François Golay

Solar Radiation over the Urban Texture: LIDAR Data and Image Processing Techniques for Environmental Analysis at City Scale

Keynotes.- A Virtual Geographic Environment for a Simulation of Air Pollution Dispersion in the Pearl River Delta (PRD) Region.- Representing and Exchanging 3D City Models with CityGML.- Research and Development Program for the Third National Geographic Information System Project in Korea: Korean Land Spatialization Program.- Papers.- Construction Operators for Modelling 3D Objects and Dual Navigation Structures.- A Multilayered Space-Event Model for Navigation in Indoor Spaces.- Towards Defining a Framework for Automatic Generation of Buildings in CityGML Using Building Information Models.- Managed Objects for Infrastructure Data.- Integrating Terrain Surface and Street Network for 3D Routing.- Using a B-Rep Structure to Query 9-Intersection Topological Relationships in 3D GIS - Reviewing the Approach and Improving Performance.- Query Processing in 3D Spatial Databases: Experiences with Oracle Spatial 11g.- Making Interoperability Persistent: A 3D Geo Database Based on CityGML.- Use of Finite Arithmetic in 3D Spatial Databases.- Automatic Digital Aerial Image Resection Controlled by LIDAR Data.- Automatic Surface Patch Generation from a Video Image Sequence.- Indoor 3D Modeling and Visualization with a 3D Terrestrial Laser Scanner.- Automatic Image Mosaic-Building Algorithm for Generating Facade Textures.- 3D Continuous K-NN Query for a Landmark-based Wayfinding Location-based Service.- 3D Geo-Network for Agent-based Building Evacuation Simulation.- Hierarchical Modelling of Multi-Geospatial Databases as Basis for Geo-Oriented 3D Analysis Capabilities.- Solar Radiation over the Urban Texture: LIDAR Data and Image Processing Techniques for Environmental Analysis at City Scale.- Creation and Error Analysis of High Resolution DEM Based on Source Data Sets of Various Accuracy.- A Topological Analysis Method for 3D Geo-Entities Structured as Hexahedron Tessellations.- Constraint-based Generation and Visualization of 3D City Models.- GeoVEs as Tools to Communicate in Urban Projects: Requirements for Functionality and Visualization.- Producing 3D Applications for Urban Planning by Integrating 3D Scanned Building Data with Geo-spatial Data.- 3D Dynamic Simulation and Visualization for GIS-based Infiltration Excess Overland Flow Modelling.A complete methodology from the extraction of Light Detection and Ranging (LIDAR) data to the environmental analysis of urban models and the visualization of results is presented. Aim of t he work is to establish a process to investigate digital urban models integra ting cross-disciplinary competences, like remote sensing, GIS, image proces sing and urban and environmental studies. Toward this goal, working on several interfaces, tools and datasets was necessary to provide a conse quent structure to the introduced methodology. Case study for application was a squared area 300 m etres wide in central Geneva where LIDAR data are available. The us of a hybrid approach from raw LIDAR data and vectorial digital maps (GIS data) of buildings footprints for the interpolation of a 2.5 -D urban surface model, with a resolution grid of 0.50 by 0.50 metres, allo wed to refine vertical

Digital Urban Morphometrics: Automatic Extraction and Assessment of Morphological Properties of Buildings

The aim of this article is to present a method to calculate the morphological properties of the built environment using LiDAR (light-detection and ranging) data, geographic information systems (GIS) data and three-dimensional (3D) models of cities as a source of information. A hybrid approach that takes into account different types of inputs and consequently evaluates the accuracy of each type of used data is presented. This work is intended to give a first response to the lack of comprehensive and accurate procedure that uses LiDAR data in order to automatically derive precise morphological properties, such as volumes and surfaces (facades and roofs) of buildings. The method was tested on two case-study areas in the Geneva region with different characteristics, one in the old town along the Rhone River and the other on the CERN campus. A statistical analysis that compares the results of the computation with the 3D model of the built environment was used to validate the results, complemented by significance statistical tests. Outcomes showed that the proposed method to derive morphological properties can reach high levels of accuracy, thus enhancing the potential uses of LiDAR data for numerous applications, typically for the assessment of the urban environmental quality (UEQ) at the city and district scale, such as the estimation of the potential deployment of renewable energies in the built environment and the determination and monitoring of several urban indicators.

GIS and LIDAR Data Analysis for the Integration of Multidimensional Indicators on Urban Morphogenesis Multi-agent Vector Based Geosimulation

In this paper we present an application of GIS and Airborne Light Detection and Ranging (LIDAR) data analysis for computation of buildings visibility, solar exposition and extraction of morphological indicators in the context of urban group analysis and morphogenesis geosimulation. The interdisciplinary project between geomaticians and architects aims to provide a simulation model based upon dynamic computation of building agents’ satisfaction degree, incorporating analysis results using a hybrid approach derived from GIS and raw LIDAR data.

Understanding Collaborative Use of GIS through Social Cognition

Land management activities become more and more complex and involved. Decision making is a social activity, involving numerous people, with different backgrounds and different beliefs. This paper explores potential contributions of social cognition science that may improve human-computer interaction, and more generally GIS usability through better use patterns and design methods. It concludes with the need to foster the role of GIS and maps as media for better human-human interaction.

