Abstract
The perception that we have of our world depends on the task we are currently performing in the environment, so if we are driving a car we will pay attention to the objects that are visually important to the task we are performing such as, the road, road signs, other vehicles, etc. The same is true when we explore virtual environments. The creation of high-fidelity 3D maps on mobile devices to aid navigation in urban environments is computationally very expensive, precluding achieving this quality at interactive rates. In this paper we present a case study to show how the human visual system may be exploited, when viewers are undertaking a task, to reduce the overall quality of the displayed image, without the users being aware of this reduction in quality. The displayed images are selectively rendered with the key features used to identify location and orientation in a 3D urban environment produced in high quality and the remainder of the image in low quality.

Abstract
Finding one's way around an unfamiliar city can be a major challenge. While maps can provide a very good abstract representation of our world, and a simple and efficient way to navigate within that world, they are of little use when, for example, the absence of road signs prevents us from locating where we are on the map. Mobile devices offer the potential for providing relevant 3D information to enable us to locate ourselves, rapidly navigate around an unfamiliar environment and explore it interactively. However, mobile devices are constrained by resources such as bandwidth, storage and small displays. In this paper we investigate which is the most important visual information for position location within an unfamiliar urban environment and show how we can use this knowledge to provide a perceptually high quality 3D virtual environment on existing mobile devices. Copyright 2004 ACM.

Abstract
A map can be a major advantage when exploring unfamiliar environments. With the proliferation of mobile devices, such as PDAs and even mobile phones, the tourist industry is currently exploring the potential of new presentation strategies that will maximize the promotional appeal of tourism in their region. Mobile devices are capable of guiding a tourist when he/she is exploring a city. These mobile devices offer the potential for providing relevant 3D information to enable tourists to locate themselves within the city, rapidly navigate around the unfamiliar environment and explore it interactively. However, the computational resources of current mobile technology prevents the display of full complex 3D content in real-time, and thus selective rendering techniques must be adopted to ensure the viewer is provided with the perceptually most important information at interactive rates. This paper presents a series of experiments which help to identify key features of a scene for users to orientate themselves in that environment. Knowledge of these salient key features enable them to be provided to a user at a high quality while the remainder of the scene can be rendered in a much lower quality, saving significant bandwidth and computing power, without the user being perceptually aware of this difference in quality within the image.

Abstract
This paper presents Geospatial L-systems, a new extension of L-systems that incorporates geospatial awareness, and shows an application of this new tool in the expeditious modelling of urban environments, integrated with a modelling system with interoperable access to data sources. L-systems have been used in Computer Graphics for the modelling of plants, and in a few experiments to model urban environments. However, the lack of geospatial awareness is a limitation and in spite of some developments like open l-systems introduced the ability to communicate with the environment, there was a need for more flexibility. A new modelling system, named XL3D, generates virtual urban environments automatically from a XL3D document with a modelling specification. This modelling system accesses data sources in a interoperable way and the modelling processes are based on L-systems. The integration of geospatial L-systems with the XL3D modelling system has increased its potential for automation and improved the potential to generate virtual urban environments with a higher level of detail and visual fidelity, with a lower level of complexity of the modelling processes. These facts are shown in a case study where a virtual urban environment taken from an area in the Porto downtown is generated by this solution. © The Eurographics Association 2006.

Abstract
L-systems have been used in Computer Graphics, namely for modelling plants, as well as in a few experiments to model urban environments. However, the lack of geospatial awareness is a limitation and in spite of some developments like open L-systems, that introduced the ability to communicate with the environment, there was a need for more flexibility. This paper presents Geospatial L-systems, a new extension of L-systems that incorporates geospatial awareness, and shows an application in the area of expeditious modelling of urban environments. A modelling system, named XL3D, generates virtual urban environments automatically from a XML based document that contains a modelling specification and accesses data sources in an interoperable way. The integration of geospatial L-systems in this modelling system has increased the potential for automation and the potential to generate virtual urban environments with a higher level of detail and visual fidelity, with a lower level of complexity of the modelling processes. These facts are shown in a case study where a virtual urban environment, taken from an area in the Porto downtown, is generated by this solution.

Abstract
During the health crisis caused by COVID-19, virtual reality (VR) proved to be useful for the tourism industry, allowing this industry to continue working despite the restrictions imposed. However, it remains to be seen if the impact of this sanitary crisis in the tourism industry influenced managers' intention to adopt this technology in the post-pandemic period. To fill this gap, a qualitative methodological approach was adopted, using the MAXQDA20 software and interviews with managers of tourism enterprises. The results show that the willingness to invest in technology, the perception of VR as a business strategy, and the perception of the impact of the pandemic are factors that regulate the intention of companies to adopt VR. In addition, prior experience with VR and the perception of technical support are also important for its adoption. Thus, it was concluded that VR can be a valuable sustainable strategy for tourism companies to address the challenges imposed by the pandemic. However, adopting the technology depends on factors such as financial availability, business strategy, and previous experience with VR. Furthermore, tourism companies must also receive adequate technical support to ensure its correct implementation.