A GIS toolset for automated partitioning of urban lands

Urban growth models operating at finer spatial scale usually incorporate a subdivision module that carries out automated partitioning of the lands selected for future development. In this paper, we describe the development and implementation of Parcel-Divider – a GIS toolset for automated subdivision of land parcels. In addition to automating the process of generating urban layouts such as city blocks, streets and cadastral lots, the toolset is capable of extending roads to new subdivisions. Researchers can integrate the toolset into their modeling while planners can use it as a standalone application to visualize scenarios of infrastructure arrangements in growing areas of the city. Our tool-generated subdivision configurations closely match the subdivision styles observed in real-world cities when compared visually as well as statistically.     

Interactive Modeling of City Layouts using Layers of Procedural Content

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.     

Symmetrization of facade layouts

We present an automatic approach for symmetrizing urban facade layouts. Our method can generate a symmetric layout through minimally modifying the original input layout. Based on the principles of symmetry in urban design, we formulate facade layout symmetrization as an optimization problem. Our method further enhances the regularity of the final layout by redistributing and aligning elements in the layout. We demonstrate that the proposed solution can effectively generate symmetric facade layouts.     

Game level layout from design specification

The design of video game environments, or levels, aims to control gameplay by steering the player through a sequence of designer‐controlled steps, while simultaneously providing a visually engaging experience. Traditionally these levels are painstakingly designed by hand, often from pre‐existing building blocks, or space templates. In this paper, we propose an algorithmic approach for automatically laying out game levels from user‐specified blocks. Our method allows designers to retain control of the gameplay flow via user‐specified level connectivity graphs, while relieving them from the tedious task of manually assembling the building blocks into a valid, plausible layout. Our method produces sequences of diverse layouts for the same input connectivity, allowing for repeated replay of a given level within a visually different, new environment. We support complex graph connectivities and various building block shapes, and are able to compute complex layouts in seconds. The two key components of our algorithm are the use of configuration spaces defining feasible relative positions of building blocks within a layout and a graph‐decomposition based layout strategy that leverages graph connectivity to speed up convergence and avoid local minima. Together these two tools quickly steer the solution toward feasible layouts. We demonstrate our method on a variety of real‐life inputs, and generate appealing layouts conforming to user specifications.     

Space, colour and typography on visual display terminals

Some guidelines are given to meet the observed need for rules about layout, the use of colour and typography on display screens so as to create texts with optimal legibility. Examples of videotex pages are used to illustrate right and wrong layouts, applications of colour and of letter type. The guidelines can be generalized to other types of display such as those used in personal computers and, to a more limited extent, to the use of graphics instead of text. Finally, figures are given on the general public's subjective appreciation of some alternative display layouts.     

Modelling the Appearance and Behaviour of Urban Spaces

Urban spaces consist of a complex collection of buildings, parcels, blocks and neighbourhoods interconnected by streets. Accurately modelling both the appearance and the behaviour of dense urban spaces is a significant challenge. The recent surge in urban data and its availability via the Internet has fomented a significant amount of research in computer graphics and in a number of applications in urban planning, emergency management and visualization. In this paper, we seek to provide an overview of methods spanning computer graphics and related fields involved in this goal. Our paper reports the most prominent methods in urban modelling and rendering, urban visualization and urban simulation models. A reader will be well versed in the key problems and current solution methods.     

Mesh layouts for block-based caches

Current computer architectures employ caching to improve the performance of a wide variety of applications. One of the main characteristics of such cache schemes is the use of block fetching whenever an uncached data element is accessed. To maximize the benefit of the block fetching mechanism, we present novel cache-aware and cache-oblivious layouts of surface and volume meshes that improve the performance of interactive visualization and geometric processing algorithms. Based on a general I/O model, we derive new cache-aware and cache-oblivious metrics that have high correlations with the number of cache misses when accessing a mesh. In addition to guiding the layout process, our metrics can be used to quantify the quality of a layout, e.g. for comparing different layouts of the same mesh and for determining whether a given layout is amenable to significant improvement. We show that layouts of unstructured meshes optimized for our metrics result in improvements over conventional layouts in the performance of visualization applications such as isosurface extraction and view-dependent rendering. Moreover, we improve upon recent cache-oblivious mesh layouts in terms of performance, applicability, and accuracy.     

