scholarly journals EXPLORING THE IMPACT OF VISUAL COMPLEXITY LEVELS IN 3D CITY MODELS ON THE ACCURACY OF INDIVIDUALS’ ORIENTATION AND COGNITIVE MAPS

Author(s):  
V. Rautenbach ◽  
A. Çöltekin ◽  
S. Coetzee

In this paper we report results from a qualitative user experiment (n=107) designed to contribute to understanding the impact of various levels of complexity (mainly based on levels of detail, i.e., LoD) in 3D city models, specifically on the participants’ orientation and cognitive (mental) maps. The experiment consisted of a number of tasks motivated by spatial cognition theory where participants (among other things) were given orientation tasks, and in one case also produced sketches of a path they ‘travelled’ in a virtual environment. The experiments were conducted in groups, where individuals provided responses on an answer sheet. The preliminary results based on descriptive statistics and qualitative sketch analyses suggest that very little information (i.e., a low LoD model of a smaller area) might have a negative impact on the accuracy of cognitive maps constructed based on a virtual experience. Building an accurate cognitive map is an inherently desired effect of the visualizations in planning tasks, thus the findings are important for understanding how to develop better-suited 3D visualizations such as 3D city models. In this study, we specifically discuss the suitability of different levels of visual complexity for development planning (urban planning), one of the domains where 3D city models are most relevant.

Author(s):  
E. Muñumer Herrero ◽  
C. Ellul ◽  
J. Morley

<p><strong>Abstract.</strong> Popularity and diverse use of 3D city models has increased exponentially in the past few years, providing a more realistic impression and understanding of cities. Often, 3D city models are created by elevating the buildings from a detailed 2D topographic base map and subsequently used in studies such as solar panel allocation, infrastructure remodelling, antenna installations or even tourist guide applications. However, the large amount of resulting data slows down rendering and visualisation of the 3D models, and can also impact the performance of any analysis. Generalisation enables a reduction in the amount of data – however the addition of the third dimension makes this process more complex, and the loss of detail resulting from the process will inevitably have an impact on the result of any subsequent analysis.</p><p>While a few 3D generalization algorithms do exist in a research context, these are not available commercially. However, GIS users can create the generalised 3D models by simplifying and aggregating the 2D dataset first and then extruding it to the third dimension. This approach offers a rapid generalization process to create a dataset to underpin the impact of using generalised data for analysis. Specifically, in this study, the line of sight from a tall building and the sun shadow that it creates are calculated and compared, in both original and generalised datasets. The results obtained after the generalisation process are significant: both the number of polygons and the number of nodes are minimized by around 83<span class="thinspace"></span>% and the volume of 3D buildings is reduced by 14.87<span class="thinspace"></span>%. As expected, the spatial analyses processing times are also reduced. The study demonstrates the impact of generalisation on analytical results – which is particularly relevant in situations where detailed data is not available and will help to guide the development of future 3D generalisation algorithms. It also highlights some issues with the overall maturity of 3D analysis tools, which could be one factor limiting uptake of 3D GIS.</p>


Author(s):  
C. Ellul ◽  
M. Adjrad ◽  
P. Groves

There is an increasing demand for highly accurate positioning information in urban areas, to support applications such as people and vehicle tracking, real-time air quality detection and navigation. However systems such as GPS typically perform poorly in dense urban areas. A number of authors have made use of 3D city models to enhance accuracy, obtaining good results, but to date the influence of the quality of the 3D city model on these results has not been tested. This paper addresses the following question: how does the quality, and in particular the variation in height, level of generalization and completeness and currency of a 3D dataset, impact the results obtained for the preliminary calculations in a process known as Shadow Matching, which takes into account not only where satellite signals are visible on the street but also where they are predicted to be absent. We describe initial simulations to address this issue, examining the variation in elevation angle &amp;ndash; i.e. the angle above which the satellite is visible, for three 3D city models in a test area in London, and note that even within one dataset using different available height values could cause a difference in elevation angle of up to 29&amp;deg;. Missing or extra buildings result in an elevation variation of around 85&amp;deg;. Variations such as these can significantly influence the predicted satellite visibility which will then not correspond to that experienced on the ground, reducing the accuracy of the resulting Shadow Matching process.


Author(s):  
K. Arroyo Ohori ◽  
H. Ledoux ◽  
J. Stoter

3D city models of the same region at multiple LODs are encumbered by the lack of links between corresponding objects across LODs. In practice, this causes inconsistency during updates and maintenance problems. A radical solution to this problem is to model the LOD of a model as a dimension in the geometric sense, such that a set of connected polyhedra at a series of LODs is modelled as a single polychoron—the 4D analogue of a polyhedron. This approach is generally used only conceptually and then discarded at the implementation stage, losing many of its potential advantages in the process. This paper therefore shows that this approach can be instead directly realised using 4D combinatorial maps, making it possible to store all topological relationships between objects.


