THE INFLUENCE OF LEVELS OF DETAIL (LOD0-2) AND BUFFER SIZES ON PARAMETER EFFECTIVENESS FOR FINE DUST DISTRIBUTION MODELLING

Building models represented in CityGML Level of Detail 0 to 2 were used to calculate urban morphological parameters to test their effectiveness of correlation with measured total number concentration of fine dust in Berlin. Land use regression modelling as an alternative to physical based models explains the distribution of urban fine and ultrafine particles applying a multi linear regression model. Descriptive parameters are identified by high correlations with measured fine dust values. Here, different height information and geometry representations from LoD0-LoD2 were used to calculate six parameters associated with the ventilation and advection capacity of an urban environment (‘averaged heights of buildings’, ‘height-width ratio’, ‘porosity’, ‘frontal area index’, and ‘building surfaces’ for wall surfaces and for wall and roof surfaces). Parameters were correlated with measurements of the total number concentration of fine dust in the city of Berlin. Initial results show ambivalent correlations for both, different buffer sizes and implementation of the parameters with building representations in different levels of detail

Stochastic Process Associated with Traveling Wave Solutions of the Sine-Gordon Equation

Stochastic processes associated with traveling wave solutions of the sine-Gordon equation are presented. The structure of the forward Kolmogorov equation as a conservation law is essential in the construction and so is the traveling wave structure. The derived stochastic processes are analyzed numerically. An interpretation of the behaviors of the stochastic processes is given in terms of the equation of motion.Comment: 12 pages, 9 figures; corrected typo

Loewner evolution driven by a stochastic boundary point

We consider evolution in the unit disk in which the sample paths are represented by the trajectories of points evolving randomly under the generalized Loewner equation. The driving mechanism differs from the SLE evolution, but nevertheless solutions possess similar invariance properties.Comment: 23 pages, 6 figure

Conformal invariance in two-dimensional turbulence

Simplicity of fundamental physical laws manifests itself in fundamental symmetries. While systems with an infinity of strongly interacting degrees of freedom (in particle physics and critical phenomena) are hard to describe, they often demonstrate symmetries, in particular scale invariance. In two dimensions (2d) locality often promotes scale invariance to a wider class of conformal transformations which allow for nonuniform re-scaling. Conformal invariance allows a thorough classification of universality classes of critical phenomena in 2d. Is there conformal invariance in 2d turbulence, a paradigmatic example of strongly-interacting non-equilibrium system? Here, using numerical experiment, we show that some features of 2d inverse turbulent cascade display conformal invariance. We observe that the statistics of vorticity clusters is remarkably close to that of critical percolation, one of the simplest universality classes of critical phenomena. These results represent a new step in the unification of 2d physics within the framework of conformal symmetry.Comment: 10 pages, 5 figures, 1 tabl

The Energy Application Domain Extension for CityGML: enhancing interoperability for urban energy simulations

The road towards achievement of the climate protection goals requires, among the rest, a thorough rethinking of the energy planning tools (and policies) at all levels, from local to global. Nevertheless, it is in the cities where the largest part of energy is produced and consumed, and therefore it makes sense to focus the attention particularly on the cities as they yield great potentials in terms of energy consumption reduction and efficiency increase. As a direct consequence, a comprehensive knowledge of the demand and supply of energy resources, including their spatial distribution within urban areas, is therefore of utmost importance. Precise, integrated knowledge about 3D urban space, i.e. all urban (above and underground) features, infrastructures, their functional and semantic characteristics, and their mutual dependencies and interrelations play a relevant role for advanced simulation and analyses. As a matter of fact, what in the last years has proven to be an emerging and effective approach is the adoption of standard-based, integrated semantic 3D virtual city models, which represent an information hub for most of the abovementioned needs. In particular, being based on open standards (e.g. on the CityGML standard by the Open Geospatial Consortium), virtual city models firstly reduce the effort in terms of data preparation and provision. Secondly, they offer clear data structures, ontologies and semantics to facilitate data exchange between different domains and applications. However, a standardised and omni-comprehensive urban data model covering also the energy domain is still missing at the time of writing (January 2018). Even CityGML falls partially short when it comes to the definition of specific entities and attributes for energy-related applications. Nevertheless, and starting from the current version of CityGML (i.e. 2.0), this article describes the conception and the definition of an Energy Application Domain Extension (ADE) for CityGML. The Energy ADE is meant to offer a unique and standard-based data model to fill, on one hand, the above-mentioned gap, and, on the other hand, to allow for both detailed single-building energy simulation (based on sophisticated models for building physics and occupant behaviour) and city-wide, bottom-up energy assessments, with particular focus on the buildings sector. The overall goal is to tackle the existing data interoperability issues when dealing with energy-related applications at urban scale. The article presents the rationale behind the Energy ADE, it describes its main characteristics, the relation to other standards, and provides some examples of current applications and case studies already adopting it

