Integration of Immersive Approaches for Collaborative Processes with Building Information Modeling (BIM) Methodology for the AEC Industry: An Analysis of the Current State and Future Challenges

: This study aims to identify and analyze existing gaps in the integration of immersive approaches for collaborative processes with Building Information Modeling (BIM) in the Architecture, Engineering, and Construction (AEC) sector. Using a systematic approach that includes metadata analysis and review procedures, we have formulated speciﬁc research questions aimed at guiding future investigations into these gaps. Additionally, the analysis generates insights that could guide future research directions and improvements in the ﬁeld. The methodology involves a comprehensive review of the literature, focusing on the interaction between immersiveness, BIM methodology, and collaborative processes. Data from 2010 to 2023 have been analyzed to ensure relevance and completeness. Our ﬁndings reveal current limitations in the ﬁeld, such as the need for fully integrated prototypes and the execution of empirical studies to clarify operational processes. These limitations serve as the basis for our research questions. The study offers actionable insights that could guide future research and improvements in the AEC sector, particularly in the adoption of immersive technologies. The research underscores the urgency of addressing these challenges to facilitate ongoing development and greater adoption of immersive technologies in the AEC sector.


Introduction
The construction industry is undergoing an unprecedented technological transformation, with a series of innovations seeking to integrate into the complex processes of the AEC industry, from BIM methodology to blockchain, and more recently, the metaverse [1,2].Despite these innovations representing a turning point for the sector, analyses conducted by the McKinsey Global Institute (MGI) show that the construction industry lags behind other sectors in terms of technological advancement and digitalization.
This fact, as highlighted by industry experts [2][3][4][5][6], raises important questions about the significance and complexity of implementing such innovations in the daily practice of the construction industry.These changes, involving technical and procedural aspects, are making and will continue to make the use of technology and digitalization increasingly accessible and intuitive for everyone [7].
A tangible example of this transformation is the BIM methodology and its recent developments, including the implementation of the Level of Information Need introduced by the UNI EN 17412-1 regulation.This level of detail allows for the clear and unambiguous management and access to project or object information [8].
In addition to these innovations, the use of immersive technologies, such as virtual reality and augmented reality (AR/VR), represents a significant advancement both technologically and procedurally in collaborative processes [9][10][11].These technologies offer new and unexplored immersive ways to engage stakeholders in projects through the integration of VR/AR applications with BIM [12].
In our context, by immersiveness we mean an experience that intensely engages the user's senses, creating a sense of physical presence in a virtual or mixed environment.This can extend beyond VR headsets to AR platforms and technologies, which allow for sensory interaction with data and information.As for collaborative processes, we refer to activities involving multiple parties collaborating to achieve a common goal in the lifecycle of a BIM project.This includes information sharing, activity coordination, and collective decision-making.In our context, our focus is on the integration of immersive technologies in a collaborative environment, an area still in the developmental stage.
However, in the practical application of these immersive technologies, significant challenges arise in bridging the gap from theory to practice.The gap between the theoretical concept and practical implementation is well documented in numerous studies [13][14][15].These challenges result from various technical and procedural factors, including the complexity of effectively integrating BIM collaborative processes with immersive technologies.This process requires investments in terms of necessary equipment and required skills, and often, it is unclear what the expected end result should be or what the maturity level of immersive information should be [16,17].
This research aims to examine the state of the art in this field, outlining the current application of immersive technologies in collaborative processes with BIM methodology and seeking to identify solutions to fill existing gaps.The research focuses on three main contexts: BIM, Immersivity, and Collaborative Processes.The research question that emerged from the literature review, which will be subject to further investigation, is as follows: "How does the use of immersive technologies in collaborative processes with BIM methodology require specific information and/or data to be correctly applied?" From this main question that emerged following the analyses conducted, three subquestions have also been structured: 1.
What information and/or data are required to correctly apply immersive technologies in combination with BIM methodology?2.
Is there a specific "Level of Immersion Requirements" for these applications?3.
If so, how is this "Level of Immersion Requirements" defined and applied?
In the next section, we will analyze the theoretical context and the current state of research on BIM, Immersivity, and Collaborative Processes, introducing a research methodology approach.We will also describe the analysis and review method used to discuss the current results.Finally, we will provide a summary of the findings and conclusions, discussing the innovative contribution of this work and its limitations.

