3D representations of large-scale and urban scenes are crucial across various industries, including autonomous driving, urban planning, natural resource supervision and many more. Large-scale industrial reconstructions are inherently complex and multifaceted. Many existing surveys primarily focus on academic progressions and often neglect the intricate and diverse needs of industry. This survey aims to bridge this gap by providing a comprehensive analysis of 3D reconstruction methods, with a focus on industrial requirements such as scalability and integration of human interaction. Our approach involves utilizing Affinity Diagramming to systematically analyze qualitative data gathered from industrial partners. This methodology enables us to gain deep insights into how recent literature addresses these specific industrial needs. The survey encompasses various aspects, including input and reconstruction modalities, architectural models, datasets, evaluation metrics, and the incorporation of prior knowledge. We further discuss practical implications derived from our analysis, highlighting key considerations for future advancements in 3D reconstruction methods tailored for large-scale applications.

The vision of the Internet of Things (IoT), supported by industrial companies and governments all over the world, marks an evolution that will surely have a great impact on our environments and our lives. The central element of this vision is the existence of a network of interconnected objects (electrical appliances, wearable devices, industrial machinery, etc). Under the context of the IoT, these objects not only can exchange data anytime and anywhere, but also collaborate in the provisioning of novel services. In fact, some of these services are already available: web-based portals that enable the creation of aggregated services using world-wide sensor data, industrial systems that enable the development of preventive maintenance processes, and many others. However, protecting the IoT is a complex and difficult task. The current Internet is already under constant attack due to a mixture of several factors: technical (e.g. vulnerable systems, unsecure protocols), legal (e.g. jurisdiction problems), and human (e.g. targeted attacks, usability problems).The Internet of Things will not only inherit these problems, but will also have some important issues of its own. The heterogeneity of protocols and devices will make the development of interoperable, fault-tolerant security services a daunting task. The connectivity that is crucial to the IoT will make critical infrastructures extremely vulnerable against cascade failures. Moreover, as the IoT will process countless bits of personal data, the management of personal privacy might become a nightmare. The purpose of this special issue is to introduce six research articles whose goal is to provide solutions to some of the most urgent problems related to IoT security: secure communications, authentication and authorization, user privacy, and security assessment. Moreover, in line with the inherent heterogeneity of the IoT, this special issue will not focus on one single technology, but will provide an analysis of several protocols and systems (RFID systems, sensor networks, critical infrastructures). The contributions of these papers are outlined in the succeeding text. As Radio Frequency Identification (RFID) systems can be considered as one of the foundational stones of the IoT, it is important to develop a communication system that enables RFID tags to securely connect to the Internet. That is precisely the goal of the article entitled “Secure communication with RFID tags in the internet of things”, by Dominikus and Kraxberger. In this article, the authors develop Mobile-IPv6 enabled RFID tags, which can connect to the Internet through RFID readers. Moreover, these tags can also integrate end-to-end IPsec security services, effectively protecting the information exchange between the tags and the remote servers. Wireless sensor networks, or WSN, can also be considered as one of the essential elements of the IoT. These resource-constrained networks usually make use of the IPv6 over Low-power Wireless Personal Area Networks (6LoWPAN) protocol to connect to external Internet hosts. However, this protocol does not explicitly define an IPsec extension. Therefore, Shahid et al. analyzed how IPsec could be successfully integrated in 6LoWPAN in their article “Secure communication for the Internet of Things - A comparison of Link-Layer security and IPsec for 6LoWPAN”. Their analysis shows how IPsec can be a feasible option for securing the IoT in terms of performance and scalability. As aforementioned, privacy is one of the most important research challenges in the context of the IoT. More specifically, in the case of RFID systems, it is essential to develop security mechanisms that avoid user data to be leaked to unauthorized parties. This special issue introduces two mechanisms that provide efficient solutions to this particular problem. In “How to protect security and privacy in the IoT: A policy-based RFID tag management protocol”, Rekleitis, Rizomiliotis and Gritzalis provide a desirable set of management operations (from delegation of querying rights to ownership transfer) that allow users to manage their own set of RFID tags. On the other hand, in “A context-aware approach to defend against unauthorized reading and relay attacks in RFID systems”, Ma and Saxena make use of on-board sensors to provide contextual information to the RFID tags. This contextual information can be used to develop enhanced authorization policies, such as selective unlocking according to location. These two functions, authorization and context awareness, are also studied by Bai et al. in “Context-Aware Usage Control for Web of Things”. In this article, the authors develop a model that enables users to define their own context-aware security policies. Such policies are then applied to Internet-connected “intranet of things” environments, like smart homes. In fact, the authors provide an example of a working prototype, which enables users to control the appliances of their smart home in an intelligent and secure way. Finally, in “Assessing the Security of Internet Connected Critical Infrastructures”, Ghani et al. develop a set of security metrics that can be used to monitor the integrity of Internet-connected Critical Infrastructures (CIs). In particular, the authors first define a set of metric-based Service-Level Agreements (SLAs), which capture the user requirements of all CIs. Afterwards, a metrics monitoring system receives the measures from various sensors, which are then compared to the SLAs. Consequently, the system can detect potential problems before they happen – and act before a cascade event further damages the integrity of the CIs. We would like to express our gratitude to Professor Hsiao-Hwa Chen and Professor Hamid R. Sharif, Editors-in-Chief of the Security and Communication Networks journal, for their support before and during the development of this special issue. We would also like to thank the authors that chose to publish their research findings in this special issue. The Internet of Things is in dire need of strong security foundations, and we believe these research results will help to build a more secure future. Finally, we would like to thank all the reviewers that, with their time and their comments, helped the authors to strengthen their security protocols and mechanisms.

