Gabriel Vatin

Urbanization of the United States over two centuries: an approach based on a long-term database 1790–2010

This paper presents an original methodology for the construction of a harmonized database for urban areas in the United States from 1790 to 2010 (a period with a census every 10 years, amounting to 23 dates). Upstream, this method is based on a theoretical choice, the use of a spatio-temporal reference frame to construct urban areas over the long term, defined by a maximum range of one hour’s travel for each period. We used an automatic aggregation from a Reilly model. Urban measures (growth, concentration) derived from this harmonized database are then presented, providing a unified picture of urbanization in the United States over more than two centuries. They are compared with results derived from more classical databases established using the official figures from the Census Bureau, or from other constructions differing from the present system. The results diverge considerably in some instances, which confirms the impact of the method of delineation of geographical areas in measures of growth.

La conduite du changement digital au défi de l'acceptabilité et de la sécurité

La finalite de cette communication est d’identifier un ensemble de facteurs pouvant causer l’echec de l’adoption d’une technologie innovante et la survenue d’une situation non souhaitee telle qu’un incident, un accident ou bien une crise. Les facteurs sont illustres avec le contexte de l’information geographique et une serie de questions est proposee afin de soutenir l’anticipation de situations non souhaitees lors de la conduite d’un projet d’innovation.

Using Ontologies for Proposing Adequate Geovisual Analytics Solutions in the Analysis of Trajectories

This paper presents an original approach for supporting the use of geovisual analytics solutions. Many models have been proposed to characterize information visualization methods, but few have been integrated to an intelligent process for supporting user in geo-information usage. Moreover, several new solutions are continuously proposed by research, but few of them are really used in operational world. For instance, the maritime surveillance systems could gain much more identification capabilities of ship behaviors with adequate geovisual analytics solutions. Therefore, we investigated the use of geovisual methods for the analysis of mobility data, such as ship trajectories. We propose a knowledge-based system using ontologies and rules. These allow modeling the domain of geovisual analytics solutions, and their capacities in the exploration and the analysis of trajectories. This system would be used to support users in geovisual analytics of movement, based on their context of use.