Extended Reality (XR) means any technology that allows the user to visualize and interact within a merge between the real world and virtual worlds created on a computer.  XR applications are usually classified into three types: virtual reality (VR), augmented reality (AR), and mixed reality (MR). This Special Issue will accept papers that address the following aspects:

First, specific applications of XR in urban environments. For example, accessibility analysis of spaces, a preview of public works, visualization and interaction in Building Information Modelling (BIM models), maintenance and preservation of urban spaces, improvement of the tourist offer quality, interfaces for smart cities, etc.

Secondly, works related to technical issues for the generation of XR applications.  The special characteristics of the urban environments (spaces that are open, extensive, and complex) necessitates the search for new approaches and technological solutions. These include, for example, the selection of the most suitable remote sensors for data acquisition (Terrestrial Laser Scanning (TLS), Aerial Laser Scanning (ALS), etc.) or the adaptation of the generated 3D models to the virtual environment. Concerning HMI, issues have arisen such as the development of algorithms or the choice of the optimal sensors for interaction in the virtual world (cameras, gloves, active or passive beacons, virtual or hardware beacons, etc.).

Finally, review articles on state-of-the-art technology related to the scope of this Special Issue will also be welcome.

• Remote sensing for 3D modeling
• TLS
• ALS
• 3D visualization
• Sensor fusion
• Localization
• Human-machine interfaces
• Haptic
• Virtual reality
• Augmented reality
• Mixed reality
• Urban environments
• Urban accessibility
• XR tourism
• Smart cities