Digital Urban Modeling and Simulation

In the global context, the population of cities and urbanized areas has developed from a minority to become the majority. Now cities are the largest, most complex and most dynamic man-made systems. They are vibrant centres of cultural life and engines that drive local and global economies. Yet, contemporary urbanized areas are environmentally, socially and economically unsustainable entities laying increasing pressure on the surrounding rural areas. Traditional methods of planning and managing large cities that lead to this situation have reached their limits. The planning and design processes therefore need a radical re-thinking. On the computational side, this necessitates the integration of new methods and instruments. On the planning and design side, this requires the involvement of stakeholders and decision makers much earlier than normally done in the past. The combination of interactive design and computation will demonstrate the effects and side effects of urban-rural planning or re-development. We build our design research approach on dynamics and scale: viewing cities and settlements as entities with dynamic urban metabolisms, we propose to apply stocks and flows simulations to the building scale (small, S-Scale), to the urban scale (medium, M-Scale), and to the territorial scale (large, L-Scale). Our long-term goal is the sustainable urban-rural system. Planning and implementation examples from Switzerland and ETH Zurich Science City serve as test cases, with the intent to use the findings for developments in other parts of the world.

Places exercise imagination and exert power. Measuring and representing places was privileged and highly guarded in the antiquity. The rise of quantification and global mercantile traffic that ushered in the Renaissance in Europe fostered development of increasingly unambiguous and detailed representations of space and urban environments. The rise of increasingly sophisticated and precise measures at various points in time and place underpinned descriptive representations (i.e. records of how things are), concretized meanings (i.e. set forth ideals for how things could be in future), and provided instrumental prescriptions (i.e. codes to be conformed to). This chapter provides a very brief overview of selected developments in urban modeling to highlight changing roles of representations and purposes they served with a view to contextualise many lineages that inform the very notion of virtual urban modelling.

On the face of it, cities as complex systems are made of (at least) two sub-systems: a physical sub-system, made up of buildings linked by streets, roads and infrastructure; and a human sub-system made up of movement, interaction and activity. As such, cities can be thought of as socio-technical systems. Any reasonable theory of urban complexity would need to link the social and technical sub-systems to each other. Historically, most urban models have sought to make the link through the concept of distance in the physical system as a cost in the social system, defining the physical sub-system as a set of discrete zones. Such models have proved practical tools, but over the years have contributed relatively little to the development of a more general theory of the city. Here we propose a more complex and, we believe, true-to-life model based on the definition of the physical sub-system of the city as a network of spaces – streets and roads - linking buildings, rather than as a system of discrete zones. This allows us to approach urban complexity in a new way.

Two key issues – theoretically perhaps the two key issues - in the study of complexity in general are the levels problem: how organised complexity at one level becomes elementary the next level up; and the parallel problem: how systems with different internal dynamics interact with each other. In (Cohen & Stewart 1993) a general framework for conceptualising these two problems is outlined: complex phenomena at one level commonly produce lawful (though rarely mathematically describable) emergent simplicities one level up which then have their own emergent dynamic, independent of the complex processes that created them. They call such emergent simplicities, in which ‘chaos collapses’, ‘simplexities’. Simplexities of different kinds then interact and modify each other to create ‘complicities’, or complexes of simplexities, to construct the complexity of the real world. Here it is argued that this formulation captures the problem of complexity in cities as socio-technical systems, and that we need vertical theories to capture the relations across levels, and lateral theories to capture the relations of parallel systems. We outline a vertical and a lateral theory to account for generic aspects of the emergent complexity of cities.

However, both theories require an account of the linking mechanism, and here we show that since all actions that create cities are taken by human agents, the vertical and lateral linking mechanisms necessarily involve human minds, not in the sense of real historic individuals, but in the sense of a generalised individual acting according to spatial laws which are both objective and intuitively known, in the same sense that an individual who throws a ball of paper so that its parabola leads it to land in a waste paper basket intuitively ‘knows’ the law of physics. We call this generalised human subject the ‘objective subject’ of the city, and show that by virtue of being everywhere in space and time in the formation and working of the city, it everywhere imposes its point of view on it, so that cities are cognitive formations in an even more fundamental sense than they are socio- economic formations. The cognitive sets the envelope of possibility within which socio-economic processes create the city.

