# Virtual Reality for Spatial Planning and Emergency Situations: Challenges and Solution Directions
## 6 Conclusions and Future Work  
Multiple challenges and solution directions for using VR for spatial planning and emergency situations were established in this survey. As discussed, the findings can be grouped into four main challenges and solution directions (user experience, collecting results and evaluating the experience) with three further categories of recommendations for other developers (models, game engine and VR).  
Further, during the study, we identified that the link between using VR for smart cities and using VR for emergency evacuation has not yet been fully addressed in other studies. Therefore, this research contributed to closing this research gap. Also, a significant component of the findings could be used for developing VR applications that have other purposes beyond solely spatial planning and emergency situations, and there are also potential benefits for coupling with digital twinning applications within a smart city context [44].  
This article focused on VR due to the technology's advantages over other extended reality technologies, such as augmented reality (AR)- and mixed reality (MR)-based approaches. For example, both AR- and MR-based approaches still require use of the physical world to conduct the study, because the technologies blend digital content with the real-world environment, as discussed in our related work [45]. Additionally, AR, VR and MR could be considered as domains worthy of individual investigations due to their widespread and diverse applications within the smart cities context [46]. Therefore, this article focused only on VR. Extensions of this study could consider including AR and MR in the search query.  
However, the literature review process resulted in findings that are unique specifically to emergency planning research in buildings using VR, for example, the level of detail that is required or how realism should be increased. Despite the general approach that was created from all the findings, it remains a challenge to reach a consensus from the  
Figure 4: Roadmap for VR development.  
papers. All the applications were developed in considerably different ways and using multiple combinations of software. Further, the method for collecting results depended on the research aim and can, therefore, not be generalized.  
For evaluating an application, a general approach should be possible, as all the papers in the literature review used different approaches, with the application of [22] being the most extensively evaluated. Therefore, research on a general approach to the evaluation of comparable applications would be recommended for future work. A limitation of this literature review is that it did not take the grey literature into account. Conducting this could also help with the recommended research that has been mentioned. Thus, future directions for this research could consider the integration of blogs, tutorials and other material in the grey literature to provide a technology-focused roadmap for VR development.  
Conceptualization, R.W., W.H. and F.R.M.; methodology, R.W.; software, R.W.; validation, R.W.; formal analysis, R.W.; investigation, R.W.; resources, R.W.; data curation, R.W.; writing--original draft preparation, R.W.; writing--review and editing, B.T., W.H. and F.R.M.; visualization, R.W.; supervision, W.H. and F.R.M.; project administration, W.H. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest.