scholarly journals A REQUIREMENT ANALYSIS ON EXTENDING SEMANTIC 3D CITY MODELS FOR SUPPORTING TIME-DEPENDENT PROPERTIES

2019 ◽  
Vol IV-4/W9 ◽  
pp. 19-26 ◽  
Author(s):  
K. Chaturvedi ◽  
T. H. Kolbe
Keyword(s):  
Semantic Information ◽  
Smart Cities ◽  
Data Models ◽  
Time Dependent ◽  
Systematic Analysis ◽  
3D City Models ◽  
Semantic Data ◽  
Different Types ◽  
Support Time ◽  
City Models

Abstract. Semantic 3D City Models are used worldwide for different application domains ranging from Smart Cities, Simulations, Planning to History and Archeology. Well-defined data models like CityGML, IFC and INSPIRE Data Themes allow describing spatial, graphical and semantic information of physical objects. However, cities and their properties are not static and change with respect to time. Hence, it is important that such semantic data models handle different types of changes that take place in cities and their attributes over time. This paper provides a systematic analysis and recommendations for extensions of Semantic 3D City Models in order to support time-dependent properties. This paper reviews different application domains in order to identify key requirements for temporal and dynamic extensions and proposes ways to incorporate these extensions. Over the last couple of years, different extensions have been proposed for these standards to deal with temporal attributes. This paper also presents an analysis to which degree these extensions cover the requirements for dynamic city models.

scholarly journals PROCESSING OF CRAWLED URBAN IMAGERY FOR BUILDING USE CLASSIFICATION

2017 ◽  
Vol XLII-1/W1 ◽  
pp. 143-149
Author(s):  
P. Tutzauer ◽  
N. Haala
Keyword(s):  
Semantic Information ◽  
Smart Cities ◽  
Image Interpretation ◽  
Ground Truth ◽  
Training Data ◽  
Proof Of Concept ◽  
Huge Amount ◽  
Semantic Data ◽  
New Applications ◽  
City Models

Recent years have shown a shift from pure geometric 3D city models to data with semantics. This is induced by new applications (e.g. Virtual/Augmented Reality) and also a requirement for concepts like Smart Cities. However, essential urban semantic data like building use categories is often not available. We present a first step in bridging this gap by proposing a pipeline to use crawled urban imagery and link it with ground truth cadastral data as an input for automatic building use classification. We aim to extract this city-relevant semantic information automatically from Street View (SV) imagery. Convolutional Neural Networks (CNNs) proved to be extremely successful for image interpretation, however, require a huge amount of training data. Main contribution of the paper is the automatic provision of such training datasets by linking semantic information as already available from databases provided from national mapping agencies or city administrations to the corresponding façade images extracted from SV. Finally, we present first investigations with a CNN and an alternative classifier as a proof of concept.

scholarly journals SOLAR POTENTIAL ANALYSIS AND INTEGRATION OF THE TIME-DEPENDENT SIMULATION RESULTS FOR SEMANTIC 3D CITY MODELS USING DYNAMIZERS

2017 ◽  
Vol IV-4/W5 ◽  
pp. 25-32 ◽  
Author(s):  
K. Chaturvedi ◽  
B. Willenborg ◽  
M. Sindram ◽  
T. H. Kolbe
Keyword(s):  
Phase 1 ◽  
International Standards ◽  
Time Dependent ◽  
3D City Models ◽  
Wide Range ◽  
Domain Extension ◽  
Simulation Results ◽  
The City ◽  
Support Time ◽  
City Models

Semantic 3D city models play an important role in solving complex real-world problems and are being adopted by many cities around the world. A wide range of application and simulation scenarios directly benefit from the adoption of international standards such as CityGML. However, most of the simulations involve properties, whose values vary with respect to time, and the current generation semantic 3D city models do not support time-dependent properties explicitly. In this paper, the details of solar potential simulations are provided operating on the CityGML standard, assessing and estimating solar energy production for the roofs and facades of the 3D building objects in different ways. Furthermore, the paper demonstrates how the time-dependent simulation results are better-represented inline within 3D city models utilizing the so-called Dynamizer concept. This concept not only allows representing the simulation results in standardized ways, but also delivers a method to enhance static city models by such dynamic property values making the city models truly dynamic. The dynamizer concept has been implemented as an Application Domain Extension of the CityGML standard within the OGC Future City Pilot Phase 1. The results are given in this paper.

