Erwan Bocher

Noise mapping based on participative measurements

Abstract The high temporal and spatial granularities recommended by the European regulation for the purpose of environmental noise mapping leads to consider new alternatives to simulations for reaching such information. While more and more European cities deploy urban environmental observatories, the ceaseless rising number of citizens equipped with both a geographical positioning system and environmental sensors through their smartphones legitimates the design of outsourced systems that promote citizen participatory sensing. In this context, the OnoM@p system aims at offering a framework for capitalizing on crowd noise data recorded by inexperienced individuals by means of an especially designed mobile phone application. The system fully rests upon open source tools and interoperability standards defined by the Open Geospatial Consortium. Moreover, the implementation of the Spatial Data Infrastructure principle enables to break up as services the various business modules for acquiring, analysing and mapping sound levels. The proposed architecture rests on outsourced processes able to filter outlier sensors and untrustworthy data, to cross- reference geolocalised noise measurements with both geographical and statistical data in order to provide higherlevel indicators, and to map the collected and processed data based on web services.

Sensitivity of Spatial Indicators for Urban Terrain Characterization

To develop and manage urban territories and to analyze urbanisation impact on environment, an accurate knowledge of the city and its urban fabric is necessary. A physical description like building morphology or land cover/use allows some characterization of the urban terrain. A specific package for a GIS software is developed for urban analysis: UrbSAT (Urban Spatial Analysis Tool). It allows extracting knowledge from various data sources and gives some indicators to real applications (sustainable development, management policy, air quality improvement, etc). It raises issues such as database accuracy and quality, cell shape, size and orientation for the construction of spatial indicators. We present some tests to address those issues.

TAnaTo2: A Tool to Evaluate the Impact of Natural and Anthropogenic Artefacts with a TIN-Based Model

This paper presents the TAnaTo2 model. It is based on the open source GIS OrbisGIS, developed at IRSTV institute. TAnaTo2 provides new methods to evaluate the impact of natural and anthropogenic artefacts on the water runoff pathways in a peri-urban basin with a TIN-based model. It allows you to build a drainage network which represents runoff direction computed from the steepest maximum down slope. It is used to pinpoint water flow accumulation and extract watersheds. Tanato2 is applied on the Chezine basin located in north-western France, in the suburbs of Nantes. It is being used to understand the impact of urban development on the topographic course of surface waters.

A redesign of OGC Symbology Encoding standard for sharing cartography

Despite most Spatial Data Infrastructures are offering service-based visualization of geospatial data, requirements are often at a very basic level leading to poor quality of maps. This is a general observation for any geospatial architecture as soon as open standards as those of the Open Geospatial Consortium have to be applied. To improve this situation, this paper does focus on improvements at the (inter)operability side by considering standardization aspects. We propose two major redesign recommendations. First to consolidate the cartographic design knowledge at the core of the OGC Symbology Encoding standard. Secondly to build the standard in a modular way so as to be ready to host upcoming cartographic requirements. Thus, we start by defining the main portrayal interoperability use cases that frame the concept of sharing cartography. Then we bring to light the strengths and limits of the relevant open standards to consider in this context. Finally we paint a set of recommendations to overcome the limits so as to make these use cases a reality. Even if the definition of a cartographic-oriented standard is not able to act as a complete cartographic design framework by itself, we argue that pushing forward the standardization work dedicated to cartography is a way to share and disseminate good practices and finally to improve the quality of the visualizations.

Noise mapping based on participative measurements with a smartphone

Because noise is a major pollution leading to non-negligible socio-economical impacts, many national regulations aim at reducing the population noise exposure. Within the context of the European directive 2002/49/EC, a special attention is paid to the evaluation of the existing noise environment. Nowadays, this assessment is addressed based on simulated noise maps, which however present some limitations due to the simplification of noise generation and propagation phenomena. Smartphone participative measurements are alternatively being developed, offering the high temporal and spatial granularities recommended by the EU directive. However, the existing approaches often lack a quantification of the produced noise maps accuracy, and are rarely user-oriented. In this context, within the framework of the EU project ENERGIC-OD, a Spatial Data Infrastructure (SDI “OnoMap”) has been developed to manage smartphones measurements using a dedicated Android application (“NoiseCapture”) and to produce relevant noise m...

Integrated method for cities air temperature estimation

Urban Heat Island (UHI) is defined as the air temperature difference between the city and its surrounding areas. This phenomenon varies spatially (depending on the type of urban fabric constituting each neighborhood) and temporally (depending on the time of the day, on the season and on the weather conditions). This contribution proposes a methodology to model the UHI spatially and temporally using simple models built with free and open sources softwares (orbisGIS and python language). Ten air temperature sensors have been implemented in several neighborhoods of the Nantes urban area (a west coast french conurbation). The difference of UHI is observed and modeled for each of those sites. Spatial differences are modeled according to geographical indicators characterizing the urban surroundings of each temperature station. Temporal variations are modeled according to weather conditions (such as wind speed, solar radiations, etc.) for different time scales : diurnal and nocturnal differences, daily variations and seasonal variations. The objective is to create a method which may be applied for any city in France. Geographical indicators are then calculated with OrbisGIS software from geographical data which are homogeneous and available at the french territory scale. Wheather conditions are recorded by MeteoFrance stations, which follow the same standard for the measurement of climatic parameters all around France. Climatic data analysis and modeling are performed with Python language using libraries such as Pandas and StatsModels. Modeled established according to the Nantes temperature dataset are verificated according to new air temperature networks implemented in the city of Nantes as well as other cities of west France (Angers, La Roche-sur-Yon).

A combined approach to detect urban features from multi-spectral and radardata

With increase of urban population, the cities have an impact more and more important on environment. Because of artificial surface, building morphology, economical activities, traffic several natural ecosystem are modified. To analyze this impact, the land covers/land uses have to be identified exactly in an urban area. To reach this objective, remote sensing represents an important and complete source of information. Joint use of radar and optical data allows improving results of classical classification to identify the cover mode. Re-sampled to 1m resolution, the difference between the two classifications is analyzed to detect the confusion in each class corresponding to a land cover/land use. Finally, a vector process allowed to transform the geometry of the results: a polygon aggregates several pixels. Combination of results is also possible with GIS functionalities like contains, intersect, cut, and permits to propose aland cover/ land use description on the study area.