Uncluttering Graph Layouts Using Anisotropic Diffusion and Mass Transport

Many graph layouts include very dense areas, making the layout difficult to understand. In this paper, we propose a technique for modifying an existing layout in order to reduce the clutter in dense areas. A physically inspired evolution process based on a modified heat equation is used to create an improved layout density image, making better use of available screen space. Using results from optimal mass transport problems, a warp to the improved density image is computed. The graph nodes are displaced according to the warp. The warp maintains the overall structure of the graph, thus limiting disturbances to the mental map, while reducing the clutter in dense areas of the layout. The complexity of the algorithm depends mainly on the resolution of the image visualizing the graph and is linear in the size of the graph. This allows scaling the computation according to required running times. It is demonstrated how the algorithm can be significantly accelerated using a graphics processing unit (GPU), resulting in the ability to handle large graphs in a matter of seconds. Results on several layout algorithms and applications are demonstrated.     

Interactive microcomputer graphic methods for smoothing craft layouts

Computer-aided layout planning has been under development since the early 1960s, and many layout programs are based on the powerful and well known program, CRAFT (Computerized Relative Allocation of Facilities Technique by Armour and Buffa 1963).

Unfortunately, the major drawback of these facilities layout programs is that they often create unrealistic and impractical designs since the resulting block layouts can have odd shapes. Most architectural building designs require that the rooms and departments be in the form of squares, rectangles or L-shapes. The traditional approach to rectifying this problem is to manually modify the block plans at the corresponding expense of time and effort.

This paper identifies the problems and proposes interactive graphic methods for smoothing CRAFT layouts. In addition, a new method for the assessment of layout efficiency is introduced to measure the quality of a layout before and after smoothing.     

VisualTPL: A visual dataflow language for report data transformation

Data transformation, an important part of report generation, converts the layout of source data into a new layout suitable for presentation. Many report tools have been developed for end-users to specify data transformation. However, current report tools only support a limited set of report layouts. This paper proposes a visual dataflow programming language, called VisualTPL, to resolve this problem. Data transformation is accomplished by writing graphical dataflow programs, which manipulate tables as first-class objects with a set of extendable table operations. A report tool, called VisualTPS, has been developed to offer an easy and intuitive end-user programming environment. Reports with sophisticated layouts can be created through top-down decomposition and incremental development. An evaluation has been conducted to assess end-users' performance with VisualTPL. The results indicated that end-users could learn VisualTPL in a short time and create complicated report layouts all by themselves. And, in comparison with a commercial report tool, VisualTPL offered end-users similar performances and was preferred over the commercial tool.     

Papilio: Visualizing Android Application Permissions

We introduce Papilio, a new visualization technique for visualizing permissions of real‐world Android applications. We explore the development of layouts that exploit the directed acyclic nature of Android application permission data to develop a new explicit layout technique that incorporates aspects of set membership, node‐link diagrams and matrix layouts. By grouping applications based on sets of requested permissions, a structure can be formed with partially ordered relations. The Papilio layout shows sets of applications centrally, the relations among applications on one side and application permissions, as the reason behind the existence of the partial order, on the other side. Using Papilio to explore a set of Android applications as a case study has led to new security findings regarding permission usage by Android applications.     