scholarly journals MODELLING CHANGES, STAKEHOLDERS AND THEIR RELATIONS IN SEMANTIC 3D CITY MODELS

2021 ◽  
Vol VIII-4/W2-2021 ◽  
pp. 137-144
Author(s):  
S. H. Nguyen ◽  
T. H. Kolbe
Keyword(s):  
Change Detection ◽  
Smart Cities ◽  
Deep Understanding ◽  
Structural Level ◽  
Mathematical Methods ◽  
Conceptual Approach ◽  
3D City Models ◽  
Digital Twins ◽  
Virtual City ◽  
City Models

Abstract. Urban digital twins have been increasingly adopted by cities worldwide. Digital twins, especially semantic 3D city models as key components, have quickly become a crucial platform for urban monitoring, planning, analyses and visualization. However, as the massive influx of data collected from cities accumulates quickly over time, one major problem arises as how to handle different temporal versions of a virtual city model. Many current city modelling deployments lack the capability for automatic and efficient change detection and often replace older city models completely with newer ones. Another crucial task is then to make sense of the detected changes to provide a deep understanding of the progresses made in the cities. Therefore, this research aims to provide a conceptual framework to better assist change detection and interpretation in virtual city models. Firstly, a detailed hierarchical model of all potential changes in semantic 3D city models is proposed. This includes appearance, semantic, geometric, topological, structural, Level of Detail (LoD), auxiliary and scoped changes. In addition, a conceptual approach to modelling most relevant stakeholders in smart cities is presented. Then, a model - reality graph is used to represent both the different groups of stakeholders and types of changes based on their relative interest and relevance. Finally, the study introduces two mathematical methods to represent the relevance relations between stakeholders and changes, namely the relevance graph and the relevance matrix.

scholarly journals INVESTIGATING INTEROPERABILITY CAPABILITIES BETWEEN IFC AND CITYGML LOD 4 – RETAINING SEMANTIC INFORMATION

2018 ◽  
Vol XLII-4/W10 ◽  
pp. 33-40 ◽  
Author(s):  
G. S. Floros ◽  
C. Ellul ◽  
E. Dimopoulou
Keyword(s):  
Semantic Information ◽  
Open Data ◽  
3D Models ◽  
Solar Panels ◽  
3D City Models ◽  
Information Models ◽  
Building Information ◽  
Consistent Manner ◽  
3D Information ◽  
City Models

<p><strong>Abstract.</strong> Applications of 3D City Models range from assessing the potential output of solar panels across a city to determining the best location for 5G mobile phone masts. While in the past these models were not readily available, the rapid increase of available data from sources such as Open Data (e.g. OpenStreetMap), National Mapping and Cadastral Agencies and increasingly Building Information Models facilitates the implementation of increasingly detailed 3D Models. However, these sources also generate integration challenges relating to heterogeneity, storage and efficient management and visualization. CityGML and IFC (Industry Foundation Classes) are two standards that serve different application domains (GIS and BIM) and are commonly used to store and share 3D information. The ability to convert data from IFC to CityGML in a consistent manner could generate 3D City Models able to represent an entire city, but that also include detailed geometric and semantic information regarding its elements. However, CityGML and IFC present major differences in their schemas, rendering interoperability a challenging task, particularly when details of a building’s internal structure are considered (Level of Detail 4 in CityGML). The aim of this paper is to investigate interoperability options between the aforementioned standards, by converting IFC models to CityGML LoD 4 Models. The CityGML Models are then semantically enriched and the proposed methodology is assessed in terms of model’s geometric validity and capability to preserve semantics.</p>

scholarly journals Building Virtual 3D City Model for Smart Cities Applications: A Case Study on Campus Area of the University of Novi Sad

2020 ◽  
Vol 9 (8) ◽  
pp. 476 ◽  
Author(s):  
Dušan Jovanović ◽  
Stevan Milovanov ◽  
Igor Ruskovski ◽  
Miro Govedarica ◽  
Dubravka Sladić ◽  
...  
Keyword(s):  
Smart Cities ◽  
Airborne Lidar ◽  
3D City Models ◽  
3D City Model ◽  
City Model ◽  
Novi Sad ◽  
The University ◽  
The City ◽  
City Models