Background 2.1. Background and Challenges to Implementing Building Informational Modeling
Over the past thirty years, technological progress has led to a proliferation of software and plugins that have significantly improved the management of design, modeling, and graphical rendering in the AEC industry [13].These developments have been further enhanced by the introduction of BIM and computational design, revolutionizing the design and decision-making process across all phases, from construction to demolition [18].
BIM has successfully addressed many historical challenges in the construction sector by improving coordination among various stakeholders, optimizing resource and time allocation, and enhancing safety through improved activity visualization [19].Furthermore, BIM has played a central role in academic research, as demonstrated by projects like H2020 BIM4EEB (BIM-based tools & technologies for fast and efficient Energy Performance Renovation in Buildings) [20].
It's important to note that the regulatory framework is becoming increasingly structured, with standards such as ISO 19650 [21] and UNI EN 17412-1 [22] guiding the digital transition in the AEC industry.In particular, UNI EN 17412-1 has outlined the informational process required during collaborative phases of BIM processes.Additionally, ISO 16739-1:2018 [23] introduced a standard for data sharing, Industry Foundation Classes (IFC), playing a fundamental role in promoting interoperability between different software and data sharing throughout various project phases [24].
However, as our research focus highlights, challenges remain in integrating BIM with immersive technologies for effective collaborative processes.
Despite the considerable progress made so far, we are faced with a significant challenge: the management of digital data, often complex and fragmented, is becoming increasingly resource-intensive and potentially error-prone [13].To successfully address this challenge, it is imperative to carefully examine the integration of new techniques and tools through research.A promising solution to address this challenge is the adoption of immersive technologies and virtual worlds, which enable advanced visualization and optimal management of complex data.These environments not only overcome the limitations of traditional technologies but also promote a deep understanding of data by integrating data knowledge with perception [2].This is directly related to our research objective of examining the current state and gaps in integrating immersive technologies and BIM into collaborative processes.
These interactions between various technologies and methodologies are creating new professional roles, such as "Metaverse Architects", who will operate in new fields, such as Virtual World, BIM 2.0 [25], Digital Creation, Digital Asset, Digital Market, and Digital Currency [26].This shifts the focus of information, which is not only understood by the user but also perceived, generating different outputs.Ultimately, the combined adoption of these innovations, such as the integration of BIM and immersive technologies, is radically changing how the AEC industry operates.However, challenges remain related to the limited knowledge of the virtual world and the need to establish clearer standards for widespread adoption [27].

Background and Challenges to Implementing Immersiveness
The sharing of data and models in the virtual world has become a topic of great relevance in recent years, in parallel with the increasing adoption of Immersive Technologies such as Virtual Reality, Augmented Reality, and Mixed Reality [13].These technologies are gradually overcoming initial challenges and limitations related to data management, representation quality, information quantity, and functional performance, thanks to ongoing technological advancements [28].In particular, the involvement of tech giants like Google, Facebook, Microsoft, Nvidia, and Autodesk is contributing to making these technologies more accessible globally, with examples such as Google Cardboard headsets becoming available at affordable costs, allowing anyone to experience an initial immersion into the virtual world.
The increasingly widespread adoption of immersive technologies is evident from data provided by the International Data Corporation (IDC), which predicts significant growth in the wearables market in the near future [29,30].These visualization tools offer an ideal means to engage stakeholders in all phases of a construction (AEC) project, addressing the problem of stakeholder engagement [31].
Some studies have demonstrated the effectiveness of virtual environments for managing models at various levels of detail, safety training, site layout planning, collision detection, and more [32][33][34].Research has also been conducted on collaboration and model management in virtual environments among different stakeholders [35], as well as on decision-making aspects [36] and educational contexts [37][38][39].
However, it is crucial to understand the differences between various immersive technologies, such as VR, AR, and MR, and the emerging concept of the Metaverse [40].The choice among these technologies depends on the specific application (Figure 1).Further-more, it is essential to clarify the terminology used, as there is a variety of terms often used improperly in the AEC industry, such as "immersive technologies", "immersive environments", "virtual environments", and "immersive realities", which can be confusing and make their application and expected outcomes challenging [41].For example, Virtual Reality offers a qualitative representation of spaces at full scale, allowing users to explore them as if they were on-site and facilitating stakeholder engagement [42,43].On the other hand, Augmented Reality and Mixed Reality blend the real world with the virtual, enabling the analysis of informational-geometric aspects [44][45][46].make their application and expected outcomes challenging [41].For example, Virtual Reality offers a qualitative representation of spaces at full scale, allowing users to explore them as if they were on-site and facilitating stakeholder engagement [42,43].On the other hand, Augmented Reality and Mixed Reality blend the real world with the virtual, enabling the analysis of informational-geometric aspects [44][45][46].
However, there are still challenges related to the limited knowledge of the virtual environment by participants, the lack of standards in the AEC industry, and the fragility of currently available devices [13].Despite numerous advantages, it is apparent that immersive technologies have not yet been widely adopted in practical design, mainly due to a lack of understanding of their benefits and the challenges associated with widespread adoption [13,47].Therefore, it is essential to investigate in this field, seeking to clarify the aspects that limit their mass adoption.As suggested by our research objective, the lack of specific information levels for the correct use of these technologies in collaborative BIM processes represents a gap in the current state of the art.

Background and Challenges to Implementing Collaboration Process
Regarding the AEC industry, the updating of collaborative and decision-making processes using advanced technologies, such as VR and AR, is receiving more and more attention, even if the literature on this topic is currently limited to applications in the AEC industry [48].However, some research has demonstrated the importance of integrating collaborative processes in the construction industry with advanced technologies like immersive approaches [49][50][51][52][53].This aligns with our research objective of identifying gaps and solutions in the application of immersive technologies in BIM-based collaborative processes.However, there are still challenges related to the limited knowledge of the virtual environment by participants, the lack of standards in the AEC industry, and the fragility of currently available devices [13].Despite numerous advantages, it is apparent that immersive technologies have not yet been widely adopted in practical design, mainly due to a lack of understanding of their benefits and the challenges associated with widespread adoption [13,47].Therefore, it is essential to investigate in this field, seeking to clarify the aspects that limit their mass adoption.As suggested by our research objective, the lack of specific information levels for the correct use of these technologies in collaborative BIM processes represents a gap in the current state of the art.

