1. Introduction
Advances in information and communication technologies provide opportunities for Architecture, Engineering, and Construction (AEC) professionals to collaborate remotely. These technologies support collaboration in distributed teams and save the travel time to meetings for face-to-face interaction. Construction projects require the coordination of different AEC disciplines with complex representations of design and analysis. In general, AEC project stakeholders use Building Information Modelling (BIM) at different phases of a facility’s life cycle to insert, extract, update, or modify information to support and reflect the stakeholders’ roles [
1]. With effective collaboration and management strategies, BIM brings value to construction projects by reducing the field interferences, increasing productivity, reducing rework, requests for information (RFIs), change orders, and cost growth [
2]. In particular, the 3D coordination process that begins from the design phase and is carried out through the construction phase accomplishes this value by enabling the project team to resolve the field conflicts before installation [
2,
3]. This process requires the multidisciplinary collaboration of the designers and builders, both the exchange of models as well as discussion and negotiation around how these disciplines intersect. Per our prior observational studies, typically the critical building system conflicts that require different project stakeholders’ involvement to be resolved are discussed in 3D coordination meetings. The rest of the system conflicts are coordinated asynchronously [
4].
Research has shown that while BIM tools support problem definition, the support for team members’ dialogues to brainstorm and create shared knowledge to resolve problems and make decisions is less clear [
5]. To brainstorm and collaborate, AEC team members draw, write, sketch, or talk together [
5]. In common practice in the 2010s, BIM-based remote 3D coordination meetings, BIM was shared synchronously on a 2D shared screen where only one person has control over the view and the pointer and can create markup on the model. This made team engagement and collaboration more challenging than face-to-face meetings, where team members could discuss through pointing and sketching together. To create annotations in the asynchronous 3D coordination process, AEC professionals draw markup and add comments as texts on the 2D screenshot of the 3D model. This brought some limitations in terms of communication, as the snapshot may not capture all the required digital information [
4].
The AEC industry has recently seen a growth in the use of innovative technologies, including Extended Realty (XR), which is an umbrella term for technologies like Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality [
6]. Despite AR and MR that present the digital content in the physical environment, VR provides a digital world that makes it a practical tool for remote collaboration. Unlike BIM, which presents 3D models on 2D screens, VR provides an environment for the user to be immersed in the model. The immersive VR experience can be created with a head-mounted display (HMD) or projected systems where the model is projected on a curved screen or the sides of a large cube [
7]. In recent years, HMD hardware has become more affordable and available for individual use in the market, while projected VR systems are expensive and require a large space to install, and are time-consuming to maintain. Projected VR systems also require the project teams to meet physically. This makes the use of HMD preferable for the industry and a practical tool for remote collaboration. Unlike BIM software packages where features are already defined within the program, VR content can be created in gaming engines like Unity [
8], that allows the creators to add customized features to the interface. Some VR systems enable the users to share the virtual space and draw together in a 360-degree environment. In asynchronous collaboration, some VR systems allow users to record messages with voice while using the markup tool to draw to explain system conflicts and resolutions. In this case, the user who receives the message can still explore the model while the markup is being created in the recording. As compared to typical BIM interfaces, the VR markup in these systems is dynamic while BIM’s is fixed on the 2D screenshot of the model and disappears when the user wants to explore the model. While there is renewed interest in using VR for remote collaboration, there remain questions about how this technology can support technical collaboration in design and construction teams such as 3D Coordination.