The convergence of multiple paradigms, visions, and technologies – Internet of Things (IoT) and Web of Things (WoT); Ambient Intelligence (AmI); Machine-to-Machine (M2M); and many others – is giving birth to a world of interconnected things. A world where any entity (be it a machine, an object, a person, or anything) can collaborate with each other, anytime and anywhere, in the provisioning of services. This concept of a truly interconnected world is at its infancy, yet there are various commercial players pushing previously envisioned services to the real world: from centralized Big Data repositories to “intranet of things” systems, from industrial information services to personal wearable sensor systems. Moreover, this evolution does not stop here, as the scientific community is constantly researching new advances in this area. Additionally, there is a factor that must not be overlooked in the development of this interconnected world: security. To truly understand the importance of this factor, we just need to check the state of another interconnected infrastructure: the current Internet. While functional and resilient, the current Internet is still a target of malicious attacks that affect both its users and its infrastructure. However, the scope of a truly interconnected world goes well beyond the current Internet: encompassing a global interoperable connectivity and accessibility by a myriad of heterogeneous entities, with countless data streams that can be aggregated and processed when necessary. Without the proper fault-tolerant security mechanisms, all this wealth of services and information might be not only accessed by users but also manipulated by malicious attackers. Precisely, due to the existence of such information flows, we also cannot let privacy go unnoticed in the development of security solutions for this particular context. Not only are the personal data of users at stake (e.g. daily life, medical records, private information), but also the confidential information managed by larger entities. Consequently, the purpose of this special issue is to introduce six research articles that study how to protect users and devices in the context of an interconnected world, with a special emphasis on privacy-preserving solutions. The contributions of these papers are outlined in the succeeding text. The privacy challenges are not only daunting, but also uncharted. Who are the stakeholders? What concrete threats exist, and how can they be defined? What is the impact of these threats? How can the stakeholders react against these threats? The goal of the article entitled “Privacy in the Internet of Things: Threats and Challenges”, by Ziegeldorf, Garcia-Monchon, and Wehrle, is to provide detailed answers to all these questions. Note that, even if the article focuses specifically on the Internet of Things, most of its analysis can be applied to all the other paradigms that compose this interconnected vision – as they share various underlying principles such as heterogeneous connectivity. In an interconnected world, it is essential for the devices to route the information to each other. One possible solution, which has been studied for years in the area of big distributed infrastructures, are P2P overlay networks. Still, there are several challenges in this area, such as how to manage the users’ identities while preserving their anonymity, and the existence of various attacks that can manipulate how identities are assigned (e.g. Sybil, Eclipse, MITM). The purpose of the paper entitled “RIAPPA: a Robust Identity Assignment Protocol for P2P overlays”, by Caubet et al., is to provide a generic, not algorithm-dependant protocol that can deal with these challenges. In the exchange of information between things, it is not only important to provide anonymity when necessary, but also to maintain a certain Quality of Service (QoS) to avoid excessive service degradation. The goal of the paper entitled “On Collaborative Anonymous Communications in Lossy Networks”, by Rebollo-Monedero et al., is to introduce a Crowds-like protocol for anonymous communication that establishes quantifiable metrics of anonymity and QoS. Such metrics enable the authors to perform a detailed mathematical analysis of the protocol, effectively improving the scope of the original Crowds protocol while achieving a reasonable balance between anonymity and QoS. In fact, due to the importance of maintaining a reasonable QoS while applying the security protocols, this special issue includes the paper entitled “Analysis and Taxonomy of Security/QoS tradeoff solutions for the Future Internet”, by Nieto and Lopez. This paper provides a thorough analysis of the coexistence of security and QoS mechanisms within the context of Future Internet scenarios. The paper analyses existing solutions and identifies potential problems, and also describes the major pitfalls in the integration of existing networking models such as Wireless Sensor Networks (WSN) and Cellular networks. Most of the previous papers focus on anonymity. But there are other privacy issues that must be taken into vaccount. For example, by continuously querying the network about several topics, users can be profiled – which in some cases might reveal bits of information even more important and private than our identities. The paper entitled “Enhancing Information Lookup Privacy through Homomorphic Encryption”, by Fotiou et al., provides a broker-based solution to this problem. Such a solution is also optimized, achieving a balance between the complexity of the computations and the communication overhead between the involved parties. Finally, if the networked embedded systems that comprise our interconnected world are not properly designed to comply with various security properties, attackers will surely find their way to break into them – no matter what security and privacy protocols are developed. The article entitled “Integrating security mechanisms into embedded systems by domain-specific modeling”, by Vasilevskaya et al., combine security and software engineering solutions (e.g. Model-based development (MBD), information security ontology) in order to allow system designers to easily integrate security requirements during the design process. We would like to express our gratitude to Professor Hsiao-Hwa Chen and Professor Hamid R. Sharif, Editors-in-Chief of the Security and Communication Networks journal, for their support before and during the development of this special issue. We would also like to thank the authors that chose to publish their research findings in this special issue, as a truly interconnected world is within our grasp – but we must find ways to protect it before it becomes a liability rather than a blessing. Finally, we would like to thank all the reviewers that, with their time, efforts, and their comments, helped the authors to strengthen their security protocols and mechanisms.