Background and Challenges to Implementing Collaboration Process
Regarding the AEC industry, the updating of collaborative and decision-making processes using advanced technologies, such as VR and AR, is receiving more and more attention, even if the literature on this topic is currently limited to applications in the AEC industry [48].However, some research has demonstrated the importance of integrating collaborative processes in the construction industry with advanced technologies like immersive approaches [49][50][51][52][53].This aligns with our research objective of identifying gaps and solutions in the application of immersive technologies in BIM-based collaborative processes.
Studies, like the one conducted by Berg et al. [54], have highlighted how immersive environments can influence decision-making processes and increase stakeholder engage-ment.These environments offer a representation of spaces that engages users more deeply, improving understanding of issues and stimulating more effective discussions.
Furthermore, immersive technology can simplify the decision-making process when dealing with complex issues, as demonstrated by Sangiorgio et al. [55] in the context of energy retrofitting of buildings.This technology provides a vast amount of visual information and allows for the perception of data, making the evaluation of design options more accessible.The use of virtual prototypes is another tool that can facilitate understanding the implications of design decisions, as highlighted by Huang et al. [56].Additionally, virtual environments can be used to gather feedback from clients and stakeholders, as shown by Berg et al. [57].
Much of the current research focuses on the application of virtual worlds in educational settings, construction coordination, BIM-based collision control, real estate management, healthcare simulation, and athletic training.For example, Heydarian et al. [58] used virtual environments to collect data on occupant preferences regarding lighting.Schneider et al. [59] developed a BIM-based framework for user evaluation in complex buildings through virtual environments.Hilfert et al. [60] implemented fully immersive VR systems to simulate building usage scenarios, such as emergency situations.However, in practical terms, there is a lack of significant application of immersive technologies in collaborative and decision-making processes, creating many limitations and gaps in the literature [61].This observation is directly related to our research objective, which aims to address these limitations and gaps.

Research Methodology
In alignment with the specific objectives of this research, we identified three primary thematic areas: BIM, Immersivity, and Collaborative Processes.Particular emphasis was placed on tailoring these areas to meet the unique needs of the AEC sector, while also taking into account technological advancements.These three dimensions serve as the foundational basis for our data collection and analysis.Our aim is not only to review existing frameworks but also to propose concrete solutions and recommendations for future research.To achieve this objective, we adopted a methodological framework divided into five phases, as shown in Figure 2.These phases are interconnected in an iterative cycle, allowing for a continuous review and refinement of our research.
Studies, like the one conducted by Berg et al. [54], have highlighted how immersive environments can influence decision-making processes and increase stakeholder engagement.These environments offer a representation of spaces that engages users more deeply, improving understanding of issues and stimulating more effective discussions.
Furthermore, immersive technology can simplify the decision-making process when dealing with complex issues, as demonstrated by Sangiorgio et al. [55] in the context of energy retrofitting of buildings.This technology provides a vast amount of visual information and allows for the perception of data, making the evaluation of design options more accessible.The use of virtual prototypes is another tool that can facilitate understanding the implications of design decisions, as highlighted by Huang et al. [56].Additionally, virtual environments can be used to gather feedback from clients and stakeholders, as shown by Berg et al. [57].
Much of the current research focuses on the application of virtual worlds in educational settings, construction coordination, BIM-based collision control, real estate management, healthcare simulation, and athletic training.For example, Heydarian et al. [58] used virtual environments to collect data on occupant preferences regarding lighting.Schneider et al. [59] developed a BIM-based framework for user evaluation in complex buildings through virtual environments.Hilfert et al. [60] implemented fully immersive VR systems to simulate building usage scenarios, such as emergency situations.However, in practical terms, there is a lack of significant application of immersive technologies in collaborative and decision-making processes, creating many limitations and gaps in the literature [61].This observation is directly related to our research objective, which aims to address these limitations and gaps.

Research Methodology
In alignment with the specific objectives of this research, we identified three primary thematic areas: BIM, Immersivity, and Collaborative Processes.Particular emphasis was placed on tailoring these areas to meet the unique needs of the AEC sector, while also taking into account technological advancements.These three dimensions serve as the foundational basis for our data collection and analysis.Our aim is not only to review existing frameworks but also to propose concrete solutions and recommendations for future research.To achieve this objective, we adopted a methodological framework divided into five phases, as shown in Figure 2.These phases are interconnected in an iterative cycle, allowing for a continuous review and refinement of our research.This approach has enabled us to formulate research questions that address current gaps in the state of the art.These gaps include the incomplete integration of immersive technologies into BIM workflows and the absence of well-defined information requirements and procedures to support collaborative processes involving immersive This approach has enabled us to formulate research questions that address current gaps in the state of the art.These gaps include the incomplete integration of immersive technologies into BIM workflows and the absence of well-defined information requirements and procedures to support collaborative processes involving immersive technologies.These questions will underpin future research endeavors, offering a clear roadmap for both academic and industrial efforts going forward.
After evaluating the context of the current landscape and its inherent challenges, we conducted a literature review to structure an overview of the existing state of the art.As previously said, to achieve the specific aims of our research, we employed a methodological framework divided into five phases, as depicted in Figure 2.
The first phase involved a comprehensive study of the state of the art, conducted through unrestricted searches on various search engines and academic databases such as Scopus and Web of Science.The aim was to identify the current landscape and its associated challenges.The second phase focused on defining a structured data collection strategy, which included keyword and author searches.The third phase concentrated on the evaluation of the collected data.The fourth phase dealt with the analysis and interpretation of the literature, employing SWOT Analysis as a methodological tool.The fifth and final phase led to the formulation of the research question.
We opted for a mixed-methods approach for several reasons.Firstly, using both qualitative and quantitative data allows us to attain a more comprehensive and holistic understanding of the phenomenon under examination.Secondly, while quantitative data provide a solid foundation for generalizations, qualitative data offers the context and depth necessary to grasp the nuances and specificities of our research field.These two types of data are integrated in order to provide a complete view of the phenomenon under consideration.Finally, the mixed methods approach proves particularly useful for triangulating the results, thus improving the validity and reliability of our research and formulating questions that respond to real gaps in the state of the art.
Among the techniques employed for the collection, assessment, and analysis of literary sources, we utilized PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) [62], SWOT (Strengths, Weaknesses, Opportunities, and Threats) [13], and scientometric analysis.PRISMA was used to evaluate article quality and highlight critical aspects.Scientometric analysis was employed to process the collected scientific data and assess the impact of scientific journals, articles, topics, and keywords.Lastly, SWOT analysis was applied to analyze the strengths, weaknesses, opportunities, and threats related to immersive technologies in the AEC sector.
These tools were selected to closely align with the focus of our research, providing a rigorous framework for evaluating immersive technologies in the context of BIM and collaborative processes.