A shape-based block layout approach to facility layout problems using hybrid genetic algorithm

In this paper, a shape-based block layout (SBL) approach for solving facility layout problem with unequal-areas and fixed-shapes is presented. The SBL approach employs hybrid genetic algorithm to find good solution. The existing algorithms for the problem of assigning positions to unequal-area and fixed or approximated shape departments within a given building area can produce solutions with some drawbacks, which require extensive manual revision to create practical layouts and produce irregular building shapes and too much unusable spaces. The objective function of SBL approach minimizes total material handling cost and maximizes space utilization. Experimental results show that the SBL approach is able to improve solution and it can create more practical layout than that of existing approaches.     

Customizing a Fisheye View Algorithm to Preserve the Mental Map

Frequently, large knowledge bases are represented by graphs. Many visualization tools allow users or other applications to interact with and adjust the layouts of these graphs. One layout adjustment problem is that of showing more detail without eliding parts of the graph. Approaches based on a fisheye lens paradigm seem well suited to this task. However, many of these techniques are non-trivial to implement and their distortion techniques often cannot be altered to suit different graph layouts. When distorting a graph layout, it is often desirable to preserve various properties of the original graph in an adjusted view. Pertinent properties may include straightness of lines, graph topology, orthogonalities and proximities. However, it is normally not possible to preserve all of the original properties of the graph layout. The type of layout and its application should be considered when deciding which properties to preserve or distort. This paper describes a fisheye view algorithm which can be customized to suit various different graph layouts. In contrast to other methods, the user can select which properties of the original graph layout to preserve in an adjusted view. The technique is demonstrated through its application to visualizing structures in large software systems.     

A Geometrical Analysis of the Layout of Acaya, Italy

The analysis of the urban fabric contained within the city walls of the town of Acaya, made possible by a new integrated survey involving manual, topographical, photogrammetric and 3D laserscan techniques, has cast doubts on the conventional attribution of the city layout to Gian Giacomo dell??Acaya. A rectangular layout consisting of six blocks divided by six longitudinal streets and three lateral streets is indicative of a medieval date. The geometrical analysis shows how the site of the ancient town of Salappya was transformed by Charles I d??Anjou in 1273, renaming it Segine, and how, in about 1500, Alfonso dell??Acaya enlarged the city and its walls according to the same proportional criteria. In 1536 Gian Giacomo dell??Acaya succeeded his father as Baron, redesigning the city walls in order to make them suitable lines of defense against firearms, renaming the city Acaya.     

Visualization of Simulated Urban Spaces: Inferring Parameterized Generation of Streets, Parcels, and Aerial Imagery

Urban simulation models and their visualization are used to help regional planning agencies evaluate alternative transportation investments, land use regulations, and environmental protection policies. Typical urban simulations provide spatially distributed data about number of inhabitants, land prices, traffic, and other variables. In this article, we build on a synergy of urban simulation, urban visualization, and computer graphics to automatically infer an urban layout for any time step of the simulation sequence. In addition to standard visualization tools, our method gathers data of the original street network, parcels, and aerial imagery and uses the available simulation results to infer changes to the original urban layout and produce a new and plausible layout for the simulation results. In contrast with previous work, our approach automatically updates the layout based on changes in the simulation data and thus can scale to a large simulation over many years. The method in this article offers a substantial step forward in building integrated visualization and behavioral simulation systems for use in community visioning, planning, and policy analysis. We demonstrate our method on several real cases using a 200 GB database for a 16,300 km2 area surrounding Seattle, Washington.     

Example‐Driven Procedural Urban Roads

Synthesizing and exploring large‐scale realistic urban road networks is beneficial to 3D content creation, traffic animation and urban planning. In this paper, we present an interactive tool that allows untrained users to design roads with complex realistic details and styles. Roads are generated by growing a geometric graph. During a sketching phase, the user specifies the target area and the examples. During a growing phase, two types of growth are effectively applied to generate roads in the target area; example‐based growth uses patches extracted from the source example to generate roads that preserve some interesting structures in the example road networks; procedural‐based growth uses the statistical information of the source example while effectively adapting the roads to the underlying terrain and the already generated roads. User‐specified warping, blending and interpolation operations are used at will to produce new road network designs that are inspired by the examples. Finally, our method computes city blocks, individual parcels and plausible building and tree geometries. We have used our approach to create road networks covering up to 200 and containing over 3500 km of roads.     