The studies on VR for AEC collaboration are mainly conducted on design review, a process that starts from the planning phase and ends before the start of the construction [
2], which does not necessarily require the construction team’s involvement. These studies have a focus on the end-user experience or communication of the design by professionals with non-technical clients [
9,
10,
11,
12,
13,
14,
15,
16,
17]. Sateei et al. (2022) recently conducted a study in which HMD was utilized for the architectural design review of a school project. The users were given tools to create markup, measure dimension, and take snapshots in VR. The participants found these tools helpful in collaborating and understanding each other’s point of view and spatial reasoning [
18]. In a research study, VR’s application for 3D coordination was explored, where the Mechanical, Electrical, and Piping (MEP) system review was led by a BIM modeler and an MEP installer using HMD. In this study, the virtual model was explored to check pipeline conditions, clashes between MEP and architectural and structural systems, the installation process, and the adequacy of space for equipment maintenance. The participants had positive feedback on using VR for 3D Coordination and suggested adding a markup tool to the VR interface to make it more practical [
19]. In a research study conducted with avatar-based desktop VR enabled with markup tool, teams had more mutual discoveries of design issues in VR in comparison to BIM. In this study, project participants collaborated in remote virtual meetings, where globally distributed architecture and construction teams were tasked to perform design review. Teams could draw markup together to convey their thoughts and highlight design problems. However, the virtual team setting was similar to BIM-based practices, where markup was created on a 2D screenshot of the model [
20]. From this prior research VR supports the creation of shared understanding and is an effective method to convey technical information across a diverse group of people. What is not yet understood is how markup tools in the 3D coordination processes effect multidisciplinary AEC team collaboration efficiency.
In this study, to measure the team’s collaboration efficiency, a psychological method called Shared Understanding was utilized. Team members represent the understanding of their environment in the form of Mental Models. Mental Model elicitation methods capture the research-related concepts and their relationship in the individual Mental Model [
21]. The shared concepts and links among the team members’ Mental Model structures represent Shared Mental Model or Shared Understanding [
22]. Shared Understanding in the context of AEC collaboration is the phenomenon where team members have a mutual understanding of the disciplinary requirements and constraints to discuss design options and make decisions [
23]. The common Mental Model elicitation methods used in psychology are observation, questionnaires, interview, content analysis, and card sorting [
21,
23]. Mental Models were studied in the AEC industry in the design teams, that included engineering and architecture design creativity [
24] and Shared Understanding between the architects and clients [
25]. In this study, we focused on Shared Understanding between the designers and builders. We designed this research project to study the effects of VR’s immersive environment and markup tool capabilities on the multidisciplinary AEC team’s Shared Understanding in the remote 3D coordination processes.
Background
Drawings are traditionally created using Computer-Aided Drafting (CAD) software that automates the manual drafting process. The trade coordination process is then performed by sequentially comparing transparent drawings for each system generated from CAD over a light table to find the conflicts between different building systems. This process requires frequent meetings. Visualizing complex building systems in this method is difficult, and accommodating design changes are challenging [
26]. Due to the inefficiency of this process, numerous conflicts often remain undetected and must be addressed in the field, which is costly [
27]. With the introduction of BIM to the AEC industry, teams spend less time in coordination meetings using BIM compared to the paper-based processes and have more satisfying coordination processes [
27,
28]. In the 3D coordination processes using BIM, the authoring software creates scaled, parametric, and object-oriented 3D models for building systems [
29]. BIM review software combines different building system models into a single model, called the federated model, and determines the conflicts between the systems using the clash detective tool by comparing their 3D models [
3,
30]. Although BIM has facilitated the 3D Coordination processes by automating the detection of clashes between building systems, it requires the AEC project stakeholders to collaborate and resolve them [
31].
In the last two decades, the use of VR for collaboration has increased in the AEC industry. VR is a technology that can simulate the reality human beings experience. It’s a computer-generated environment that can give the user an illusion of being in a virtual world. Power wall and CAVE are projected-base VR technology where the model is projected on large screens. In power wall, large screens are set in a way that they create a curved screen. In CAVE, model is projected on the walls of the room-sized cube [
7]. Researchers have used these technologies for face-to-face team collaboration on the design review of university facilities [
9], hospital patient rooms [
10], and courtrooms [
11,
12] as well as scheduling of a nuclear power plant [
13]. Liu et al. (2020) conducted a research study on thirteen design review meetings where various visualization media like 2D drawings, BIMs, and renderings supported the team collaboration in projected VR [
17]. Research studies with HMD has been mainly focused on single users with no team interactions. A limited number of studies has focused on multi-user HMD VR that includes the design review of university facilities [
14,
15], residential and commercial buildings [
16], and a school [
18], as well as design review and 3D Coordination of an office building [
19] and scheduling of various construction projects [
32]. Truong et al. (2021) studied remote VR collaboration for the construction planning of elevator machine rooms. Users were equipped with tools such as free hand drawing, cube drawing, measuring tool, and camera. Participants were asked to identify the installation challenges, use the free hand drawing tool to mark them up, and then capture the VR scenes with the camera tool. Participants reported utilizing multi-user VR system to be preferred over teleconferencing for collaboration [
33]. Markup tool was used in only two of these studies on the AEC team collaboration in the multi-user VR platform [
18,
33].