Collection and Review of Sources
During the literature review, we identified trending topics, research gaps, and directions for future research.Additionally, we adopted techniques proposed by Khan et al. [9] and Wang et al. [4] to identify gaps in existing literature and gain a preliminary understanding of the current state of research.Khan's studies highlighted strengths and weaknesses in various thematic areas related to immersive technologies in the AEC sector, providing us with an approximate overview of the state of the art.Wang's study, which evaluated influential trends and methodologies in the field, helped us define keywords more precisely for our research.
The PRISMA method, summarized in Figure 3, involves three phases: identification, screening, and inclusion.We strictly followed the PRISMA protocol, discussing any deviations from the standard protocol.

Identification
During the first identification phase, an unstructured search was conducted to gathe preliminary information on the main research themes.Various portals, such as Googl Scholar, ACM Digital Library, IEEE Xplore, Scopus, Web of Science Group, ERIC, Scienc Direct, and Semantic Scholar, were used to collect relevant publications in the AEC field including immersive technologies applied to BIM.A total of 198 resources, including ar ticles, websites, peer-reviewed journals, videos, and manuals, were collected and orga nized into three areas: immersive technologies, BIM, and collaborative processes.Thi helped identify key figures in the field and gain an initial understanding of the state of th art, as well as collect relevant keywords for the subsequent structured research phase.Th collected keywords were categorized into three areas: immersive technologies, methodol ogies and concepts for design and management of BIM, and decision-making and collab orative processes.
The top 10 most influential keywords, as shown in Table 1, were determined through cross-referencing between IEC Electropedia, an online technical dictionary and encyclo pedia that provides authoritative and internationally recognized terminology, and the in itial results of unstructured research.
For the second structured research phase, Scopus, a reputable academic databas [64,65], was used.Scopus provides comprehensive coverage of high-quality peer-re viewed articles and offers access to the most recent publications.The data analyzed in cluded journals, abstracts, types of literature, authors, keywords, institutions, and refer ences [64].The research was conducted using Boolean syntax in the Scopus search engin through the Scopus API.In this phase, the research focused solely on domains closely related to the AEC industry in order to gain a detailed focus on the current literature land scape.The analysis conducted on Scopus took into account the three areas and keyword collected in the previous phase.

Identification
During the first identification phase, an unstructured search was conducted to gather preliminary information on the main research themes.Various portals, such as Google Scholar, ACM Digital Library, IEEE Xplore, Scopus, Web of Science Group, ERIC, Science Direct, and Semantic Scholar, were used to collect relevant publications in the AEC field, including immersive technologies applied to BIM.A total of 198 resources, including articles, websites, peer-reviewed journals, videos, and manuals, were collected and organized into three areas: immersive technologies, BIM, and collaborative processes.This helped identify key figures in the field and gain an initial understanding of the state of the art, as well as collect relevant keywords for the subsequent structured research phase.The collected keywords were categorized into three areas: immersive technologies, methodologies and concepts for design and management of BIM, and decision-making and collaborative processes.
The top 10 most influential keywords, as shown in Table 1, were determined through cross-referencing between IEC Electropedia, an online technical dictionary and encyclopedia that provides authoritative and internationally recognized terminology, and the initial results of unstructured research.
For the second structured research phase, Scopus, a reputable academic database [64,65], was used.Scopus provides comprehensive coverage of high-quality peer-reviewed articles and offers access to the most recent publications.The data analyzed included journals, abstracts, types of literature, authors, keywords, institutions, and references [64].The research was conducted using Boolean syntax in the Scopus search engine through the Scopus API.In this phase, the research focused solely on domains closely related to the AEC industry in order to gain a detailed focus on the current literature landscape.The analysis conducted on Scopus took into account the three areas and keywords collected in the previous phase.