Quantifying and evaluating the space overhead for alternative C++ memory layouts

This paper develops a formalism that precisely characterizes when class tables are required for C++ memory layouts. A memory layout is a particular choice of data structures for implementing run‐time support for object‐oriented languages. We use this formalism to quantify and evaluate, on a set of benchmarks, the space overhead for a set of C++ memory layouts. In particular, this paper studies the space overhead due to three language features: virtual dispatch, virtual inheritance, and dynamic typing. To date, there has been no scientific quantification or evaluation of C++ memory layouts. Our approach can help C++ implementors. This work has already influenced the memory layout design choices in IBM's Visual Age C++ V5 compiler. Applying our approach to a set of five benchmarks, we demonstrate that the impact of object‐oriented space overhead can vary dramatically between applications (ranging from 0.42% to 99.79% for our benchmarks). In particular, applications whose object space is dominated by instances of classes that heavily use object‐oriented language features will be significantly impacted by the choice of a memory layout. Copyright © 2003 John Wiley & Sons, Ltd.     

LLAMA: The low-level abstraction for memory access

The performance gap between CPU and memory widens continuously. Choosing the best memory layout for each hardware architecture is increasingly important as more and more programs become memory bound. For portable codes that run across heterogeneous hardware architectures, the choice of the memory layout for data structures is ideally decoupled from the rest of a program. This can be accomplished via a zero-runtime-overhead abstraction layer, underneath which memory layouts can be freely exchanged. We present the low-level abstraction of memory access (LLAMA), a C++ library that provides such a data structure abstraction layer with example implementations for multidimensional arrays of nested, structured data. LLAMA provides fully C++ compliant methods for defining and switching custom memory layouts for user-defined data types. The library is extensible with third-party allocators. Providing two close-to-life examples, we show that the LLAMA-generated array of structs and struct of arrays layouts produce identical code with the same performance characteristics as manually written data structures. Integrations into the SPEC CPU^® lbm benchmark and the particle-in-cell simulation PIConGPU demonstrate LLAMA's abilities in real-world applications. LLAMA's layout-aware copy routines can significantly speed up transfer and reshuffling of data between layouts compared with naive element-wise copying. LLAMA provides a novel tool for the development of high-performance C++ applications in a heterogeneous environment.     

A Comparison of User-Generated and Automatic Graph Layouts

The research presented in this paper compares user-generated and automatic graph layouts. Following the methods suggested by van Ham et al. (2008), a group of users generated graph layouts using both multi-touch interaction on a tabletop display and mouse interaction on a desktop computer. Users were asked to optimize their layout for aesthetics and analytical tasks with a social network. We discuss characteristics of the user-generated layouts and interaction methods employed by users in this process. We then report on a web-based study to compare these layouts with the output of popular automatic layout algorithms. Our results demonstrate that the best of the user-generated layouts performed as well as or better than the physics-based layout. Orthogonal and circular automatic layouts were found to be considerably less effective than either the physics-based layout or the best of the user-generated layouts. We highlight several attributes of the various layouts that led to high accuracy and improved task completion time, as well as aspects in which traditional automatic layout methods were unsuccessful for our tasks.     

Automated layout design of beam-slab floors using a genetic algorithm

The beam-slab layout design task is an ill-defined problem. As a result, it is difficult to delegate this task to computers. This study proposes a new genetic algorithm to be used to perform this design task. First, a new coding scheme for beam-slab layouts is developed. After that, the beam-slab layout design problem is written as an optimization problem by establishing proper objective and constraint functions. To show the validity of the proposed algorithm, it is used to design beam-slab layouts of several floor plans. The obtained results show that the proposed technique is able to find good beam-slab layouts.