Extraction of Urban Environmental Quality Indicators using LiDAR-Based Digital Surface Models

The visualization of specific 3-D urban scenes can be done calling upon different techniques, from those more traditional, such as photogrammetry, to the most advanced ones, such as laser scanning that uses different techniques and algorithms of selection and modelling of 3-D point clouds. The use and utility of this kind of data for the study of urban development remain however debatable. Indeed, indicators for urban development and durability are highly necessary and the best methodology to build them is largely open. This thesis anticipates the use of 2-D and 3-D models and data for the environmental analysis of cities, aiming to provide useful tools for urban planning and design. According to end-users requirements, the extraction of urban environmental quality (UEQ) indicators from 2-D and 3-D information using innovative methods is proposed and implemented, which is based on recent research on computational algorithms for the analysis, evaluation, management and design of the urban space. Moreover, results that can be obtained with different data sources and aggregation methods are compared. In particular, the main advantages of urban models generated from LiDAR data are highlighted. In consequence, an iterative process is proposed, involving professionals of various fields, aiming at improving the utility of those indicators for the support of applied decision activities related to the sustainable development of cities. This process is sub-divided in three correlated steps: A preliminary inquiry concerning the user requirements for the implementation of a 3-D project of the State/City of Geneva was launched. Based on the obtained replies, several potential applications related to both the definition and extraction of urban indicators were identified, and also, end-users were classified into 6 different domains: 1– architecture, urbanism and territory planning; 2– urban traffic (motor vehicles, trains and airplanes); 3– environment and energy; 4– pedestrian and cyclist mobility; 5– security and emergency situations management; 6– underground information; Based on point 1. and according to the assessment of the specific needs among each of these domains, several interviews were carried out in which 25 end-users decided to focus on UEQ indicators considering three main stakes: 1– assessment of the morphological properties of the urban texture; 2– exploration of the solar potential on the urban fabric; 3– estimation of the energy demand on the urban fabric. Many empirical case-studies are emphasized, mostly for the city of Geneva, and also for the cities of Lausanne and Florence. These indicators are extracted from the segmentation of planar roof areas using classified LiDAR point clouds and the use of image processing techniques based on Digital Elevation Models (DEM) and Digital Height Models (DHM), defined in this thesis as 2.5-Digital Urban Surface Models (2.5-DUSM) and normalized 2.5-Digital Urban Surface Models (n2.5-DUSM) respectively. These models are constructed in a step by step basis, using LiDAR and 2-D and 3-D vector data, thus applying different methods of interpolation and enhancement, whose accuracy is also evaluated on a statistical basis; Finally, an inquiry on how the same group of 25 end-users mentioned in point 1. perceives and interprets the different exploratory 2-D and 3-D geo-visualizations proposed for some of the UEQ indicators is undertaken, evaluating their utility according to the requirements previously defined.

Sustainable Development, Planning and Poverty Alleviation

Jean-Claude Bolay, Eléonore Labattut

In 2018, the world population is around 7.6 billion, 4.2 billion in urban settlements and 3.4 billion in rural areas. Of this total, according to UN-Habitat, 3.2 billion of urban inhabitants live in southern countries. Of them, one billion, or nearly a third, live in slums. Urban poverty is therefore an endemic problem that has not been solved despite all initiatives taken to date by public and private sectors. This global transformation of our contemporary societies is particularly challenging in Asia and Africa, knowing that on these two continents, less than half of the population currently lives in urban areas. In addition, over the next decades, 90% of the urbanization process will take place in these major regions of the world. Urban planning is not an end in itself. It is a way, human and technological, to foresee the future and to act in a consistent and responsible way in order to guarantee the well-being of the populations residing in cities or in their peripheries. Many writers and urban actors in the South have criticized the inadequacy of urban planning to the problems faced by the cities confronting spatial and demographic growth. For many of them the reproduction of Western models of planning is ineffective when the urban context responds to very different logics. It is therefore a question of reinventing urban planning on different bases. And in order to address the real problems that urban inhabitants and authorities are facing, and offering infrastructures and access to services for all, this with the prospect of reducing poverty, to develop a more inclusive city, with a more efficient organization, in order to make it sustainable, both environmental than social and economic. The field work carried out during recent years in small and medium-sized cities in Burkina Faso, Brazil, Argentina and Vietnam allows us to focus the attention of specialists and decision makers on intermediate cities that have been little studied but which are home to half of the world's urban population. From local diagnoses, we come to a first conclusion. Many small and medium-sized cities in the South can be considered as poor cities, from four criteria. They have a relatively large percentage of the population is considered to be poor; the local government and its administration do not have enough money to invest in solving the problems they face; these same authorities lack the human resources to initiate and manage an efficient planning process; urban governance remains little open to democratic participation and poorly integrates social demand into its development plans. Based on this analysis, we consider it is imperative to renovate urban planning as part of a more participatory process that meets the expectations of citizens with more realistic criteria. This process incorporates different stages: an analysis grounded on the identification of urban investment needed to improve the city; the consideration of the social demands; a realistic assessment of the financial resources to be mobilized (municipal budget, taxes, public and international external grants, public private partnership); a continuous dialogue between urban actors to determine the urban priorities to be addressed in the coming years. This protocol serves as a basis for comparative studies between cities in the South and a training program initiated in Argentina for urban actors in small and medium-sized cities, which we wish to extend later to other countries of the South.