The Smart Cities data and applications need to replicate, as faithfully as possible, the state of the city and to simulate possible alternative futures. In order to do this, the modelling of the city should cover all aspects of the city that are relevant to the problems that require smart solutions. In this context, 2D and 3D spatial data play a key role, in particular 3D city models. One of the methods for collecting data that can be used for developing such 3D city models is Light Detection and Ranging (LiDAR), a technology that has provided opportunities to generate large-scale 3D city models at relatively low cost. The collected data is further processed to obtain fully developed photorealistic virtual 3D city models. The goal of this research is to develop virtual 3D city model based on airborne LiDAR surveying and to analyze its applicability toward Smart Cities applications. It this paper, we present workflow that goes from data collection by LiDAR, through extract, transform, load (ETL) transformations and data processing to developing 3D virtual city model and finally discuss its future potential usage scenarios in various fields of application such as modern ICT-based urban planning and 3D cadaster. The results are presented on the case study of campus area of the University of Novi Sad.

scholarly journals A 3D CAMPUS APPLICATION BASED ON CITY MODELS AND WEBGL

2018 ◽  
Vol XLII-5 ◽  
pp. 161-165 ◽  
Author(s):  
M. Buyukdemircioglu ◽  
S. Kocaman
Keyword(s):  
Semantic Information ◽  
Geographical Information ◽  
Data Types ◽  
3D City Models ◽  
Gis Applications ◽  
Technological Developments ◽  
Gis Environment ◽  
Virtual Platform ◽  
Application Fields ◽  
City Models

<p><strong>Abstract.</strong> In parallel with the technological developments, the conventional ways of mapping and the presentation of the geospatial data have changed significantly. 3D city models including the digital terrain models (DTMs) have become important for many application fields, such as simulation and visualization tasks for navigation, urban planning, environmental monitoring, disaster management, etc. Although currently most 3D city models are employed for visualization purposes, their application areas are increasing continuously. The presentation of these models on the web is also becoming more common than before while overcoming the performance issues with newer data types and functionalities. The biggest advantage of using web browsers is that they can be accessed everywhere without any additional software requirements. Therefore, the tools for web-based implementations of virtual globes, which allow users to navigate their data in 3D, have been available with greater numbers of functionality they offer. Online virtual web globes provide a good base for the 3D Geographical Information System (GIS) applications as well. 3D city models have also become virtual environments where different spatial queries and analysis can be performed. As a part of a 3D WebGIS, a city model enriched with semantic information provides a virtual platform for decision makers and allows realistic simulations for planning. The main aims of this study are to develop a prototype of a 3D GIS environment for Hacettepe University Beytepe campus, including 3D building geometries enriched with semantic information and a high resolution DTM; and to design a web interface using an open source virtual globe.</p>

scholarly journals Incorporating Topological Representation in 3D City Models

2019 ◽  
Vol 8 (8) ◽  
pp. 347 ◽  
Author(s):  
Stelios Vitalis ◽  
Ken Ohori ◽  
Jantien Stoter
Keyword(s):  
Data Structure ◽  
Data Model ◽  
Semantic Information ◽  
Semantic Representation ◽  
Geometric Analysis ◽  
Computationally Efficient ◽  
Real World Data ◽  
3D City Models ◽  
Map Data ◽  
City Models

3D city models are being extensively used in applications such as evacuation scenarios and energy consumption estimation. The main standard for 3D city models is the CityGML data model which can be encoded through the CityJSON data format. CityGML and CityJSON use polygonal modelling in order to represent geometries. True topological data structures have proven to be more computationally efficient for geometric analysis compared to polygonal modelling. In a previous study, we have introduced a method to topologically reconstruct CityGML models while maintaining the semantic information of the dataset, based solely on the combinatorial map (C-Map) data structure. As a result of the limitations of C-Map’s semantic representation mechanism, the resulting datasets could suffer either from semantic information loss or the redundant repetition of them. In this article, we propose a solution for a more efficient representation of geometry, topology and semantics by incorporating the C-Map data structure into the CityGML data model and implementing a CityJSON extension to encode the C-Map data. In addition, we provide an algorithm for the topological reconstruction of CityJSON datasets to append them according to this extension. Finally, we apply our methodology to three open datasets in order to validate our approach when applied to real-world data. Our results show that the proposed CityJSON extension can represent all geometric information of a city model in a lossless way, providing additional topological information for the objects of the model.

scholarly journals INFERRING ROOF SEMANTICS FOR MORE ACCURATE SOLAR POTENTIAL ASSESSMENT