Screening
During the search and screening phases, we applied specific criteria to ensure that the selected articles and sources were directly relevant to the objective of our research.In total, 627 articles were collected, as listed in Table 2, with 198 from the unstructured preliminary research and 429 from Scopus through structured research.To improve data accuracy, filters were applied, including the time limit (2010-2023), language (English or Italian), and removal of duplicates.<<AEC OR "Architecture, Engineering and Construction" OR "Architecture" OR "Engineering" OR "Construction" AND "Immersive Technologies" OR "Immersive Realities" OR "Immersive Environments" OR "Virtual Environment" OR "Virtual Reality" OR "Augmented Reality" OR "Mixed Reality" OR "Extended Reality" OR "Metaverse" OR "Virtual model" AND "Building Information Modeling" OR "BIM" OR "Level of Detail (LOD)" OR "Blockchain" OR "AI" OR "Gaming Engine" OR "IFC" OR "Facility Management" OR "Industry 4.0" OR "Internet of Things" AND "Conferenza dei Servizi" OR "Collaboration" OR "Decision Making" OR "Decision process" OR "Remote collaboration" OR "Service conference" OR "Design review" OR "Collaborative design">> After applying these filters, 353 articles remained from the structured research and 183 from the unstructured research.At this point the articles collected were analyzed, through an in-depth study, on the basis of three key characteristics: (1) focus on BIM, immersive technologies and collaborative processes; (2) focus on sectors from the AEC industry; (3) direct application of immersive processes and technologies in the AEC industry.Each article was assigned a rating from 1 to 10 based on these characteristics.This screening process was conducted by a total of three independent reviewers, each with significant experience in the field of immersive technologies, BIM and collaborative processes in the AEC sector.To ensure interrater reliability, we used the intraclass correlation coefficient (ICC) as a statistical measure.After the independent screening phase, all the reviewers' ratings were collected in an Excel file, where each column was associated with a reviewer and the related values assigned to the articles.The ICC coefficient was calculated using MedCalc Statistical Software Version 22.014.This software allowed, once all the evaluations had been collected, to automatically calculate the coefficient, evaluating the reliability of the evaluation scale used by the three reviewers.
Figure 4 shows the report and the related estimate value of the reliability of the individual ratings equal to 0.7820, indicating high reliability between reviewers.Any disagreements were resolved through discussion and consensus among the reviewers.
Virtual Worlds 2023, 2, FOR PEER REVIEW industry.Each article was assigned a rating from 1 to 10 based on these characteri This screening process was conducted by a total of three independent reviewers, each significant experience in the field of immersive technologies, BIM and collaborative cesses in the AEC sector.To ensure interrater reliability, we used the intraclass correl coefficient (ICC) as a statistical measure.After the independent screening phase, a reviewers' ratings were collected in an Excel file, where each column was associated a reviewer and the related values assigned to the articles.The ICC coefficient was c lated using MedCalc Statistical Software Version 22.014.This software allowed, on the evaluations had been collected, to automatically calculate the coefficient, evalu the reliability of the evaluation scale used by the three reviewers.
Figure 4 shows the report and the related estimate value of the reliability of the vidual ratings equal to 0.7820, indicating high reliability between reviewers.Any greements were resolved through discussion and consensus among the reviewers.After this phase, the articles found suitable were analyzed through an in-depth s of the keywords using the VOS Viewer Software Version 1.6.19.0, which led to the e sion of articles that were not focused entirely or partially on immersive technologies, and decision-making processes collaborative.At the end of this phase, 36 articles me the criteria structured by the authors were selected.

Included
At this point once the source collection and review phase with the PRISMA pro is concluded, to develop a more impartial and precise understanding of authorship i field of data sharing for BIM collaborative processes in immersive environments w the sector AEC, the 36 articles were reanalyzed through a scientometric and SWOT ysis, in the subsequent phases four and five.This global approach allowed us to inv gate and refine current limitations and gaps in the literature, ultimately formulatin search themes and proposing concrete solutions for future developments.

Scientometric Analysis
In alignment with the overall objective of the study, which is to assess the cu state of integration between collaborative processes, immersive technologies, and this section employs scientometric analysis to evaluate the impact and interconnect of research in these domains.This analysis resolved subjectivity issues among variou erature sources.Software tools such as VOS-Viewer, CiteSpace, and BibExce After this phase, the articles found suitable were analyzed through an in-depth study of the keywords using the VOS Viewer Software Version 1.6.19.0, which led to the exclusion of articles that were not focused entirely or partially on immersive technologies, BIM and decision-making processes collaborative.At the end of this phase, 36 articles meeting the criteria structured by the authors were selected.

Included
At this point once the source collection and review phase with the PRISMA protocol is concluded, to develop a more impartial and precise understanding of authorship in the field of data sharing for BIM collaborative processes in immersive environments within the sector AEC, the 36 articles were reanalyzed through a scientometric and SWOT analysis, in the subsequent phases four and five.This global approach allowed us to investigate and refine current limitations and gaps in the literature, ultimately formulating research themes and proposing concrete solutions for future developments.

