Search

In recent years, the use of crowdsourcing has positively transformed the way geographic information is collected, stored and analyzed. Many countries have promoted and funded research into the potential of using crowdsourcing in various fields of governance. This paper focuses on developing a methodology for fast, low-cost and reliable coastal management for touristic purposes in Greece. In particular, a group of a professional surveyor have developed the methodology and trained two volunteers to collect a variety of data points of interest about a public coastal zone, such as the area size of free and unused public space, rocky areas, parking spaces (organized or not), land use types, build up and green areas, municipal lighting, pedestrian crossing points, beach umbrellas, path routes, street furniture, etc. A pilot case study was compiled for a part of the Athenian Riviera to check the methodology. Derived conclusions point out that the developed methodology may be successfully used for managing the 16,000 km length of the coastal zone of Greece for touristic purposes. Considerations for further improvements to the methodology are given.

The major objective of this research is to investigate the progress of citizen participation in cadastral surveying and to consider ways on how to introduce gamification tools for further improveme...

With the rapid global urbanization, several multi-dimensional complex infrastructures have emerged, introducing new challenges in the management of the vertically stratified buildings spaces. 3D indoor cadastral spaces consist a zestful research topic as their complexity and geometry alterations during time, prevents the assignment of the corresponding Rights, Restrictions and Responsibilities (RRR). In the absence of the necessary horizontal spatial data infrastructure/floor plans their determination is weak. In this paper a fit-for-purpose technical framework and a crowdsourced methodology for the implementation of 3D cadastral surveys focused on indoor cadastral spaces, is proposed and presented. As indoor data capturing tool, an open-sourced cadastral mobile application for Android devices, is selected and presented. An Indoor Positioning System based on Bluetooth technology is established while an innovative machine learning architecture is developed, in order to explore its potentials to automatically provide the position of the mobile device within an indoor environment, aiming to add more intelligence to the proposed 3D crowdsourced cadastral framework. A practical experiment for testing the examined technical solution is conducted. The produced results are assessed to be quite promising.

Over the last half century, the world has witnessed rapid urbanization which is expected to increase over the near future. Use and property rights are reflected as a complex equation of overlapping interests. A fit-for-purpose approach for the initial registration of such rights is of a great importance both in formally and informally developed urban areas, as it may empower tenure security, improve property management, formalize property markets and enable poverty reduction. In this paper a more generalized framework, adjustable to the available cartographic infrastructure and funding availability in each region, for the simultaneous implementation of 2D and 3D property registration, based on a Mobile Cloud Computing (MCC) architecture, is proposed. A Database Management System (DBMS) based on the Land Administration Domain Model (LADM) standard is used for the management and storage of the collected data, while a prototype open-source mobile application for the collection of 2D and 3D crowdsourced cadastral data, the automatic 3D modelling and visualization of 3D property units as block models (LoD1) on a mobile’s phone screen in real-time is developed. A case study for a multi-storey building in an urban area of Athens, Greece, is presented. The first results seem to be interesting and promising. A Strengths, Weaknesses, Opportunities, and Threats (SWOT) assessment of the proposed framework, is conducted. The main conclusions referred to the potential and the perspectives of the proposed technical crowdsourced solution for the initial registration for the implementation of a Fit-For-Purpose 3D cadastral system are presented.

In most countries, three-dimensional (3D) property units are registered utilizing two-dimensional (2D) documentation and textual description. This approach has several limitations as it is unable to represent the actual extent of complicated 3D property units in space. As traditional procedures often lead to increased costs and long delays in 2D cadastral surveying, a fast, cost-effective, and reliable solution is needed to cope with the remaining global cadastral surveying needs. Crowdsourcing has claimed a critical role as a reliable methodology with huge potential regarding the realization of 2D and 3D cadastral registration in both an affordable and a timely manner. Many large modern constructions are now planned and constructed based on BIM technology all over the world. The utilization of 3D digital models, such as building information models (BIMs), and the establishment of a connection with the international standard of the Land Administration Domain Model (LADM) could be a solution for the rapid integration of these units into a 3D crowdsourced cadaster with a better representation of the cadastral boundaries of these units, a detailed visualization of complex infrastructures, and an enhancement in the interoperability between different parties and organizations. In this paper, the potential linkage between the BIM, the LADM, and crowdsourcing techniques is investigated in order to provide an effective technical solution for the integration of large new constructions into 3D crowdsourced cadastral surveys. The proposed framework is tested on a building block in Athens, Greece. The potential, perspectives, and reliability of such an implementation are assessed and discussed.