The 3D Coordination processes require the AEC project stakeholders to collaborate and resolve the conflicts between the building systems by exchanging disciplinary knowledge while they vet design alternatives. Project team members have in-depth knowledge in the areas of their expertise, but they share a part of their knowledge understandable by other team members in explaining design ideas, disciplinary constraints, and technical analysis to collaborate, find solutions, and make decisions. This phenomenon is referred to as Shared Understanding. Prior studies suggest that Shared Understanding is highly desirable for interdisciplinary teams as it has a positive effect on team performance [
34,
35], team member satisfaction [
34], coordination of activities among team members [
36], innovation [
37], reduction of iterative loops and rework [
38], and team morale [
39]. There remains the question of how technology tools like BIM and VR can support teams to build Shared Understanding in the 3D coordination processes.
2. Materials and Methods
To study the effects of VR’s immersive environment and markup tool capabilities on technical AEC collaboration, controlled experiments were designed to compare the markup enabled immersive VR platform with BIM, which was the control platform. Two experiments of A and B were designed to study the asynchronous and synchronous team collaboration, respectively. Experiment A was developed to study the individual’s Mental Model of technical knowledge communicated in a one-to-one asynchronous collaboration. Experiment B was designed to study Shared Understanding at a team level in synchronous collaboration. The technical information in the experiments was controlled. Study participants were provided role-specific technical information and were required to collaborate based on the given technical knowledge. To assess Shared Understanding, the research team used observation and questionnaire methods. The observation method allowed the research team to track conversations to elicit individual Mental Models and Shared Understanding. It also allowed for the study of how users utilized the markup tool and interacted with the digital interface. With the questionnaire method, the users’ immediate responses after the experiment were captured while using the interview method had some limitations in this regard. The questionnaires were designed in a way that they captured the individual’s understanding of the technical information and team decision. They also provided an opportunity for the study participants to give feedback on their experiences.
2.1. Participants
The experiment participants were twenty-four University of Washington (UW) graduate students enrolled in a graduate-level Virtual Construction course in the Department of Construction Management. In the first week of the class, students’ educational background, industry experience, and previous experience with BIM and VR were surveyed to assist in grouping them into comparable teams to reduce the effects of background experience on the results. Students’ educational backgrounds were mainly in architecture and civil engineering. The average industry work experience of the participants was three years. Six students had worked as 3D modelers in the industry. They were either exposed to some VR or did not have any previous experience. Participants were taught BIM and VR skillsets for seven weeks with a main focus on model navigation, design review and 3D coordination. During this time, teams were given a term project that required them to get to know each other, work in a team setting, and build a team relationship. Experiments A and B were given as homework and in-class activity assignments in the eighth week of the class, respectively.
