# Seeking a Definition of Digital Twins for Construction and Infrastructure Management
## 3 Digital Twins Current State of the Art
### Digital Twin Development Frameworks
This application demonstrates Omniverse's capability to support advanced scientific research and engineering projects by providing a realistic, interactive, and high-fidelity digital representation of complex physical systems. Overall, NVIDIA Omniverse offers a powerful and versatile platform for creating, managing, and operating DTs across various industries. Its robust capabilities in real-time simulation, collaboration, and integration with industry-standard tools make it an invaluable asset for advancing technology and improving efficiency. By implementing Omniverse, organisations can expect significant improvements in operational efficiency, reduced costs, and enhanced decision-making capabilities, contributing to overall productivity gains. Microsoft's Azure IoT Hub and Azure Digital Twins (ADTs) [36; 37] provide a robust platform for building, managing, and leveraging DTs across various industries, including construction, smart cities, and manufacturing. These proprietary tools offer comprehensive capabilities and integration options that enhance the creation and utility of DTs. The Azure IoT Hub acts as a central message hub for bi-directional communication between IoT devices and the cloud. It supports protocols like MQTT, AMQP, and HTTPS, ensuring secure and scalable connectivity for numerous devices. This connectivity is crucial for real-time data ingestion, command and control functionalities, and seamless integration with other Azure services. Azure Digital Twins (ADTs) extend these capabilities by offering a rich set of APIs and tools for defining DT models using the Digital Twins Definition Language (DTDL). The DTDL, a JSON-based schema, allows developers to create detailed and custom modelsof physical environments, including their properties, relationships, and behaviours. This flexibility supports a wide range of applications, from simple asset tracking to complex simulations of entire ecosystems. One of the standout features of ADTs is their support for 3D visualisation, which enhances the ability to interact with and analyse DTs in a more intuitive and immersive manner. This is particularly beneficial in construction and BIM, where stakeholders can visualise and simulate building designs, optimise construction processes, and manage facilities with greater efficiency and accuracy. Integration with other Azure services further amplifies the capabilities of ADTs. Azure Functions allows developers to implement custom business logic and event-driven processing, while Azure Stream Analytics, Azure Machine Learning, and Azure Cognitive Services provide powerful tools for real-time data processing, predictive analytics, and advanced machine learning applications. This ecosystem enables the comprehensive monitoring, analysis, and optimisation of DT models. In practical applications, ADTs and the Azure IoT Hub have been used in various innovative projects. For example, Johnson Controls utilises ADTs in their OpenBlue platform to create smart building solutions that enhance operational efficiency and occupant comfort. Thyssenkrupp leverages ADTs to develop DTs for their elevator systems, enabling predictive maintenance and improved service reliability. Similarly, Bentley Systems employs ADTs in their iTwin platform to manage and optimise infrastructure assets, ensuring better performance and reduced lifecycle costs. These technologies are also pivotal in smart city initiatives, where they help in managing urban infrastructure, such as transportation networks, utilities, and public spaces. By creating DTs for these systems, city planners can monitor performance, predict maintenance needs, and optimise resource allocation to improve service delivery and sustainability. In the industrial sector, companies like Ecolab use ADTs for water management solutions, optimising water usage and ensuring compliance with environmental regulations.