Author(s):  
B. Willenborg ◽  
M. Pültz ◽  
T. H. Kolbe

<p><strong>Abstract.</strong> High-resolution 3D mesh models are an inexpensive and increasingly available data source for 3D models of cities and landscapes of high visual quality and rich geometric detail. However, because of their simple data structure, their analytic capabilites are limited. Semantic 3D city model contain rich thematic information and are well suited for analytics due to their deeply structured semantic data model. In this work an approach for the integration of semantic 3D city models with 3D mesh models is presented. The method is based on geometric distance measures between mesh triangles and semantic surfaces and a region growing approach using plane fitting. The resulting semantic segmentation of mesh triangles is stored in a CityGML data set, to enrich the semantic model with an additional detailed geometric representation of its surfaces and a broad range of unrepresented features like technical building installations, balconies, dormers, chimneys, and vegetation. The potential of the approach is demonstrated on the example of a solar potential analysis, which estimation quality is significantly improved due to the mesh integration. The impact of the method is quantified on a case study using open data from the city of Helsinki.</p>


2018 ◽  
Vol 7 (11) ◽  
pp. 447 ◽  
Author(s):  
Syed Monjur Murshed ◽  
Solène Picard ◽  
Andreas Koch

New planning tools are required to depict the complete building stock in a city and investigate detailed measures on reaching local and global targets to improve energy efficiency and reduce greenhouse gas emissions. To pursue this objective, ISO (the International Organization for Standardization) 13790:2008 monthly heating and cooling energy calculation method is implemented using geometric information from 3D city models (e.g., CityGML format) in an open source software architecture. A model is developed and applied in several urban districts with different number of 3D buildings in various cities. The model is validated with the simulation software TRNSYS. We also perform a sensitivity analysis to quantify the impact of climate change and other physical and behavioral factors on modelling results. The proposed approach can help to perform city or district-wide analysis of the building energy needs and prepare different renovation plans to support decision-making, which finally will enhance the livability of a city and the quality of life of the citizens.


Urban Science ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 4 ◽  
Author(s):  
Syed Murshed ◽  
Alice Duval ◽  
Andreas Koch ◽  
Philipp Rode

Sustainable development of cities and the overall efficiency of urban infrastructure have emerged as central issues in policy consideration. Consequently, investigating the influence of urban physical form on resource use is critical. This paper investigates energy use due to vertical mobility in the context of Asia’s diverging cities. Micro mobility of citizens’ movement in the vertical direction has a distinct impact on the total energy consumption of a city or urban block. The objective of this research is to analyse the impact of different urban morphologies on vertical mobility—from buildings to urban blocks. A methodology is proposed to calculate energy consumption of lifts, based on a detailed review of literature, codes of practice, the International Organisation for Standardisation (ISO)/DIS 25745-1 standard and 3D city models. Furthermore, a tool is developed and applied in 20 typical urban blocks in four cities: Kuwait, Abu Dhabi, Hong Kong and Singapore. The average annual specific energy consumption of lifts varies significantly across the samples. A comparative analysis of all the morphologies across these cities help to understand the impact of building forms, usage, and a number of further parameters on the energy consumption for vertical mobility.


Author(s):  
C. García-Sánchez ◽  
S. Vitalis ◽  
I. Paden ◽  
J. Stoter

Abstract. Climate change and urbanization rates are transforming urban environments, making the use of 3D city models in computational fluid dynamics (CFD) a fundamental ingredient to evaluate urban layouts before construction. However, current geometries used in CFD simulations tend to be built by CFD experts to test specific cases, most of the times oversimplifying their designs due to lack of information or in order to reduce complexity. In this work we explore what are the effects of oversimplifying geometries by comparing wind simulations of different level of detail geometries. We use semantic 3D city models automatically built and adjust them to their suitable use in CFD. For the first test, we explore wind simulations within a troublesome section of the TUDelft campus, the passage next to the EWI building (the tallest building in our domain), where the use of 3D city model variants show how differences in geometry and surface properties affect local wind conditions. Finally we analyze what these differences in velocity magnitude could mean for practitioners in terms of pedestrian wind comfort.


Author(s):  
U. Ujang ◽  
S. Azri ◽  
M. Zahir ◽  
A. Abdul Rahman ◽  
T. L. Choon

<p><strong>Abstract.</strong> Urban Heat Island (UHI) phenomenon has been a topic of intense study over the past several years. However, to visualise UHI model is still an issue. Common visualisation of UHI by using digital thematic maps shows that it is hard to perceive its impacts especially in a sophisticated micro-area such as in urbanized cities. Moreover, different building façade’s material gives different UHI value. Therefore, there is a need in computing and visualising this phenomenon in three-dimensional (3D) perspectives. Recently, the development of 3D city modelling shows the potential of solving these gaps. This can be seen from the characteristics of 3D city models that are suitable in representing micro-areas (complex cities) for UHI studies. Based on this issue, this research aims to produce a 3D UHI model by using 3D city models as a tool for efficient and sustainable building design. The main objective is to produce a new approach in visualising UHI in 3D perspectives by instigating 3D city models. Thus, the UHI effect could be predicted precisely by calculating the building façades value. This research explores the 3D shadow analysis, 3D solar radiation and 3D orientation analysis in UHI modelling via 3D city models. From the analyses, the results show that the 3D city models are capable in presenting the solar radiation value for each building façade. Furthermore, this approach can be used to simulate future UHI analysis-prediction and advantageous for pre-development planning.</p>