ABSTRACT Because the Internet of Things (IoT) pervasively extends to all facets of life, the “things” are increasingly extending to include the interconnection of the Internet to critical infrastructures (CIs) such as telecommunication, power grid, transportation, e‐commerce systems, and others. The objective of this paper is twofold: (i) addressing IoT from a CI protection (CIP) and connectivity viewpoint, and (ii) highlighting the need for security quantification to improve the quality of protection (QoP) of CIs. Using a financial infrastructure as an example, a CIP and trust quantification perspective is built up. To this end, we are developing a novel security metrics‐based approach to assess and thereon enhance the CIP. We focus on the communication level of the CI where IoT is playing an increasingly important role with respect to sensing and communication across CI elements. Determining the security and dependability level of the communication over the CI constitutes a basic precondition for assessing the QoP of the whole CI, which is needed for any efforts to improve this QoP. Because metrics play a central role for such quantification, this paper develops their QoP use from an IoT perspective, and a reference implementation along with experimental results is presented. Copyright © 2012 John Wiley & Sons, Ltd.

Sentence compression holds promise for many applications ranging from summarization to subtitle generation. The task is typically performed on isolated sentences without taking the surrounding context into account, even though most applications would operate over entire documents. In this article we present a discourse-informed model which is capable of producing document compressions that are coherent and informative. Our model is inspired by theories of local coherence and formulated within the framework of integer linear programming. Experimental results show significant improvements over a state-of-the-art discourse agnostic approach.

Sentence compression holds promise for many applications ranging from summarization to subtitle generation. Our work views sentence compression as an optimization problem and uses integer linear programming (ILP) to infer globally optimal compressions in the presence of linguistically motivated constraints. We show how previous formulations of sentence compression can be recast as ILPs and extend these models with novel global constraints. Experimental results on written and spoken texts demonstrate improvements over state-of-the-art models.

Sentence compression is the task of producing a summary at the sentence level. This paper focuses on three aspects of this task which have not received detailed treatment in the literature: training requirements, scalability, and automatic evaluation. We provide a novel comparison between a supervised constituent-based and an weakly supervised word-based compression algorithm and examine how these models port to different domains (written vs. spoken text). To achieve this, a human-authored compression corpus has been created and our study highlights potential problems with the automatically gathered compression corpora currently used. Finally, we assess whether automatic evaluation measures can be used to determine compression quality.