Scientometric Analysis
In alignment with the overall objective of the study, which is to assess the current state of integration between collaborative processes, immersive technologies, and BIM, this section employs scientometric analysis to evaluate the impact and interconnectivity of research in these domains.This analysis resolved subjectivity issues among various literature sources.Software tools such as VOS-Viewer, CiteSpace, and BibExcel are commonly used for conducting scientometric analyses in the AEC field [13].Following the screening phase, the results were exported from EndNote 20 in (.ris) format and subjected to bibliographic analysis using a dataset on collaborative processes integrated with immersive technologies and BIM.VOS-Viewer software was used to analyze the data, configuring the analysis for keyword co-occurrences.
The resulting keyword map shows the most important terms in the analyzed literature.Figure 5 indicates an overlay view, in Figure 6 the color of the words denotes their similarity, and Figure 7 with the color gradient indicates the publication period.
clusters.Keyword co-occurrence helps create a mental map of research themes in the field, highlighting gaps and suggesting potential future study areas.This visual tool allowed us to identify search clusters and relationships between keywords, thus contributing to the objective of the study by clarifying the thematic focuses in this research domain.VOS-Viewer generated a co-occurrence map of keywords in the integrated study of collaborative processes, immersive technologies, and BIM.
The viewer generated a keyword map, as illustrated in Figure 6.From this result, important considerations emerge.Firstly, there is a strong connection between the three research areas and the thematic areas developed by the word network.It is evident that VR, AR, decision-making, and BIM are the most significant points, as indicated by their larger sizes.Furthermore, the importance of Artificial Intelligence is growing in the AEC industry, ranking fifth in total number of connections (Table 3).Finally, the size of the circles represents the weight in the word in the network, and the distance between keywords indicates a correlation based on co-occurrence.This map aids researchers in identifying relationships between keywords and identifying research clusters.Keyword co-occurrence helps create a mental map of research themes in the field, highlighting gaps and suggesting potential future study areas.This visual tool allowed us to identify search clusters and relationships between keywords, thus contributing to the objective of the study by clarifying the thematic focuses in this research domain.VOS-Viewer generated a co-occurrence map of keywords in the integrated study of collaborative processes, immersive technologies, and BIM.
The viewer generated a keyword map, as illustrated in Figure 6.From this result, important considerations emerge.Firstly, there is a strong connection between the three research areas and the thematic areas developed by the word network.It is evident that VR, AR, decision-making, and BIM are the most significant points, as indicated by their larger sizes.Furthermore, the importance of Artificial Intelligence is growing in the AEC industry, ranking fifth in total number of connections (Table 3).
From this first analysis, starting from right to left, we can make some considerations.Regarding BIM, it can be noted that the connections with VR, AR, and decision-making processes are present but limited.It is instead more connected and closer to mixed reality.This could indicate a growing interest in the AEC industry towards the adoption of hybrid collaboration environments, which combine real and visual events.This is particularly relevant given the context of the AEC sector, which requires close integration between real and digital information.Despite this, the mixed reality cluster is still very limited compared to other, more consolidated clusters.This may be due to the fact that mixed reality is one of the most recent immersive technologies introduced.Furthermore, the integration of BIM with immersive technologies is still in the initial phase, which suggests that it may be difficult to structure and use such technologies within the standardized information processes of BIM.This difficulty may stem from the lack of information structures with standard requirements and classes that clearly define how to apply immersive technologies in BIM processes.On the other hand, for standard digital processes in BIM, concepts such as "Level of Development" (LOD) and the more recent "Level of Information Need" according to the UNI EN 17412-1 standard have already been developed.These provide clear guidance for both researchers and professionals.This is also well highlighted by our keyword network, where one can clearly see how BIM is very close and well connected to information management, collaborative design, and so on.A similar information structure could be defined for immersive technologies as well.Another issue that could justify this current detachment highlighted by the word network concerns the reliability of the results obtained in immersive environments, as highlighted by Bernal et al. [66].It is essential to pay attention to the type of immersive scenario one wishes to simulate, the immersive aspects one intends to use, and the final level of immersiveness desired.
As for BIM, its limited connection and detachment could also be attributed to the technological challenges and specialized skills required to use such technologies.Indeed, the use of such technologies can be costly during the phases of the collaborative process and requires specialized figures.
In the central part, we note that VR represents the largest and most well-connected cluster, including AR, which is a more recent technology.The decision-making cluster is also closer to VR, which could indicate a growing interest in the AEC industry for virtual collaboration environments, but could also be due to the longer presence of such technology in the market.Furthermore, this interest may be fueled by the recent regulatory framework and standards on the application of immersive technologies, which clarify how information exchange should occur in tools between the real world, the virtual world, and the worlds of mixed reality (ISO IEC 25003 [67] and IEEE 2888 [68]).Moving towards the right, we also find AI, but it is at some distance from the others, perhaps due to its recent evolution and not easy applicability in the context.

SWOT Analysis
The SWOT analysis is a widely recognized tool for strategic planning and is employed in this study to examine and understand the strengths, weaknesses, opportunities, and threats of a specific context [13].After identifying 36 articles through a review and categorization process, based on the PRISMA Protocol and scientometric analysis, in line with the specific objective of this study, the SWOT Analysis was used to scrutinize the strengths, weaknesses, opportunities, and threats in the application of collaborative processes in the AEC sector across four key domains: Synchronization, Interaction, Decision-making Process, and Validation.These domains were constructed based on the current definition of collaborative processes in the literature [53,69,70] to provide a solid foundation for subsequent analyses.
To further clarify the methodology, each article was analyzed using a standardized SWOT model that included predefined categories and subcategories derived from the literature.This model was employed to systematically evaluate each article based on its contributions and limitations within the four domains.
Each of the 36 articles was carefully read and coded by three reviewers.Every reviewer read and coded the article, focusing on the four key areas.For each article, we assessed the presence and depth of the four key domains: Synchronization, Interaction, Decision-making Process, and Validation.Based on these criteria, we then classified the attention given to each domain into two groups, "Not Addressed" or "Addressed".Finally, all the results were summarized in Table 4, which presents an overview of the depth with which each article addresses the four key domains, according to the classification scale we developed.