2.2. Digital Setup
The digital platforms of BIM and VR were designed in a way that they provided the same features for the users except for the markup tools that were unique for each platform and immersion in VR. For the BIM platform, Autodesk Navisworks [
40] was installed on PCs and allowed users to navigate the models and review them using tools like commenting and markup. A mobile Application (App) developed by a startup company was utilized for the VR platform. The VR App offered a cloud-based virtual collaboration platform that provided a color-coded markup tool. The VR App was installed on smartphones, and the immersive VR content was viewed through glasses called Viewer attached to the smartphone. This App supported three degrees of freedom (3DOF). Meaning, it tracked the head orientation and enabled the users to look around while they were virtually fixed in one location. The users looked at a static 360-degree spherical image using the App. Autodesk Navisworks’ navigation tool provided six degrees of freedom (6DOF) to the user and allowed them to both look around and walk around inside the model. To design a controlled experiment, there was a need to set up the BIM platform in a way that it provided the same 3DOF experience in VR as for the BIM users. For this purpose, viewpoints were created in the middle of the model spaces. The viewpoint in Autodesk Navisworks is the 3D snapshot taken of the model as it displays in the screen view. The viewpoints were created from the eye level of an avatar with a height of 5 feet and 6 inches. Participants were allowed to use the navigation tool of Look Around to explore the model in the defined viewpoints and use the Review tool to create markup. The field of view in BIM review software was set to 90 degrees to replicate the same field of view in VR. The VR content was created using the Rendering tools in Autodesk Navisworks. A static 360-degree spherical photo was captured at the location of each viewpoint from the same eye level in BIM. To create a markup, users should have touched the smartphone screen and drew by head movement. If the cellphone screen remained untouched for a few seconds, the markup would disappear. Users could explore the model in VR by head rotation while they were required to use a computer mouse in the BIM platform to explore it on desktop. The digital setup is discussed in more detail for each experiment in their relative section.
2.3. Experiment A: Asynchronous Collaboration
Experiment A was designed to evaluate the efficiency of VR platform features in an asynchronous 3D coordination process. This experiment studied the effects of two variables of VR’s voice and dynamic markup in the 360-degree environment on one-to-one individual communications in comparison to text and markup on the 2D screenshot of the 3D model in BIM. The individuals’ understanding of the annotations created for communicating building system conflicts and resolution as well as the efficiency of the VR features for communicating the conflicts and proposing alternative design options by the study participants to other team members were evaluated. The research study was set up based on the federated model of the new Burke Museum building on the UW Seattle campus. The project’s general contractor, Skanska, provided this model for educational and research purposes to the research team. The building’s mechanical room was selected as the experiment space, which had complex MEP systems.
2.3.1. Scenarios
Two scenarios of A and B were designed for this experiment. In Scenario A, the study participants received the digital files in both BIM and VR platforms in which a conflict of building systems and the resolution were described. In the second scenario, the study participants were asked to create markups and communicate another system conflict and the resolution using BIM and VR features.
Scenario A
In the first scenario, the structural engineer increased the depth of two structural beams which caused clashes with the pipelines passing underneath. The BIM manager informed the piping subcontractor to revise the model by dropping pipelines down based on the mechanical engineer’s recommendation. The first beam, called Beam 1, clashed with two branches of hot water pipelines. The piping subcontractor should drop the main hot water pipes along with the branches eight inches down to prevent the system conflict. The second beam, called Beam 2, clashed with a group of pipelines, including the main hot water pipelines, whose branches clashes with Beam 1. The piping subcontractor should drop down the group of pipelines resting on the hanger for six inches, while the main hot water line should still be dropped eight inches due to the clash with Beam 1. The structural beams were located in two different parts of the mechanical room. A location relatively close to both clash groups was designated in the model. When fixed in this location facing one clash group, the user needed to turn around approximately 90 degrees to see the other clash group. These clash groups are shown in
Figure 1. In this figure, the clash group of Beam 1 with the pipeline is called Clash 1, and the clash group of Beam 2 with the pipeline is called Clash 2.
Scenario B
In the second scenario, Beam 2 clashed with the mechanical ductwork. Participants were asked to take the BIM Manager’s role and create annotations in both platforms of BIM and VR to explain the cause of this clash to the mechanical subcontractor. Then, point out the ductwork’s bend in another location in the model and ask the subcontractor to resolve the clash by dropping the duct further at the bend.
Figure 1 shows the location of the duct’s bend and the clash of the duct with Beam 2, which is called Clash 3. Participants needed to turn around approximately 150 degrees in the model to see the location of the duct bend when facing the clash.
