Procedural city layout generation based on urban land use models

2010

We report about our student project with the objective of a procedural generation of pseudo-random cities, streets and terrains. The focus of the project is primarily the procedural modelling, real-time rendering and modelling on demand at run-time. This paper discusses the generation of terrain, road network, different approaches to build houses like random methods or shape grammars, and additional graphical effects. The framework is designed in away that a user without any previous knowledge is able to create infinite worlds on the fly as easy and interactively as possible while still having a wide influence on the appearance.

Proceedings of GDTW 2007: The Fifth Annual International Conference in Computer Game Design and Technology

Contemporary 3D games are often situated within large urban environments. This necessitates a time-consuming and expensive content creation process involving the modelling of vast amounts of geometric detail: including terrain, roads, buildings, and other associated features. We present a system called Citygen that aims to automate as much of this as possible by employing procedural generation methods to rapidly create the urban geometry typical of a modern city. Procedural methods have long been used within the graphics and game development communities to generate natural phenomena such as plants and trees. We employ these methods to generate the underlying road networks that form the structure of cities and urban neighbourhoods. These road networks are automatically mapped to any supplied terrain model, and adapt themselves to the specific geometry of the underlying terrain. Building footprints are automatically extracted from the resulting model and buildings can then be inserted either procedurally or by hand. Our system is unique in that it is designed to allow developers hands-on interactive control over the generation process. We achieve this by providing an interface allowing the user to directly manipulate geometric elements such as road intersection nodes, and to directly control and specify many aspects of the procedural generation. The results are updated in real time, thus facilitating an interactive design process.

2004

Cities are the largest human artifacts and appear often in digital entertainment. Building digital models of them is extremely difficult, yet there are few tools that can assist artists in this task. We describe a method for procedurally generating city models using agentbased modeling, an established simulation technique in the social, biological, and physical sciences. Our system accepts a terrain description as input and produces a land usage map that portrays roads and residential, commercial, and industrial land use. The results conform well to modern patterns of land use, but each generated city is unique. Our system is controlled by a set of parameters that users can alter numerically or gesturally in order to constrain and guide the results to fit a particular application’s needs.

Proceedings of eCAADe, 2007

This paper presents a novel approach for the automatic creation of vegetation scenarios in real or virtual 3D cities in order to simplify the complex design process and time consuming modeling tasks in urban landscape planning. We introduce shape grammars as a practical tool for the rule-based generation of urban open spaces. The automatically generated designs can be used for pre-visualization, master planning, guided design variation and digital content creation in general (e.g. for the entertainment industry). In a first step, we extend the CGA shape grammar by Müller et al. (2006) with urban planning operations. In a second step, we employ the possibilities of shape grammars to encode design patterns (Alexander et al., 1977). Therefore, we propose several examples of design patterns allowing for an intuitive high-level placement of objects common in urban open spaces (e.g. plants). Furthermore, arbitrary interactions between distinct instances of the vegetation and the urban environment can be encoded. With the resulting system, the designer can efficiently vegetate landscape and city parks, alleys, gardens, patios and even single buildings by applying the corresponding shape grammar rules. Our results demonstrate the procedural design process on two practical example scenarios, each one covering a different scale and different contexts of planning. The first example illustrates a derivation of the Garden of Versailles and the second example describes the usage of high-level rule sets to generate a suburbia model.

Computer Graphics Forum, 2011

In this paper, we present new solutions for the interactive modeling of city layouts that combine the power of procedural modeling with the flexibility of manual modeling. Procedural modeling enables us to quickly generate large city layouts, while manual modeling allows us to hand-craft every aspect of a city. We introduce transformation and merging operators for both topology preserving and topology changing transformations based on graph cuts. In combination with a layering system, this allows intuitive manipulation of urban layouts using operations such as drag and drop, translation, rotation etc. In contrast to previous work, these operations always generate valid, i.e., intersection-free layouts. Furthermore, we introduce anchored assignments to make sure that modifications are persistent even if the whole urban layout is regenerated.

Computer Graphics Forum, 2012

: Procedural Parcel Generation. Our method creates parcels inside city blocks (f,i) using two different subdivision techniques -skeleton (g, shaded part of f) or OBB (h, unshaded part of f). The subdivision attributes are automatically extracted from observed real-world cities (a,b,c) or determined by the user. The resulting parcel configurations closely resemble real-world subdivisions, as shown by our statistical and visual comparison of procedural and observed parcel datasets (d,e).

Abstract. The creation of virtual urban environments, corresponding to realworld settings, has become a very frequent subject of content development for Virtual Reality Systems, serving multiple activities such as urban planning, virtual tourism and education, among others. Their extensive and complex nature, however, makes their conception very expensive and time-consuming, which has led many researchers for the look of semi-automatic methods for their creation.

The common trend in the scientific inquiry of urban areas and their populations is to use real-world geographic and population data to understand, explain, and predict urban phenomena. We argue that this trend limits our understanding of urban areas as dealing with arbitrarily collected geographic data requires technical expertise to process; moreover, population data is often aggregated, sparsified, or anonymized for privacy reasons. We believe synthetic urban areas generated via procedural city generation, which is a technique mostly used in the gaming area, could help improve the state-of-the-art in many disciplines which study urban areas. In this paper, we describe a selection of research areas that could benefit from such synthetic urban data and show that the current research in procedurally generated cities needs to address specific issues (e.g., plausibility) to sufficiently capture real-world cities and thus take such data beyond gaming.

Journal For Virtual Worlds Research

The creation of virtual environments, corresponding to real world settings, constitutes one of the most important, but also most time and resource demanding processes in content development for virtual worlds. By querying real-world data sources, the building process can be automated, reducing the need for human intervention. However, these may present additional management difficulties due to their number, dimension, format or level of detail, therefore requiring specific techniques to operate on them. This paper describes the application of a procedural modeling solution, called PG3D System, on the creation of realistic virtual urban environments and their employ in virtual world applications. This system's implementation in spatial database management systems induces fast data access, large data manipulation features, complex query capabilities and format flexibility, allowing the fast creation of large scale virtual environments, imbued with optimized data structures, compat...

Cities are popular settings for computer game levels and flight simulators. The creation of a virtual city model poses a distinct set of challenges to the designers. The design of a virtual city often starts with the creation of a road network. The road network subdivides the virtual space into smaller areas that are surrounded by streets. These areas can be further subdivided to create areas for buildings, parklands etc. We present a procedural approach to generate urban street networks for virtual cities in real-time on desktop computers with graphic accelerators. A street grid layout for the viewing area is generated based on local information and a small set of parameters. As users travel through the world the street grid is incrementally extended as needed. From the street grid, road geometry and lot shapes can be generated. The lot shapes can be used in a subsequent step to generate the content of the lot such as buildings. This approach facilitates the generation of extremely large cities consisting of lot shapes varying in size and shape.