A Technique for Building Representation in Oblique View Maps of Modern Urban Areas

Abstract

This paper presents a technique for creating oblique view maps of urban areas. We identify and apply cartographic and cognitive principles to develop a solution in the context of state-of-art geographic information systems. The gap in the ability of these systems to render three-dimensional buildings into maps is addressed. At the core of our solution is a building facade modelling approach that supports varying degrees of abstraction. This is achieved by introducing a concept of 'facade waveforms' and representing building facades as combinations of these waveforms. A Fourier series approximation of the waveforms is used during the rendering processes resulting in an elegant solution to anti-aliasing. The formulation retains the semantic information in the representation that enables meaningful extensions like night time facade generation. The solution is implemented as a pixel shader and therefore leads to a large reduction in texture memory requirement compared with existing building rendering techniques. Additionally, in the case of web based systems, there is significant reduction in bandwidth requirement. We highlight the features of the proposed solution by generating demonstrative maps and images.     

Time and space nonlocalities underlying fractional-derivative models: Distinction and literature review of field applications

We investigate the spatiotemporal nonlocality underlying fractional-derivative models as a possible explanation for regional-scale anomalous dispersion with heavy tails. Properties of four fractional-order advection–dispersion equation (fADE) models were analyzed and compared systematically, including the space fADEs with either maximally positive or negative skewness, the time fADE with a temporal fractional-derivative 0<γ<1$0<\gamma <1$, and the extension of the time fADE with 1<γ<2$1<\gamma <2$. Space fADEs describe the dependence of local concentration change on a wide range of spatial zones (i.e., the space nonlocality), while time fADEs describe dynamic mass exchange between mobile and multiple immobile phases and therefore record the temporal history of concentration “loading” (i.e., the time-nonlocality). We then applied the fADEs as models of anomalous dispersion to four extensively-studied, regional-scale, natural systems, including a hillslope composed of fractured soils, a river with simultaneous active flow zones and various dead-zones, a relatively homogeneous glaciofluvial aquifer dominated by stratified sand and gravel, and a highly heterogeneous alluvial aquifer containing both preferential flowpaths and abundant aquitards. We find that the anomalous dispersion observed at each site might not be characterized reasonably or sufficiently by previous studies. In particular, the use of the space fADE with less than maximally positive skewness implies a spatial dependence on downstream concentrations that may not be physically realistic for solute transport in watershed catchments and rivers (where the influence of dead-zones on solute transport can be described by a temporal, not spatial, fractional model). Field-scale transport studies show that large ranges of solute displacement can be described by a space nonlocal, fractional-derivative model, and long waiting times can be described efficiently by a time-nonlocal, fractional model. The unknown quantitative relationship between the nonlocal parameters and the heterogeneity, and the similarity in concentration profiles that are solutions to the different nonlocal transport models, all demonstrate the importance of distinguishing the representative nonlocality (time and/or space) for any given regional-scale anomalous dispersion process.     

分形法估算分散性污染物的运移时间

污染物运移的分形模型导出一个新的适于任意浓度的污染物运移时间公式.对于一个高度非均质含水层中逐渐形成的污染羽,新公式预算出低浓度更早到达的测点.污染峰或羽的运移时间一般经常从达西定律中采用估算平均孔隙流速法得到,而此估算仅仅提供平均浓度(或污染脉冲的峰值浓度)的运移时间信息.近来,计算出任意浓度的运移时间是一个很直接的过程,并且对一个无反应污染物而言,其突破曲线部分的方程被发展.在文中,我们推导出这些方程去概括污染物运移的分形模型.     

A new efficient Eulerian–Lagrangian localized adjoint method for solving the advection–dispersion equation on unstructured meshes

A new and high efficient scheme is developed for the Eulerian–Lagrangian Localized Adjoint Method (ELLAM) to solve the Advection–Dispersion transport Equation (ADE) on unstructured triangular meshes. To obtain accurate results, the new method requires a very limited number of integration points (usually 1 per element).     

An Application Domain Extension to CityGML for immovable property taxation: A Turkish case study

It is generally acknowledged that immovable property taxes are one of the main revenue sources for local government. The literature emphasizes that the administration of property taxes needs well-developed inventories or registers that provide complete and accurate records of the taxed properties and their legal-economic attributes. This requirement is generally fulfilled by Spatial Data Infrastructures (SDIs) in which the coordinate exchange and sharing of geo-spatial data is provided by separate registers/information systems such as: cadastral systems, building and address registers. Recently, the Open Geospatial Consortium presented a core component of a 3D SDI in the form of an international domain standard for representing, storing and exchanging 3D city models. The CityGML allows the semantic and 3D geometrical representation of physical objects but does not deal with the legal and administrative aspects of the city objects which are required for the process of property taxation. This paper outlines the development of an Application Domain Extension (ADE) for the immovable property taxation domain that expands the CityGML data model with the legal and administrative concepts defined in Turkish Law. The study shows that this ADE could be a 3D national data model for municipal information systems and facilitate a more efficient taxation process, as well as providing data for urban planning, facility management and other municipal services.     

Implementation of CityGML energy application domain extension (ADE) for integration of urban solar potential indicators using object-oriented modelling approach

With the advent of energy rating systems and increased energy efficiency requirements for built environment, the assessment of energy performance of new buildings and refurbishment rates of existing buildings have become an important compliance in the building design process. In order to analyse and simulate the effects of energy-efficient measures for buildings, it is essential to establish spatio-semantic information interoperability between the building design and energy modelling softwares. Data interoperability facilitates different domains to interact with the single building model. The geometrical properties of building semantics such as effective areas exposed to total incident radiation were used as indicators for assessment of seasonal solar potential of buildings. The key urban solar potential indicators were identified based on the semantic components of buildings. The CityGML instance document derived from a proposed energy application domain extension (ADE) conceptual schema could be used as common interoperable model for both the design and energy simulation systems.