# Intelligent Virtual Reality and Augmented Reality Technologies: An Overview
## 3 Result Analysis
### Thematic and Topic Analysis
Particular emphasis is also placed on the design aspects of AI-enriched XR applications and on the importance of human-computer interaction is highlighted. Finally, their role in the industrial sector and security considerations are also increasingly being explored. The related outcomes are further discussed and analyzed in the discussion section. Moreover, the keywords were used to examine the thematic evolution of the topic through the period of 2015-2024. Specifically, the following four time periods were specified: (i) 2015-2018, (ii) 2019-2020, (iii) 2021-2022, and (iv) 2023-2024. Given the limited number of documents published during 2015-2018, the specific time period was not divided any further. Based on the outcomes presented in Figure 8, the following themes arose: (i) \"augmented reality\" and \"virtual reality\" (2015-2018), (ii) \"artificial intelligence\", \"design\", \"visualization\", \"learning systems\", \"robotics\" (2019-2020), (iii) \"virtual reality\", \"machine learning\", \"systems\", \"algorithm\", \"augmented reality\", \"simulation\", \"immersive\", \"impact\", \"internet of things\", \"model\", \"virtual worlds\", \"surgery\", \"real-world\", \"management\", \"object detection\", \"brain\", and \"avatar\" (2021-2022), and (iv) \"virtual reality\", \"surgery\", \"artificial intelligence\", \"impact\", \"education\", \"big data\", \"user interface\", \"recognition\", \"management\", \"e-commerce\", \"challenges\", and \"performance\" (2023-2024). According to the thematic evolution of the topic, the gradual increase in the variety of topics explored can be observed. This fact highlights the wide applicability and potential of using AI within VR and AR environments across different domains and use cases. These outcomes become more evident when considering the trend topics that arose, which can be seen in Figure 9. Specifically, the initial emphasis on machine learning, deep learning, and neural networks has shifted toward a focus on the technologies of AR and VR. Once again, the ability of this combination to be integrated into various domains and transform them is observed with the focus being on education and training, Industry 4.0, and smart cities. However, over the last years (2022-2024), an increasing interest in exploring the field of AI and capitalizing on the use of generative AI within XR environments is observed. Finally, emphasis is also put on further exploring the adoption and use of the metaverse. Figure 8: Thematic evolution of the topic. Finally, the keywords were used to examine the thematic map of the topic and cluster the documents to identify potential areas for future research. Specifically, the thematic map of the topic focuses on identifying the main themes presented within the document collection and divides the themes into Niche, Motor, Basic, and Emerging or Declining themes. Based on the data presented in Figure 10, the following five themes arose: (i) the Niche theme was related to \"education\" and \"training\", (ii) the Motor theme was related to the \"metaverse\", \"digital twins\", \"blockchain\", and \"virtual avatars\", (iii) the Basic themes were related to (a) \"human-computer interaction\" and (b) \"artificial intelligence\", \"extended reality technologies\" (AR, VR, and MR), \"machine learning\", and \"deep learning\", and (iv) the Emerging or Declining theme was related to \"generative artificial intelligence\". These outcomes are in line with the aforementioned results. When clustering the documents based on the keywords used, a total of five clusters emerged all with high impact and centrality. The first cluster was related to: \"virtual environments\" and \"machine learning\" approaches (e.g., adversarial machine learning, contrastive learning, federated learning, etc.). The second cluster was related to \"augmented reality\", \"mixed reality\", \"deep learning\", \"machine learning\", and \"human-computer interaction\".