2019

The analysis of digital urban models derived from Lidar data for the assessment of the environmental quality of cities

Gilles Desthieux, Claudio Magalhaes Carneiro

Aim of the work is to assess the environmental quality and the potential implementation of renewable energies at the scale of the city referring to Light Detection and Ranging (LIDAR) data. This source of data allows to predict environmental indicators in a fast way with no need to refer to the construction of complex models of the urban layout / geometry. A complete methodology from the extraction of LIDAR data and large database alphanumerical information of buildings typology, that define the assumptions of our model, to the environmental analysis of urban models and the visualization of results is presented. The methodology investigates digital urban models by integrating cross-disciplinary competences, like remote sensing, GIS, database management, image processing and urban and environmental studies. A special focus will be given to the following research axes: - Applying the Light and Thermal (LT) Model, estimation of energy consumption for heating and lighting; - Interpreting energy results and solar potential: comparisons, scenarios and estimation of energy production through renewable energy (sun); - Guidelines for potential of installation of solar panels (PV and thermic) on campus; - Guidelines for renovation (localized intervention where needed); - Guidelines for the infiling with new buildings on the Campus without compromising solar admittance; - Analysis of the influence of trees on the solar admittance on campus. Case study for application is a rectangular area of 1100 meters by 650 meters of the Swiss side (Site of Meyrin) of the international organization CERN, located in Geneva, Switzerland, where all data needed to analyze the urban fabric in a very innovative way are available.

2009

Assessing the contribution of Circular Economy to Urban Sustainability: an analysis based on the use of indicators

Ivo Philippe Baur, Claudia Rebeca Binder Signer, Valeria Superti

Currently our world is becoming increasingly urban, with around 50% of its population living in cities. Whereas cities produce 80% of the worldwide GDP and are places with high innovation, they also consume 75% of worldwide resources and produce 80% of CO2 emissions. Thus, achieving urban sustainability will be crucial in the future. To reduce resource consumption in cities, Circular Economy has been proposed as a key concept, i.e. using resources more efficiently through value retention processes and minimizing the waste produced. Although the concept of the Circular Economy is not new, its potential contribution to Urban Sustainability still needs to be elicited. How does the Circular Economy conceptually integrate and, contribute to, Urban Sustainability? To answer this question, we focused on how the transitions towards the Circular Economy and towards Urban Sustainability are currently assessed. We conducted a cluster analysis of approximately 50 sets of indicators. Roughly half of the sets are currently used by municipalities or institutions to track the progress of cities towards the Circular Economy; the others cover Urban Sustainability. Each set contains approximately 40 indicators, although the number varies greatly. From each set, we extracted single indicators and categorized them according to conceptual frameworks, namely the three pillars of sustainability and the Sustainable Development Goals. We analyzed the overlap between the sets to derive clusters. We hypothesized that it should be possible to detect two clusters of sets of indicators: one referring to Circular Economy, one to Urban Sustainability. This would emphasize the differences in how the transitions towards Circular Economy and Urban Sustainability have been assessed, through the choice of distinct indicators. Our results will have both theoretical and practical contributions, informing the debate on the differences and overlaps between the two concepts and supporting urban communities in developing ad-hoc sets of indicators.

2019

Assessing the contribution of Circular Economy to Urban Sustainability: an analysis based on the use of indicators

Ivo Philippe Baur, Claudia Rebeca Binder Signer, Valeria Superti

2019

Sustainable Development, Planning and Poverty Alleviation

Jean-Claude Bolay, Eléonore Labattut

2019