Laurent Etienne

Trajectory Box Plot: a new pattern to summarize movements

Nowadays, an abundance of sensors are used to collect very large datasets of moving objects. The movement of these objects can be analysed by identifying common routes. For this, a cluster of trajectories must be defined and the pattern of each cluster discovered. In this article, we introduce a new pattern, called the Trajectory Box Plot (TBP), to summarize a set of trajectories following the same route. The TBP is an extension of the well-known descriptive statistics Box Plot concept. Each TBP is described by a median trajectory, a 3D box and a 3D fence. The median trajectory depicts the typical movement of mobile objects. The box and the fences (whiskers) describe the spatial and temporal spreading around the central tendency. TBPs are useful to summarize and analyse trajectory streams, understand their spatio-temporal density and detect outliers. In this article, visual analysis highlights how the TBP pattern effectively describes how the density of trajectory clusters change over time.

Making sense of Arctic maritime traffic using the Polar Operational Limits Assessment Risk Indexing System (POLARIS)

Maritime traffic volume in the Arctic is growing for several reasons: climate change is resulting in less ice in extent, duration, and thickness; economic drivers are inducing growth in resource extraction traffic, community size (affecting resupply) and adventure tourism. This dynamic situation, coupled with harsh weather, variable operating conditions, remoteness, and lack of straightforward emergency response options, demand robust risk management processes. The requirements for risk management for polar ship operations are specified in the new International Maritime Organization (IMO) International Code for Ships Operating in Polar Waters (Polar Code). The goal of the Polar Code is to provide for safe ship operations and protection of the polar environment by addressing the risk present in polar waters. Risk management is supported by evidence-based models, including threat identification (types and frequency of hazards), exposure levels, and receptor characterization. Most of the information used to perform risk management in polar waters is attained in-situ, but increasingly is being augmented with open-access remote sensing information. In this paper we focus on the use of open-access historical ice charts as an integral part of northern navigation, especially for route planning and evaluation.

SmartLoire: A Web Mashup Based Tool for Personalized Touristic Plans Construction

A large set of Web services are nowadays available providing complementary content about: schedule of public transportation, description of touristic area, eteorological information, geocoding operations, etc. We present in this article a mobile-application prototype that mashups Web services to define custom touristic plans, i.e., takes into account tourist preferences (type of stay, interest) and constraints (duration, budget, locomotion modality). Moreover, the application considers real-time events (e.g., weather data or temporary unavailability of a touristic site) to adapt proposed schedules.

State of the Art in Patterns for Point Cluster Analysis

Nowadays, an abundance of sensors are used to collect very large datasets containing spatial points which can be mined and analyzed to extract meaningful patterns. In this article, we focus on different techniques used to summarize and visualize 2D point clusters and discuss their relative strengths. This article focuses on patterns which describe the dispersion of data around a central tendency. These techniques are particularly beneficial for detecting outliers and understanding the spatial density of point clusters.

From Sensing to Sense-Making: Assessing and Visualizing Ship Operational Limitations in the Canadian Arctic Using Open-Access Ice Data

Vessels planning a passage in the Canadian Arctic face many risks, most notably from ice, extreme weather, remoteness, and uncharted or poorly charted bathymetry. For ship operators who view the Arctic as a relatively untouched area of opportunity, the desire to operate vessels in the Arctic brings new challenges and risks. This study introduces the Polar Operational Limitations Assessment Risk Indexing System (POLARIS) and demonstrates its use for assessing ship operational limitations using open-access historical ice information. The analysis of ship operational limitations in ice was aided by the construction of POLARIS scenario risk maps which were clearly demonstrated as a useful tool to support the strategic appraisal of ice conditions. Lastly, several use cases are provided to demonstrate how POLARIS and historical ice information can be used to support the strategic appraisal of ship operational limitations in ice.

Optimized Discrete Fréchet Distance between trajectories

Distance computation between polylines or trajectories is a key point to assess similarity between geometrical objects. This paper describes a new optimized algorithm to compute discrete Fréchet distance which aims to lower computation time and improve precision. This algorithm is applied to GPS trajectories. It includes a filtering, pruning and an enhancement process. Thanks to this algorithm, big data trajectory repositories can be mined. This process is validated on a large trajectory dataset.

Oriented spatial box plot, a new pattern for points clusters

Nowadays, an abundance of sensors are used to collect very large datasets containing spatial points which can be mined and analysed to extract meaningful patterns and information. This article examines patterns which describe the dispersion of 2D data around a central tendency. Several state of the art patterns for point cluster analysis are presented and critiqued before a new pattern, the oriented spatial box plot, is defined. The oriented spatial box plot extends the classical one-dimensional box plot for summarising and visualising 2D point clusters. The pattern is suitable for detecting outliers and understanding the spatial density of point clusters.

Mesures de similarité de trajectoires basées sur l'utilisation de patrons spatio-temporels =

Mobile objects are now equipped with sensors allowing real time monitoring of their movements. Nowadays, the data produced by these sensors can be stored in spatio-temporal databases. Data mining on these stored positions allows to infer the behaviour of these mobile objects (spatio-temporal patterns) and to analyze positions and trajectories of mobile objects. Using these patterns, unusual situations can be detected. Two kinds of unusual situations are distinguished: unusual positions and unusual trajectories. This article defines similarity index based on spatial and temporal measures using fuzzy logic.