Coronavirus disease (COVID-19) would be recognized not only as a health crisis but also as a socio-economic emergency situation that brings to mind the concept of “urban resilience.” Social distancing came into the forefront and many countries have been forced to adopt such measures immediately. The measures put in place in Greece were strict; however, they also were among the most proactive in Europe and have been credited on a worldwide level for limiting the spread of the pandemic and kept the number of deaths among the lowest in Europe. Public squares and streets consist of the main components of the public space of a city. The management of public space preoccupied the General Secretariat of Civil Protection but also academics and urban planners in Greece. It is an integrated plan of revival of the historic center that creates new paths for pedestrian and bicycle movement. The “Great Walk” scheme manages to materialize interventions that for decades were not achieved.

Rapidly growing cities, multiple uses of urban space and the complexity of overlapping property rights require various types of rights to be registered and handled in a uniform and reliable way, considering the third dimension. The adoption of automated and low-cost but reliable procedures for cadastral surveys and for the capture and processing of cadastral data, as well as the use of modern Information Technology (IT) tools and m-services, is the beginning of a new cadastral evolution. 3D-crowdsourced cadastral data capture has huge potential and may soon facilitate the work of National Mapping Agencies (NMAs). In this paper, an innovative fit-for-purpose procedure is designed and initially tested that aims to save time and costs and to provide a modern technical solution for the initial collection, registration and visualization of 3D cadastral data. An open-source, mobile application for the acquisition of 3D crowdsourced cadastral data and 3D modelling and visualization of property units is developed, tested and presented. The proposed technical procedure is adjustable and may be used in both the developed and the developing world. The geometric accuracy of the final product depends on the geometric accuracy of the basemaps used. The developed application is tested on a multi-story building in an urban area of Larisa, in Greece. An initial evaluation of the procedure and the final product, in terms of its usability, affordability, reliability and implementation duration, is conducted. The first results are satisfactory and may lead to a fit-for-purpose procedure for a 3D cadastre for all in the future.

The construction sector is of strategic importance for the European Commission. This is the reason why there is a special interest in the development of this sector which is attempting to transform into a more sustainable one in order to face various challenges. In this context, European Directive 2014/24/EU brings to the foreground of the European institutional framework the term building information modelling (BIM), that it is widely used in many countries across Europe. In Greece, the situation seems to be different, not only because it has not been applied in practice but also because of some special features of the way the construction sector functions. This paper presents the BIM use-level in Greece and the way with which it could be better integrated in the construction sector. Through this review we make a brief assessment of the strategy developed in order for the BIM to be integrated in Greek building procedures. Furthermore, we focus on specific issues, like the extended informal housing phenomenon, and on factors that cannot easily be standardized that create problems in BIM use. Finally, through an initial market analysis we underline the role of academic institutions for integrating BIM across Greece.

This paper presents an end-to-end methodology that can be used in the disaster response process. The core element of the proposed method is a deep learning process which enables a helicopter landing site analysis through the identification of soccer fields. The method trains a deep learning autoencoder with the help of volunteered geographic information and satellite images. The process is mostly automated, it was developed to be applied in a time- and resource-constrained environment and keeps the human factor in the loop in order to control the final decisions. We show that through this process the cognitive load (CL) for an expert image analyst will be reduced by 70%, while the process will successfully identify 85.6% of the potential landing sites. We conclude that the suggested methodology can be used as part of a disaster response process.

A ‘fit-for-purpose’ approach is developed, tested and presented for cadastral surveys through increased owners’ participation using new technology and m-government services. Three case studies are reported, for urban, suburban and rural areas, with a combined use of two mobile applications: a commercial software package (ESRI’s Collector for ArcGIS) and an opensource self-developed application named BoundGeometry. The parameters of time, quality and accuracy are assessed and the identified difficulties are classified. It is concluded that the method is applicable both in developed and developing countries, and each time adjustable to the available infrastructure.