Results
In line with the main objective of this study, which is to provide a solid reference point for future research development and improve understanding on the importance of defining specific levels of information for the effective use of immersive technologies , in this section the results are presented in table form.The breakdown of each of the four main domains into more detailed levels, as seen in Figure 8, based on the definition of collaborative processes expressed in the literature [69], such as information gathering and data access, information communication and formulation of ideas, data inspection and selection, check and approval, has allowed for a better definition of specific research areas and a more structured and detailed SWOT analysis.x x 11 [9] x x 12 [10] x x 13 [77] x x 14 [54] x x 15 [78] x x 16 [53] x x 17 [51] x x 18 [79] x x 19 [80] x x 20 [81] x x 21 [82] x x 22 [83] x x 23 [84] x x 24 [85] x x 25 [86] x x 26 [38] x x 27 [87] x x 28 [88] x x 29 [52] x x 30 [89] x x 31 [11] x x 32 [90] x x 33 [91] x x 34 [92] x x 35 [93] x x 36 [94] x x

Results
In line with the main objective of this study, which is to provide a solid reference point for future research development and improve understanding on the importance of defining specific levels of information for the effective use of immersive technologies , in this section the results are presented in table form.The breakdown of each of the four main domains into more detailed levels, as seen in Figure 8, based on the definition of collaborative processes expressed in the literature [69], such as information gathering and data access, information communication and formulation of ideas, data inspection and selection, check and approval, has allowed for a better definition of specific research areas and a more structured and detailed SWOT analysis.As shown in Table 4, none of the 36 articles examined provide a comprehensive framework for the selection of data and information when using immersive technologies in collaborative processes employing BIM methodology.Most articles focus on initial phases or isolated aspects of the process, such as data collection or visualization.However, there is a lack of a holistic approach that integrates these elements to achieve a certain level of immersive maturity.
In this regard, the SWOT analysis has revealed some significant strengths.For instance, an effective definition of immersive requirements and prerequisites can facilitate synchronization and interaction during the use of immersive technologies.This is crucial for reducing the production of redundant data and improving process efficiency.
The formulation of effective information processes allows for quick and clear communication between the real and virtual worlds, as well as from virtual to virtual.This not only facilitates interdisciplinary collaboration but also reduces the time required for information transfer.From a decision-making standpoint, the proper setting of requirements and prerequisites provides the opportunity to inspect data and select relevant information.This limits the sense of loss for users in virtual worlds and improves information management.Additionally, a well-structured information flow enables effective validation of projects and models in immersive environments, opening new opportunities beyond traditional validation methods.
However, there are also weaknesses to consider.For example, synchronization may be hindered by the difficulty of setting up information procedures with clear requirements due to the variability of subjectivity among users.Interaction also presents challenges, such as the difficulty of standardizing requirements due to the need for multiple exchange flows between virtual worlds.From a decision-making perspective, the absence of deep awareness in the early stages can lead to incorrect or ineffective decisions.Lastly, the validation phase can be time-consuming and resource-intensive due to the need for continuous monitoring of the standards required for the virtual part.
Despite these weaknesses, there are several opportunities.Planning requirements for the use and access to information with immersive technologies could facilitate information management and encourage greater adoption in the sector.Well-structured guidelines and requirements could accelerate exchange flows, offering new opportunities for innovation.Moreover, well-defined requirements and prerequisites could improve the quality of decisions made.This also allows the possibility of conducting evaluations and validations based on sensory perception, providing a more comprehensive framework for project assessment and validation.
Finally, there are also significant threats that need to be addressed.The difficulty of defining clear immersive requirements, the rapid evolution of technology, and the subjectivity of the immersive experience are persistent issues.Interaction between multiple users and virtual worlds could lead to data overcrowding, complicating information management.Errors in the configuration of the virtual world can negatively impact decisions, and an offering of immersive information that does not meet expectations could limit the effectiveness of technologies in the validation phase.Moreover, this can create disparities with the rest of the market, with the possibility of coming into contact with a too narrow circle of providers that meet the requirements.
Table 5 provides a comprehensive critical review of each domain, shedding light on how these areas contribute to or hinder the achievement of the main objective of this study.This overall analysis has allowed us to assess strengths, challenges, opportunities, and threats, formulating a research question in line with the current state of the art.

Decision Making
With the correct setting of requirements and prerequisites, we have the ability to inspect data and select information, limiting users' sense of loss within virtual worlds and improving information management.
A deep awareness of objectives is needed from the earliest stages.Lack of this awareness can lead to wrong or ineffective decisions.
The presence of immersive requirements and prerequisites allows users to immediately know the possibilities.This could improve the quality of decisions made.
Incorrect configuration or manipulation of the virtual world can affect final decisions.This could lead to conflicts and inefficiencies in the decision-making process.

Validation
A proper flow of information, even in immersive contexts, enables users to assess the use of immersive technologies in project control and validation practices.This opens new opportunities for project validation in virtual environments, in addition to traditional digital ones.
Increase in energy expenditure due to the need for continuous monitoring of standards.This can be burdensome in terms of time and resources.
The ability to conduct evaluations and validations based on sensory perception as well.This could provide a more comprehensive framework for project evaluation and validation.
A discretionary level of immersive requirements could lead to an offering of immersive information that may not meet expectations.
This could limit the effectiveness of immersive technologies in the validation phase as it creates a disparity with the rest of the market, exposing one to a too narrow circle of providers who meet the requirements.