The evolution of integrated design and delivery processes combined with the adoption of various emerging building lifecycle information management technologies is steadily bringing measurable improvements to the industry of the built environment. Not only is this increasing the efficiency and the quality of project outcomes, but it is enabling substantial new possibilities for innovation in design and delivery. This chapter explores some of the areas of interest, the highlights and the new possibilities brought about by the adoption of these new technologies and working practices in design and construction.

Grammar formalisms for design come in a large variety, requiring different representations of the objects being generated, and different interpretative mechanisms for this generation. At the same time, all grammars share certain definitions and characteristics. Building on these commonalities, we consider a component-based approach for building grammar systems, utilizing a uniform characterization of grammars. Sortal representations constitute the components for this approach. They implement a model for representations, termed sorts, that defines formal operations on sorts and recognizes formal relationships between sorts. Each sort defines an algebra over its elements; formal compositions of sorts derive their algebraic properties from their component sorts. This algebraic framework makes sortal representations particularly suited for defining grammar formalisms considering a variety of algebra, and match relations (or interpretative mechanisms). For urban design and simulation, sortal grammars may include, among others, descriptive grammars, shape grammars, GIS-based grammars and any combination thereof.

A graph grammar for the generation of topologies for the U.S. federal courthouse typology is introduced. Possible configurations are enumerated and a nomenclature is proposed.

Achieving sustainability on an urban scale is an overwhelming problem. We can address this by dividing the problem into manageable proportions. Environmental impacts of urban design fall into measurable categories, for example, air quality, biodiversity, solid wastes, water and wastewater, hazardous materials, and impacts of nonrenewable energy use. Such measures are incorporated into building rating systems as a way of codifying sustainability. In this chapter, to illustrate such codification, we examine water use as well as generated wastewater according to the requirements of a specific sustainable building rating system. Conventional calculations are coupled with building information modeling to illustrate the overall effects of parametrically selecting fixtures, systems and materials to control the use of potable water. We further demonstrate how this approach of combining parametric building information modeling with measures of their environmental impacts can be employed on an urban scale, thereby, guiding the design of sustainable urban spaces.

Designing simulations for urban design not only requires explicit performance criteria of planning standards but a synthesis of implicit design objectives, that we will call ‘purpose rules’, with computational approaches. The former would at most lead to automation of the existing planning processes for speed and evaluation, the latter to an understanding of perceived urban qualities and their effect on the planning of cities.

In order to transform purpose rules into encoded principles we argue that the focus should not be on defining parametric constraints and quantities, but on aligning the perceptual properties of the simulations with the strategies of the stakeholders (planner/ urban designer/ architect/ developer/ community).

Using projects from the Computational Design and Research group at Aedas [CDR] as examples, this chapter will discuss how an open framework of lightweight applications with simple functionality can be integrated into the design and planning process by using computational simulations as urban design heuristics.

We present concepts and methods to cope with the enormous data needs of urban microsimulations. In the first part of the article, we adopt a process-oriented perspective on relocation, activity participation, and transportation and then refine this perspective in the microsimulation context. The second part of the article considers the parameter and state estimation problem. First, the different time scales of an urban system are identified and a rolling horizon framework for its continuous state estimation is developed. Second, the parameter estimation problem for an integrated urban microsimulation problem is investigated. The operational difficulty of jointly estimating all parameters of the urban model is met with two different approaches: the decoupling through estimated process interactions and the use of response surfaces and metamodels to mathematically approximate intractable, simulation-based processes.

The estimation of building’s energy use at the urban scale is an increasingly popular and necessary approach to minimise the primary energy use and GHG emissions. However, this activity involves the collection and management of a huge amount of data, which is often not organised in a (re)usable way by neither collectivities nor researchers. This chapter details the difficulties related to the collection of data from multiple sources, regarding incompatibilities and incompleteness in particular, and introduces the advantages of a data management using well-structured databases or GIS instead of spreadsheets or specific input files. Some research fields of interest for this matter, such as GIS, spatio-temporal databases and ontologies are introduced, and a complete approach to create a solid data management solution is proposed. The methodology described leads to a sound basis for advanced simulation and analysis of energy flow in urban zones.