Preliminary insights on continuity and evolution of concepts for the development of an urban morphological process ontology

Reference LASIG-CHAPTER-2007-002View record in Web of Science Record created on 2007-10-04, modified on 2016-08-08

Screening differences between a local inventory and the Emissions Database for Global Atmospheric Research (EDGAR)

In the vast majority of Latin American and South American countries, global emission inventories (EIs) are often used for modelling air quality. In particular the Emission Database for Global Atmospheric Research EDGAR is widely deployed but several studies have pointed to some gaps in comparison with national/regional inventories which incur errors in interpreting results. In Cuba, due to scarcity of a spatially distributed national inventory, EDGAR has been used as entry for air quality modelling without verifying their reliability over the region. Our goal in this article is to compare and contrast EDGAR with a local inventory and to evaluate similarities or discrepancies. We use advanced comparison techniques developed by the Forum for Air Quality Modelling in Europe-FAIRMODE. This approach differs from others in the detailed way in which it points out the differences and gets insights in possible explanations. Overall, EDGAR provided spatially smoother results and relatively lower values in hotspot areas. Coarse differences in terms of activities were low for all analyzed sectors. However, EDGAR overestimates emission factors (EFs) of stationary sources for CO by a factor of 3 and SO2 by a factor of 1.5 while underestimates those of PPM10 by a factor of 25. Most of the road transport EFs are overestimated in EDGAR; PM10, CO and NOx are 2 times higher, while CH4 and SO2 are 5 to 20 times higher. Large differences were found on the spatial distribution of energy and industrial sources. EDGAR can be regionally accepted as a reference but it is not recommended for air quality simulation over Cuba. A more complete reporting must be expected when more official national data are due. A review and evaluation of local emission inventories over Cuba can be useful for identifying potential areas for future improvement.

Pose estimation of landscape images using DEM and orthophotos

In this paper, we propose a methodology for the estimation of the pose of oblique landscape images. Knowledge about the pose is needed for using such images in augmented reality applications or to allow projection of pixels in a GIS for spatial analysis. We propose to estimate the pose using a 30 digital elevation model (OEM) rendered with an ortho-image as reference. Starting from a rough estimation, the pose is refined by exploiting correspondences detected with a local normalized cross-correlation method. Matches are searched between edge features extracted both in the query image and in a synthetic image generated from the DEM and the ortho-image. A RANSAC approach based on the camera model extracts the best matches. Few iterations of the algorithm provide a precise estimation of the pose, leading to a precise georeferencing of the query image. We tested the proposed methodology to images of a popular glacier in the south of Switzerland downloaded from Panoramio.

Remote-evaluation of user interaction with WebGIS

In this paper we propose a framework that characterizes user interaction with webGIS. Furthermore we present a technique to remotely test and evaluate such systems. Our framework does not only include parameters describing the usability of a system, but refers to factors that we argue influence interaction and satisfaction substantially, such as the users background and previous experience, or the users computer equipment. We have developed tools and techniques to test webGIS remotely so that users can evaluate the system in their own environment rather than an intrusive laboratory. This remote-testing environment allows us to record parameters such as task completion time, the rate of interactions but also the type of operating system and network connection used during the evaluation. In a case study we captured the interaction of more than 300 users with a system whose purpose was to locate points of interest in a region of Switzerland. The data that was gathered during this remote-evaluation was used to validate and verify the conceptual framework. We have found out that parameters such as the users experience with similar systems or the type of input device and connection speed significantly influence both the interaction and the users satisfaction. The tools and the framework that we present in this paper are useful for developers and designers of webGIS, but also for researchers who are interested in evaluating the usability of such systems.

User Performance in Interaction with Web-GIS: A Semi-Automated Methodology Using Log-Files and Streaming-Tools

This paper describes a framework of methods for the measurement and evaluation of users’ performance in interaction with a web-GIS. The framework involves testing of a system with real-world users, streaming of the user’s screen during the evaluation and the analysis of web-server log files after the evaluation. We have developed and tested this method within a project called RIV together with real-world users that are using a web-GIS. We found out that users have different strategies when interacting with a web-GIS that offers different manners of interaction. The findings that we present in this paper are useful for developers and designers of web-GIS and can help improving such systems.

Shifts in wind energy potential following land-use driven vegetation dynamics in complex terrain

Many mountainous regions with high wind energy potential are characterized by multi-scale variabilities of vegetation in both spatial and time dimensions, which strongly affect the spatial distribution of wind resource and its time evolution. To this end, we developed a coupled interdisciplinary modeling framework capable of assessing the shifts in wind energy potential following land-use driven vegetation dynamics in complex mountain terrain. It was applied to a case study area in the Romanian Carpathians. The results show that the overall shifts in wind energy potential following the changes of vegetation pattern due to different land-use policies can be dramatic. This suggests that the planning of wind energy project should be integrated with the land-use planning at a specific site to ensure that the expected energy production of the planned wind farm can be reached over its entire lifetime. Moreover, the changes in the spatial distribution of wind and turbulence under different scenarios of land-use are complex, and they must be taken into account in the micro-siting of wind turbines to maximize wind energy production and minimize fatigue loads (and associated maintenance costs). The proposed new modeling framework offers, for the first time, a powerful tool for assessing long-term variability in local wind energy potential that emerges from land-use change driven vegetation dynamics over complex terrain. Following a previously unexplored pathway of cause-effect relationships, it demonstrates a new linkage of agro- and forest policies in landscape development with an ultimate trade-off between renewable energy production and biodiversity targets. Moreover, it can be extended to study the potential effects of micro-climatic changes associated with wind farms on vegetation development (growth and patterning), which could in turn have a long-term feedback effect on wind resource distribution in mountainous regions.