ESTIMATION OF SOLAR ENERGY ON VERTICAL 3D BUILDING WALLS ON CITY QUARTER SCALE

In urban areas, solar energy is one promising source of renewable energy to achieve the EU parliament’s goal of reducing CO2 emissions by 20 % compared to 1990. Although annual radiation on vertical walls is lower than that on roof surfaces, they are larger in area and, therefore may contribute to energy production. On the other hand, the modelling of shadowing effects is cost intensive in an complex urban environment. Here we present a method for the calculation of solar potential on vertical walls for simple 2D maps with additional building height information. We introduced observer point columns that enable a fast decision whether a whole vertical set of observer points is illuminated or not. By the introduction of a maximum shade length, we reduce processing time in ArcGIS. 206,291 points of 130 buildings have been analysed in time steps of 15 minutes resulting in 15 769 pairs of solar angles. Results disprove the potential of vertical walls serving to fill the winter gap of roof mounted solar energy plants. Best wall orientation for the deployment of solar panels are west and east in summer, whereas it is southeast in winter

A TOPOLOGICAL FRAMEWORK FOR THE TEMPORAL ASPECTS OF LANDFORM DEVELOPMENT

Natural landforms are of great importance for a variety of scientific and engineering disciplines. Investigation of landforms can be improved by comparison of features that have similar characteristics, structure and genesis. We propose a novel framework for the representation of the temporal aspects of landform development that simplifies the complex spatial relationships between 3D objects and the modelling of geological processes over time (4D) applying the Poincaré Duality. Single landform layers are represented as nodes (DualStructures) and the neighbourhood of these layers are represented as edges (DualStructureRelations). Finally, a DualStructureState represents a whole landform of stable conditions over a period of time. Change of a landform is represented as additional edges (Abstract_GeoProcess) between the nodes of different layers. The overall structure constitutes a multilayer graph, where all the nodes from all N layers are included but are separated into N partitions of time. All dual representations may be associated with geometric and semantic representations, if available. A formal data model on natural landforms focusing on topological representation is a major step towards the interoperable exchange and comparison of scientific results on landforms. Concerning existing models, our framework can be considered as a superset with regard to model expressivity. This will improve the possibilities to exchange or link data between different application fields

PROPOSAL for A NEW LOD and MULTI-REPRESENTATION CONCEPT for CITYGML

10.5194/isprs-annals-IV-2-W1-3-2016ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences42W13-1

ENHANCED LOD CONCEPTS FOR VIRTUAL 3D CITY MODELS

Virtual 3D city models contain digital three dimensional representations of city objects like buildings, streets or technical infrastructure. Because size and complexity of these models continuously grow, a Level of Detail (LoD) concept effectively supporting the partitioning of a complete model into alternative models of different complexity and providing metadata, addressing informational content, complexity and quality of each alternative model is indispensable. After a short overview on various LoD concepts, this paper discusses the existing LoD concept of the CityGML standard for 3D city models and identifies a number of deficits. Based on this analysis, an alternative concept is developed and illustrated with several examples. It differentiates between first, a Geometric Level of Detail (GLoD) and a Semantic Level of Detail (SLoD), and second between the interior building and its exterior shell. Finally, a possible implementation of the new concept is demonstrated by means of an UML model