2015 ◽  
Vol 26 (3-4) ◽  
pp. 116-123
Author(s):  
A. P. Korzh ◽  
T. V. Zahovalko

Recently, the number of published works devoted to the processes of synanthropization of fauna, is growing like an avalanche, which indicates the extreme urgency of this theme. In our view, the process of forming devices to coexist with human and the results of his life reflects the general tandency of the modern nature evolution. Urbanization is characteristic for such a specific group of animals like amphibians, the evidence of which are numerous literature data. Many researchers use this group to assess the bioindicative quality of the environment. For this aim a variety of indicators are used: from the cellular level of life of organization up to the species composition of the group in different territories. At the same time, the interpretation of the results is not always comparable for different areas and often have significantly different interpretations by experts. Urban environment, primarily due to the contamination is extremely aggressive to amphibians. As a consequence, the urban populations of amphibians may be a change in the demographic structure, affecting the reproductive ability of the population, the disappearance of the most sensitive species or individuals, resizing animals, the appearance of abnormalities in the development, etc. At the same time play an important amphibians in the ecosystems of cities, and some species in these conditions even feel relatively comfortable. Therefore, it is interesting to understand the mechanisms of self-sustaining populations of amphibians in urban environments. To assess the impact of natural and anthropogenic factors on the development of amphibian populations were used cognitive modeling using the program Vensim PLE. Cognitive map of the model for urban and suburban habitat conditions were the same. The differences concerned the strength of connections between individual factors (migration, fertility, pollution) and their orientation. In general, factors like pollution, parasites, predators had negative impact on the population, reducing its number. The birth rate, food and migration contributed to raising number of individuals. Some of the factors affected on the strength to of each other as well: the majority of the factors affected the structure of the population, had an influence on the fertility. Thanks to it the model reflects the additive effect of complex of factors on the subsequent status of the population. Proposed and analyzed four scenarios differing strength and duration of exposure. In the first scenario, a one-time contamination occurs and not subsequently repeated. The second and third scenario assumes half board contamination, 1 year (2 scenario) and two years (scenario 3). In the fourth scenario, the pollution affected the population of amphibians constantly. In accordance with the results of simulation, much weaker than the natural populations respond to pollution - have them as an intensive population growth and its disappearance at constant pollution is slow. Changes to other parameters of the model showed that this pollution is the decisive factor -only the constant action leads to a lethal outcome for the populations. All other components of the model have a corrective effect on the population dynamics, without changing its underlying trand. In urban areas due to the heavy impact of pollution maintaining the population is only possible thanks to the migration process – the constant replenishment of diminishing micropopulations of natural reserves. This confirms the assumption that the form of existence metapopulations lake frog in the city. In order to maintain the number of amphibians in urban areas at a high level it is necessary to maintain existing migration routes and the creation of new ones. Insular nature of the placement of suitable habitats in urban areas causes the metapopulation structure of the types of urbanists. Therefore, the process of urbanization is much easier for those species whicht are capable of migration in conditions of city. In the initial stages of settling the city micropopulationis formed by selective mortality of the most susceptible individuals to adverse effects. In future, maintaining the categories of individuals is provided mainly due to migration processes metapopulisation form of the species of existence is supported). It should be noted that the changes in the previous levels are always saved in future. In the case of reorganizations of individuals we of morphology can assume the existence of extremely adverse environmental conditions that threaten the extinction of the micropopulations. 


2020 ◽  
Vol 8 (3) ◽  
pp. 3-17
Author(s):  
Elena Blagoeva

The impact of the last global economic crisis (2008) on the European economy put a strain on higher education (HE), yet it also pushed the sector towards intensive reforms and improvements. This paper focuses on the “Strategy for the Development of Higher Education in the Republic of Bulgaria 2014-2020”. With a case study methodology, we explore the strategic endeavours of the Bulgarian government to comply with the European directions and to secure sustainable growth for the HE sector. Our research question is ‘How capable is the Bulgarian HE Strategy to overcome the economic and systemic restraints of Bulgarian higher education?’. Because the development of strategies for HE within the EU is highly contextual, a single qualitative case study was chosen as the research approach. HE institutions are not ivory towers, but subjects to a variety of external and internal forces. Within the EU, this is obviated by the fact that Universities obtain their funds from institutions such as governments, students and their families, donors, as well as EU-level programmes. Therefore, to explore how these pressures interact to affect strategic action on national level, the case method is well suited as it enabled us to study the phenomena thoroughly and deeply. The paper suggests the actions proposed within the Strategy have the potential to overcome the delay, the regional isolation and the negative impact of the economic crisis on the country. Nevertheless, the key elements on which the success or failure of this Strategy hinges are the control mechanisms and the approach to implementation. Shortcomings in these two aspects of strategic actions in HE seem to mark the difference between gaining long-term benefits and merely saving face in front of international institutions.


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