Discussion
In this research, we conducted an in-depth analysis of the literature to explore the challenges and opportunities associated with the widespread adoption of immersive technologies, with a particular focus on collaborative processes within the BIM methodology.Our research identified current gaps through an integrated approach of comprehensive review and detailed, specific analysis.This study was divided into three main thematic areas: BIM, Immersivity, and Collaborative Process.These topic areas were selected to directly address our research goal of improving understanding and facilitating the adoption of immersive technologies in the AEC industry.
During this analysis, we identified the lack of a well-defined information structure for immersive technologies, especially when it comes to highly interactive applications such as decision-making and validation processes within BIM contexts.
The current literature does not seem to provide clear guidance for classifying the requirements and prerequisites of immersive information, in contrast to the well-defined traditional information flow within the BIM methodology, as outlined by the recent UNI EN 17412-1 standard, which defines the "Level of Information Need".The absence of a defined information structure for immersive information from our analysis appears to be a barrier to the full integration of immersive technologies into collaborative BIM processes.
The following research questions and subquestions constitute an important extension of our main objective and will guide future research: "How does the use of immersive technologies in collaborative processes with BIM methodology require specific information and/or data to be correctly applied?" From this main question that emerged following the analyses conducted, three subquestions have also been structured: 1.
What information and/or data are required to correctly apply immersive technologies in combination with BIM methodology?2.
Is there a specific "Level of Immersion Requirements" for these applications?3.
If so, how is this "Level of Immersion Requirements" defined and applied?
The improvement and integration of informational processes in Building Information Modeling (BIM) through the use of immersive technologies represent crucial objectives that go beyond traditional activities of data collection, analysis, manipulation, and distribution.A particularly relevant sphere is the integration of well-structured informational flows that allow for the incorporation of immersive technologies, especially in collaborative environments already employing BIM methodology.The opportunities and challenges associated with such innovations are essential for progressing towards our primary objective.In this scenario, some elements are directly related to research questions and serve both to highlight the potential benefits offered by immersive technologies and to identify areas that require further improvements for easier integration into BIM-based collaborative processes.Within the context of this research, several key issues emerge: 1.
Information Requirements for Immersive Technologies in BIM Methodology: The main question investigates how the use of immersive technologies in collaborative processes with BIM methodology requires specific information and/or data for correct application.Different processes, not only digital ones, can offer various methods for calculating, analyzing, and perceiving data.This variety is crucial for defining and applying the 'Required Level of Immersion'.This point can explore what information and/or data are necessary for the correct application of immersive technologies in combination with BIM methodology, thus answering sub-question 1.

2.
Definition of the Required Level of Immersion: This point could examine whether there is a specific 'Level of Immersion Requirements' for these applications, as indicated in sub-question 2, and how this level is related to the variety and complexity of the processes involved.

3.
Application of the Required Level of Immersion: Here, the focus could be on how the 'Level of Immersion Requirements' is defined and applied in practice within the context of collaborative processes using immersive technologies and BIM methodology, as indicated in sub-question 3.
However, it is essential to consider several limitations that may affect the validity and applicability of the results.One of these concerns the literature review, where the collection of both structured and unstructured information may not have considered some relevant sources or research.Furthermore, it is important to recognize that the challenges associated with the adoption of immersive technologies in the AEC industry can vary significantly based on geographic, cultural, and industry-specific factors.The recommendations and strategies identified may not be directly applicable to all contexts.Additionally, the need for further future research should be highlighted.While research can identify gaps to be filled, it is important to note that it may not provide concrete solutions.The development and implementation of the necessary frameworks to address these challenges may require considerable time and resources.Finally, it is essential to consider the specificity of the AEC industry.This sector is highly specialized, with unique characteristics and requirements.It is important to recognize these limitations, as they provide context for our primary objective and suggest areas for future research.

Conclusions
The conclusions drawn in this study contribute significantly to achieving our main objective by identifying key areas for future research.In particular, this research revealed a significant gap in the literature regarding the integration and identification of an "Immersive Need Level".This lack proved to be a crucial challenge, highlighting the need for further investigations to develop a solid theoretical framework in this area.Furthermore, the results suggest that the implementation of a structure with immersive prerequisites and requirements could pave the way for significant improvements in the AEC industry, enhancing process accuracy and promoting broader adoption of immersive technologies.While this article strives to offer a comprehensive overview of the current state of research and suggest directions for future work, it is understood that the field is continuously evolving.The systematic review provided aims to serve as a resource for stakeholders, professionals, and researchers in the AEC industry.It offers insights into both current practices and potential future developments in creating an immersive requirements framework for collaborative processes with BIM.Given the specific nature of the research topic, future studies could expand upon this work by exploring additional contexts, utilizing different keyword combinations, and consulting a broader range of evidence sources.

Figure 1 .
Figure 1.Scheme of Immersive Technologies divided by key concepts and areas for AEC industry.

Figure 1 .
Figure 1.Scheme of Immersive Technologies divided by key concepts and areas for AEC industry.

Figure 4 .
Figure 4. Final report obtained with MedCalc Statistical Software.

Figure 4 .
Figure 4. Final report obtained with MedCalc Statistical Software.

Figure 6 .
Figure 6.VOSviewer network visualization with subdivision based on the clusters it belongs to.

Figure 6 .
Figure 6.VOSviewer network visualization with subdivision based on the clusters it belongs to.

Figure 7 .
Figure 7. VOSviewer Overlay visualization based on year of publication.

Figure 7 .
Figure 7. VOSviewer Overlay visualization based on year of publication.

Figure 8 .
Figure 8. Hierarchical pyramid of domains according to collaborative processes for the AEC sector.Figure 8. Hierarchical pyramid of domains according to collaborative processes for the AEC sector.

Figure 8 .
Figure 8. Hierarchical pyramid of domains according to collaborative processes for the AEC sector.Figure 8. Hierarchical pyramid of domains according to collaborative processes for the AEC sector.

Table 2 .
Total documents analyzed and grouped by scope.

Table 3 .
Descending list of top 20 keywords and their Weights-Link, Total Link Strength and Weight-Occurrences.

Table 4 .
The 36 articles sorted for each domain and scaled based on the depth of the collaboration process achieved with immersive technologies.