The complexity of modern urban environments and civil demands for fast, reliable and affordable decision-making requires not only a 3D Land Information System, which tends to replace traditional 2D LIS architectures, but also the need to address the time and scale parameters, that is, the 3D geometry of buildings in various time instances (4th dimension) at various levels of detail (LoDs - 5th dimension). This paper describes and proposes solutions for technical aspects that need to be addressed for the 5D modelling pipeline. Such solutions include the creation of a 3D model, the application of a selective modelling procedure between various time instances and at various LoDs, enriched with cadastral and other spatial data, and a procedural modelling approach for the representation of the inner parts of the buildings. The methodology is based on automatic change detection algorithms for spatial-temporal analysis of the changes that took place in subsequent time periods, using dense image matching and structure from motion algorithms. The selective modelling approach allows a detailed modelling only for the areas where spatial changes are detected. The procedural modelling techniques use programming languages for the textual semantic description of a building; they require the modeller to describe its part-to-whole relationships. Finally, a 5D viewer is developed, in order to tackle existing limitations that accompany the use of global systems, such as the Google Earth or the Google Maps, as visualization software. An application based on the proposed methodology in an urban area is presented and it provides satisfactory results.

The development of 3D property registration systems is indispensable for the spatial determination of property Rights, Restrictions and Responsibilities (RRR), the sustainable operation of property markets and the safeguarding of ownership in the highly urbanized world. Several developments in computer graphics, 3D modelling and rendering techniques have attracted the growing global interest in 3D cadastre. Since 2012, the Land Administration Domain Model (LADM ISO 19152) is adopted as the international standard for 2D and 3D cadastral data modelling. Developed legal procedures and prototype systems for 3D property rights registration provide interesting solutions for data acquisition and visualization but such approaches are time and cost demanding. In parallel, 2D cadastral surveying procedures have progressed significantly in reducing required time and cost, utilizing crowdsourcing methodology and mobile services. This paper presents a technical solution under development, aiming to provide the beginning for a new era in the initial acquisition, registration and representation of 3D crowdsourced cadastral data, appropriate for both the developed and the developing world. The proposed solution consists of two complementary parts, the technical framework and the crowdsourced methodology to be followed. The technical framework consists of two interconnected parts, the server-side and the client-side. The server-side refers to the Database Management System (DBMS) where the collected data are stored. The client-side refers to the data capturing tool, which in this case is the mobile device. For the server-side, a prototype system based on model driven architecture practices and LADM is developed; while for the client-side, an open-source mobile application for the acquisition of 3D crowdsourced cadastral data, 3D modelling and visualization of 3D property units as block models (LoD1) on a mobile’s phone screen in real-time, is developed. This research is focused on investigating technical aspects for capturing and integrating data about legal rights on physical objects. Detailed investigation of legal issues is not within the objectives of this research. Two case-studies for testing the proposed technical solution are made. An assessment of the current stage of development of the technical solution is presented. The main conclusions converge that the proposed technical solution has huge potentials for the fast, economic implementation of 3D cadastral surveys as it can produce an accurate and reliable 3D information model, depending on the accuracy of the available basemaps. The developed application is easy-to-use as users may not have the necessary level of 3D modelling skills in order to contribute to the registration procedure.

The scope of the paper is to test if the online dynamic maps such as the OpenStreetMap (OSM) can be used for official mapping projects such as Cadastre, to investigate the advantages and the concerns of online and open to the public procedures and to identify those differentiations between experts and amateurs that play a critical role in such official projects. The specific research is focused on the use of OSM in urban areas as an alternative method to the official cadastral surveys. This paper presents the possibilities and the perspectives of OSM for spatial and attribute cadastral data collection and storage for the compilation of draft cadastral maps as an alternative methodology within the terms of the volunteered geographic information (VGI). The authors carried out a practical experiment in an extended part of the historic city centre of Athens and updated the online dynamic map of OSM with attribute and spatial cadastral data. Surveying students explored the capacities of the dynamic map...

The purpose of this research is to identify the differences between the ‘objective’ (tax) values and the current true market values of residential real estate in Greece. For that purpose research is made on the tax values used by tax authorities and the manner of their definition. In the first part of this paper an updated review of all taxes currently levied on residential property in Greece on the transfer (as a property transfer tax) and on the possession of residential properties (as Periodic Annual Taxes) is given. Then the calculation of the ‘tax values’, by the objective mass valuation system of the Greek tax authorities is presented and its variations are explained. In order to investigate the true market values and compare those with the tax values a case study is carried out. The Greater Athens Municipality is chosen because of its size, market importance and diversity. A specific methodology is followed to establish solid criteria for the sample selection, and then the results are compa...

This paper presents the updated findings of a series of research studies conducted within the last seven years by the author on the problem of current informal development in five southeastern European countries with varying political and cultural backgrounds: Montenegro, Albania, Former Yugoslavia Republic of Macedonia, Greece and Cyprus. The paper briefly reviews the main complexities and the variables associated with the issue in an effort to identify how these economies currently respond to informality in terms of regulations, priorities, and legislative and political approaches. It briefly investigates the causes, extent and impact of the problem and it analyses the adopted formalization policies with a purpose to identify good practices and remaining weaknesses.