2021 ◽  
Vol XLVI-4/W4-2021 ◽  
pp. 33-37
Author(s):  
I. Apra ◽  
C. Bachert ◽  
C. Cáceres Tocora ◽  
Ö. Tufan ◽  
O. Veselý ◽  
...  
Keyword(s):  
Point Cloud ◽  
Semantic Information ◽  
Renewable Energy Sources ◽  
Energy Transition ◽  
Urban Landscapes ◽  
Solar Panels ◽  
3D City Models ◽  
Additional Information ◽  
Open Datasets ◽  
City Models

Abstract. In guiding the energy transition efforts towards renewable energy sources, 3D city models were shown to be useful tools when assessing the annual solar energy generation potential of urban landscapes. However, the simplified roof geometry included in these 3D city models and the lack of additional semantic information about the buildings’ roof often yield less accurate solar potential evaluations than desirable. In this paper we propose three different methods to infer and store additional information into 3D city models, namely on physical obstacles present on the roof and existing solar panels. Both can be used to increase the accuracy of roof solar panel retrofit potential. These methods are developed and tested on the open datasets available in the Netherlands, specifically AHN3 lidar point-cloud and PDOK aerial photography. However, we believe they can be adapted to different environments as well, based on the available datasets and their precision locally available.

scholarly journals Services Oriented Smart City Platform Based On 3d City Model Visualization

2014 ◽  
Vol II-4 ◽  
pp. 59-64 ◽  
Author(s):  
F. Prandi ◽  
M. Soave ◽  
F. Devigili ◽  
M. Andreolli ◽  
R. De Amicis
Keyword(s):  
Spatial Data ◽  
Smart City ◽  
Smart Cities ◽  
Geographical Information ◽  
Data Infrastructure ◽  
3D City Models ◽  
3D City Model ◽  
Key Factor ◽  
City Model ◽  
City Models

The rapid technological evolution, which is characterizing all the disciplines involved within the wide concept of smart cities, is becoming a key factor to trigger true user-driven innovation. However to fully develop the Smart City concept to a wide geographical target, it is required an infrastructure that allows the integration of heterogeneous geographical information and sensor networks into a common technological ground. In this context 3D city models will play an increasingly important role in our daily lives and become an essential part of the modern city information infrastructure (Spatial Data Infrastructure). <br><br> The work presented in this paper describes an innovative Services Oriented Architecture software platform aimed at providing smartcities services on top of 3D urban models. 3D city models are the basis of many applications and can became the platform for integrating city information within the Smart-Cites context. <br><br> In particular the paper will investigate how the efficient visualisation of 3D city models using different levels of detail (LODs) is one of the pivotal technological challenge to support Smart-Cities applications. The goal is to provide to the final user realistic and abstract 3D representations of the urban environment and the possibility to interact with a massive amounts of semantic information contained into the geospatial 3D city model. <br><br> The proposed solution, using OCG standards and a custom service to provide 3D city models, lets the users to consume the services and interact with the 3D model via Web in a more effective way.

scholarly journals GEOSPATIAL DATA FOR ENERGY EFFICIENCY AND LOW CARBON CITIES – OVERVIEW, EXPERIENCES AND NEW PERSPECTIVES –

2018 ◽  
Vol XLII-4 ◽  
pp. 467-474
Author(s):  
A. Nowacka ◽  
F. Remondino
Keyword(s):  
Energy Efficiency ◽  
Smart Cities ◽  
Google Earth ◽  
Geospatial Data ◽  
Urban Spaces ◽  
Spatial Analyses ◽  
Low Carbon ◽  
3D City Models ◽  
Related Data ◽  
City Models

<p><strong>Abstract.</strong> The use of Geographic Information Systems (GIS) and their integration with 3D city models have become a common and powerful asset of cities for planning, visualization and decision-making operations in the fields of energy management, energy efficiency as well as transportation, public infrastructures, etc. The use of such solutions in urban spaces is still confined and mainly applied to visualization purposes (e.g. Google Earth) although geodata and spatial analyses can solve many problems towards the creation of smart cities. This paper presents an overview of various activities using spatial and non-spatial energy-related data integrated with 3D city models into GIS environments. It reviews existing solutions and reports two ongoing projects which deal with geospatial data for better planning and management of energy efficient public lighting and almost zero-consumption public buildings.</p>

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