We survey some recent work on interactive modeling, simulation, and control of large-scale crowds. Our primary focus is on interactive algorithms that can handle a large number of autonomous agents. This includes techniques for automatically computing collision-free trajectories for each agent as well as generating emergent crowd behaviors including lane formation, edge effects, vortices, congestion avoidance, swirling and modeling varying crowd density. Some of these methods map well to current multi-core and many-core processors and we highlight their performance in different urban scenarios.

The first use case for behavior maps is an automatic camera control technique to display interest points which represent either characteristic behavior of the crowd or novel events occurring in the scene.

As the second use case, a behavioral model to control agents’ behavior with agent-crowd interaction formulations is introduced. This model can be integrated into a crowd simulator to enhance its behavioral complexity and realism.

Urban simulation and visualization are useful to a variety of applications, including content generation for entertainment, simulation, and training, and for regional planning agencies to evaluate alternative transportation investments, land use regulations, and environmental protection policies. In this chapter, we provide a brief overview of urban simulation models, an overview of visualization strategies applied to urban models, and how recent work has built upon a synergy of urban simulation, urban visualization, and computer graphics to produce new approaches that tightly integrate previously separate areas. This last aspect exploits a form of in-situ visualization enhancing the ability of both the simulations and the visualizations. The presented collections of works represent state-of-the-art methods that will educate the reader on the latest thoughts and approaches in the field.

Cities are rapidly growing. There is an assumption that 90% of global population growth will be in cities between now and 2030. Therefore, infrastructures and the environment have to be adapted to the changing demands. Moreover, new urban development strategies have to be elaborated. In 2007, the first international Visualization Summit of more than 100 international researchers and practitioners stated a jointly developed research goal for the year 2010, namely ’Visualizing Future Cities’. Therefore in this chapter we provide an overview about visualization methods, decision support tools in architecture, urban and regional planning, stakeholder participation and collaborative environments. Also, new decision support tools for the visualization of future cities will be introduced.

Visualisation as a means of communication helps represent massive data sets, exchange knowledge and obtain better understanding of information. Spatiotemporal visualisation concerns changes of information in space and time. It has a natural advantage of revealing overall tendencies and movement patterns. Compared to traditional visual representations, it makes the notion of time accessible to non-expert users, and thus constitutes an important instrument in terms of decision-making that has been used in many application scenarios. As an interdisciplinary approach, substantial progress has been made in different domains, such as geographic information science, visualisation, or visual analytics, but there remains a lot of room for further advancements. In view of this, this paper presents a review of significant research in spatiotemporal visualisation, highlights a general workflow of data acquisition, information modelling and visualisation. Existing work from different domains are introduced, linked to the workflow, and possible integration strategies are given. Inspired by this summary, we also propose future work aiming at improving current spatiotemporal visualisation by integrating visualisation and interaction techniques more tightly.

GeoTouch was envisaged as a multi-touch display and information portal for GIS data within the Earth Observatory of Singapore: specifically as a focal point for collaborative discussion and exploration. The original GeoTouch, built in 2008 used proprietary hardware and software, and pioneered various multi-touch interface methodologies within the centre. Since then, GeoTouch-II has been unveiled, based upon commercial hardware rather than the bulky projection-based systems of the original, although the underlying GIS information handling and interfaces continue to be developed in-house. This chapter discusses both systems, drawing conclusions based upon observation and survey of more than three years of use, revealing patterns related to hardware and software limitations, and reveals important information concerning correlation between placement and usefulness.

When we visit a complex public space such as a railway station or a large shopping mall for the first time, we must rely on guide signs to find our way. In crowded situations, we are called upon to read these signs while walking so as not to disturb pedestrian flow. The present study uses an immersive visual simulation system to examine the influence of observation conditions on sign detection and recognition. The experimental variables address the spatial layout of signs as well as the presence of other pedestrians. The results indicate some quantitative relationships between the above variables and readability and suggest effective layouts for signs in spaces where crowded conditions are unavoidable.