A ‘fit-for-purpose’ approach is suggested by FIG, the UN and the World Bank as the appropriate methodology for implementing a land administration system depending on a country’s urgent priorities. In this paper, the current official process for the implementation of the Hellenic Cadastre is analyzed and compared to the “fit-for-purpose” model. Some amendments are proposed to replace the initial stage of the data collection official procedure, to make it more fast, efficient and complete. These amendments are tested by a team of researchers of NTUA and the achieved results are presented. The methodology aims to save time, avoid gross errors and additional funds, and provide fast solutions for the completion of the National Cadastral reliably and affordably, during the period of the economic crisis in Greece, with increased citizens’ participation and the use of modern IT tools for the adjudication of the owners, the property rights and the other cadastral data acquisition. New m-services are proposed for the compilation of the cadastral surveys, supported by crowdsourcing techniques. A case study for a suburban area is reported. For the new procedure an open source, self-developed application named BoundGeometry, is used. The new procedure is compared to the official one in terms of time, quality, accuracy and gross errors avoidance. Legal matters related to the adoption of the proposed amendments by the National Cadastral Agency of Greece are also taken into account.

What make citizens participate in mapping projects? What motivates them to get involved in a non-hierarchical network of individuals who collect, edit and share geospatial data? Would they be willing to participate in cadastral mapping as an alternative way to speed up the cadastral survey and minimise the costs and errors which rise when traditional procedures allow limited owners’ participation? The answers are still ambiguous. However, it is a fact that the way geospatial data are used and the way citizens comprehend its importance have changed dramatically during the last years. The paper briefly gives an introduction on the evolution of Neogeography and the citizens’ involvement in spatial data collection, editing and uploading on the web, and of the introduction of the term volunteered geographic information (VGI) and its adoption by the scientific community. The paper then presents the first results of an academic research being compiled at NTUA in collaboration with FIG Com3 WG 3·2. focusi...

This paper presents the results of a 4 year research (Internet, existing literature, interviews with experts from the public and private sectors, Ministry records) on the general legislative and technical aspects and the procedures implemented in Greece, an European Union (EU) member State since 1981. It is a study of compulsory land acquisition and is a case study focused on collecting and analysing recent information about land taking procedures and practices in Greece with an emphasis on current major highway projects. Included is a study of the legal framework; the legislative amendments adopted progressively through recent years; and the existing conflicts among the various Greek courts and the Court of Justice of the European Union and between interpretation of the Greek legislation and the practices in free market economies. Additional problems with the land acquisition process are investigated. This case study focuses on the investigation of emerged problems, and the legislative changes made, due ...

The problem of informal settlements is of significant importance and has similar causes worldwide. In Greece, such buildings are relatively well built and number nearly 1,000,000 across the country. This social and economic issue requires a combined approach. In this paper, a proposed solution to this problem is developed at a technical and administrative level, taking into consideration the criteria of least possible cost and maximum benefit from usage of modern technology. The basic idea is the development of a system that allows for periodic, automatic monitoring and detection of new buildings. With additional field control applied only to specific locations, immediate detection of informal construction projects prior to completion is enabled, at which time measures to halt their development can be more easily taken. The suggested procedure is based on the use of high resolution images and the application of automatic change detection by computation and comparison of digital surface models and building extraction techniques. Results from a pilot application of the proposed procedure are given together with an estimated cost for application of this method to the coastal zone of eastern Attica, a Greek prefecture with many existing and emerging informal constructions.

Digital and automated photogrammetric procedures, developed for the collection and management of spatial data, and terrestrial laser scanning systems provide new capabilities for documentation of archaeological monuments and sites. Also, special tools in Spatial Information Systems and production of virtual models have been developed. Their combination provides relevant scientists (architects, archaeologists, etc) and users with a variety of options for the creation of integrated systems capable for documentation, restoration and cultural development of archaeological sites. Detailed 2D and 3D representation of the current condition of the site, development of a multi-purpose SIS, and introduction of modern digital products at a local museum, such as 3D models, creation of virtual environment and Web applications are some of them. Application of such techniques and systems was made to the archaeological site of the Mycenae in Greece, one of the most important sites worldwide.

