and recent advancements in standards from the Open Geospatial Consortium (OGC) that provide these capabilities.

Moving object tracking and status update strategy is one of the most important factors that affect the performance of moving objects databases (MOD). In this paper, based on motion vectors and the characteristics of ship navigation information, we propose an update strategy for the ship navigation moving objects databases. By experiments, we compare the real ship voyage trajectory with the rebuild trajectory by using the ship navigation moving objects database. Experiments show that our update mechanism has better performance in low communication cost and high accuracy.

Open source REST services for environmental sensor networking

The applications of Geographic Information System (GIS) in the education sector are increasing day by day. The geospatial information can be published, discovered, searched, analyzed, and displayed through webGIS-based applications. Lack of an open source geospatial resource-based platform for data sharing, discovery, and service delivery in the education sector is a critical issue in managing the education of large population in India. The use of open geospatial consortium (OGC) developed open standards for geospatial web services will result in the interoperability of geographic information. In this paper, an interoperable and secure service-oriented architecture (SOA)-based webGIS framework is developed to handle the technical and non-technical issues in the education sector. In this research work, spatial analysis on schools is performed along with the design and development of webGIS framework using SOA, OGC standards, and open source software. The developed webGIS framework, acronym as EduGIS, is interoperable and secure which is implemented for the education sector. The development of webGIS framework is based upon three-tier thin client architecture. The present research work has investigated an optimized adoption of various free and open source software like Quantum GIS, GeoServer, Apache Tomcat, PostGIS, and uDig in different tiers of developed webGIS framework. The interoperability of developed EduGIS ensures that it can be shared across different technologies, data, platforms, and organizations. The development of open source-based webGIS framework will serve as a means of reducing licensing costs in developing countries like India and will promote indigenous technological development for primary education in rural areas.

This paper describes the history, background, and current status of the Open Geospatial Consortium (OGC) standards development consensus process. The roots of the formation of the OGC lie in the early 1990s when a very strong market requirement for exchanging GIS data content was clearly stated. At that time, each GIS vendor had their own formats for publishing and/or exchanging their GIS data. There was no mechanism or organization that provided a forum for the GIS vendors and GIS data users to collaborate and agree on how to share GIS data. That requirement, along with the vision of a few individuals, led to the formation of the OGC. This paper describes the early development of the consensus process in the OGC, how this process has evolved over time, why consensus is so important for defining open standards that are implemented in the marketplace, and the future of the OGC consensus process.

This article intends to provide an advanced traveller information system based on open geospatial consortium (OGC) standards to perform a fuzzy bi-criteria shortest-path analysis for a multimodal transportation network. To do so, chaining of OGC web services is used to resolve interoperability problems among distributed and heterogeneous resource data. First, a web feature service is assigned to each mode of transportation to gather and convert the data to a standard format, such as geographic markup language. Then, the obtained data are combined to model and construct the multimodal transportation network. Subsequently, a web processing service is designed for performing a fuzzy bi-criteria shortest-path analysis in the multimodal transportation network. Finally, the best routes between the origin–destination pair are presented on a digital map by using a web map service. In the study, among various route-selection criteria, travel time and comfort are considered. To model these criteria, the fuzzy set theory is utilized. By using fuzzy decision tables and a Tsukamoto fuzzy inference system, the desirability of the routes is calculated. The results of comparison among the four travel routes between various origin–destination pairs indicate that the proposed system could be an applicable tool for providing pre-trip information and assisting multimodal travellers under uncertain conditions.