Outdoor large-scale cultural sites are mostly sensitive to environmental, natural and human made factors, implying an imminent need for a spatio-temporal assessment to identify regions of potential cultural interest (material degradation, structuring, conservation). On the other hand, in Cultural Heritage research quite different actors are involved (archaeologists, curators, conservators, simple users) each of diverse needs. All these statements advocate that a 5D modelling (3D geometry plus time plus levels of details) is ideally required for preservation and assessment of outdoor large scale cultural sites, which is currently implemented as a simple aggregation of 3D digital models at different time and levels of details. The main bottleneck of such an approach is its complexity, making 5D modelling impossible to be validated in real life conditions. In this paper, a cost effective and affordable framework for 5D modelling is proposed based on a spatial-temporal dependent aggregation of 3D digital models, by incorporating a predictive assessment procedure to indicate which regions (surfaces) of an object should be reconstructed at higher levels of details at next time instances and which at lower ones. In this way, dynamic change history maps are created, indicating spatial probabilities of regions needed further 3D modelling at forthcoming instances. Using these maps, predictive assessment can be made, that is, to localize surfaces within the objects where a high accuracy reconstruction process needs to be activated at the forthcoming time instances. The proposed 5D Digital Cultural Heritage Model (5D-DCHM) is implemented using open interoperable standards based on the CityGML framework, which also allows the description of additional semantic metadata information. Visualization aspects are also supported to allow easy manipulation, interaction and representation of the 5D-DCHM geometry and the respective semantic information. The open source 3DCityDB incorporating a PostgreSQL geo-database is used to manage and manipulate 3D data and their semantics.

In 1994, the Hellenic government, with the support of the European Union, started a project for the establishment of the Hellenic Cadastre (HC), which will be a title registration information system in fully digital form. It is estimated, that this project will last 20 years and it will cover the whole country. So far, digital photogrammetric Cadastral Surveys (CSs), named Pilot Phase and Main Program, of a total area of 893,000 ha have been commissioned and executed in various areas of Greece; 250,000 ha more were commissioned within the year 2000. Through this work, a surprisingly high level of cooperation between the private and public sector has been achieved. This paper focuses on the research and the progress that has been made in all scientific fields, such as the definition of the content of this project, the implementation of the responsible institutions/agencies for the HC, their administrative structure, the proposed regional structure, the development of the National Legal Framework for the compilation of the CSs, the adjudication procedure and maintenance issues. An emphasis is given to the experience so far gained in the legal and technical aspects, and especially to the proposals for an improvement of the methods, and to the attempt to create a cost recovery business culture for maximizing the products and services, which can be supported by the HC. This project requires major international and local experience and a high level of research in all the above mentioned issues, which has to be applied successfully.

Each modern state needs to have a real estate valuation system for purposes of: fair real estate taxation, as a support to the real estate market, for better management of rural or urban environment or any other purpose. This enables a mass valuation system by systematic valuation of groups of real estate units performed on a certain date with the help of standard procedures and statistical analysis. In order to be able to valuate real property its size and value-per-size factor are required. The product of the two multiplied by, for instance, the tax rate yields the amount of tax to be paid, but can also be used for other purposes. As opposed to the tax rate which is defined by legislative acts and the size which can be explicitly quantified (calculated) from its geometry, the value-per-size of real property must be determined based on a predefined set of rules and criteria. Generally, the more rules and criteria included, the more fairly the value can determined. Furthermore, for this value to be as fair as possible, the rules and criteria need to be defined and tested for the entire jurisdiction affected. Real property can generally be seen as land, buildings, and what-ever is attached or affixed to the land. In this research we limit our-selves to land i.e. a part of it defined by a cadastral parcel. Besides the size which is defined by its area, there are other characteristics of a cadastral parcel which explicitly and unambiguously define it. No matter what its purpose may be, the three spatial characteristics which directly influence the value of a piece of land are its azimuth, slope and shape compactness. In this paper we first give a theoretical background for the method for automatic quantification of the mentioned three characteristics, provided cadastral and DTM databases are available in digital form and managed using spatial database management systems (SDBMS) technology. The shape compactness of cadastral parcel is calculated using its area and perimeter. Slope and azimuth are calculated by spatially intersecting triangles from the DTM with the shape of cadastral parcel. Since we wanted a distinct value for the slope and azimuth of each parcel, ’ per parcel’ averages are calculated using the weighted mean of ’ per intersection’ values of slope and azimuth. The area of intersection was used as weight. Finally, a description of a test system based on presented method and implemented on top of Oracle10g SDBMS is given. Within the research a sample DTM and cadastral database have been loaded into the system, and response times to queries for a single cadastral parcel and for a set of 5100 parcels indicate that such a system should be able to function in real world conditions.