2.3.2. Digital Setup
To communicate the cause of the clash groups, their relevance to each other, and the required action for resolving the clashes in the BIM platform, two viewpoints were created in the BIM platform for clashes 1 and 2. Participants could click on each of the viewpoints in Saved Viewpoints window to see the annotations. The explanation was given as text in the Autodesk Navisworks’ Comments section, and the model was marked up using its Review tool. The markup’s color was selected to be cyan to match the VR App’s default color code. Since annotations were created on a 2D snapshot of the model, if participants moved in the model using navigation tools, the annotation would disappear. To see the annotations again, they had to click on the saved viewpoints.
Figure 1 shows the expanded 360-degree spherical photo captured from the same location and eye level in BIM, and
Figure 2 shows the annotations created in two viewpoints in the BIM interface. In the VR platform, a cloud-based message was recorded in which the same explanations typed in the Autodesk Navisworks’ Comments section were communicated by voice while a dynamic markup was created highlighting system conflicts and resolutions as the explanation was provided. The markup drawings were the same as the ones created in the BIM platform.
Figure 3 provides snapshots of the recorded message in VR. The study participants could explore the model in the 360-degree environment while receiving the message. There was a need to guide them in the environment to know in which direction they should look to see the markup. For this purpose, the message asked them to look at the dialogue box in the VR interface, and they were then guided with markups from there.
2.3.3. Procedure
Study participants were divided into two groups named BV and VB based on the sequence to which they were exposed to the models. For instance, Group BV was asked to check the annotations in the BIM platform first and then switch to VR. Each participant had received a BIM file and a meeting ID for the VR App to explore the annotations related to the conflict of structural beams with pipelines. They were then asked to compare the annotations in two platforms and explain which one they preferred to understand the building system conflicts and resolution. In the second part of the experiment, participants created annotations in both platforms based on the sequence defined by their Group name to communicate the clash of the duct with beam and its resolution to the mechanical subcontractor. They used the same BIM file to create viewpoints and markups. In the VR platform, they recorded their message by replying back to the message they originally have received in the VR App. Participants were then asked to give feedback on their experience and the preferred platform features that supported their technical communication.
Figure 4 presents the procedure schematically.
2.4. Experiment B: Synchronous Collaboration
The Experiment B design was based on the collaboration of four team members with different AEC roles of the architect, structural engineer, mechanical subcontractor, and piping subcontractor. Two comparable scenarios were created in which the structural design changes were affecting the scope of other disciplines in the project. Team members were asked to exchange disciplinary knowledge to find an alternative design option to accommodate the structural design changes. Teams had the opportunity to work in both BIM and VR platforms. The disciplinary information was provided to each team member based on their specific role in the team for the purpose of controlling the exchanged knowledge content. To evaluate individual’s understanding of the exchanged disciplinary knowledge and team decision, or in other terms Mental Model concepts, questionnaires were designed and given to the participants at the end of the meeting in each platform. Participants were asked to fill out another questionnaire at the end of the experiment to reflect on their experience in two platforms. The 3D coordination meetings were video recorded for the observational study purpose. Since facial expressions was not captured in VR, participants were prohibited from sharing videos and were only allowed to communicate with voice.
2.4.1. Scenarios
Two comparable scenarios with the same number and type of technical constraints were designed based on a hypothetical research facility where mechanical and piping equipment in the mechanical room serve the laboratories (Labs). In the first scenario, Scenario A, the mechanical room, and the Labs are located on the same floor where the duct and pipes run horizontally. In the second scenario, Scenario B, the mechanical room, and the Labs are located at two different levels, and the duct and pipes run vertically. The details of both scenarios are as follows.
Scenario A
In the first scenario, a part of the southern zone of the research facility was presented to the participants, as seen in
Figure 5a. One air handler and two boilers located in the mechanical room serve Lab B on the east side of the plan. The duct and the pipes exit the mechanical room and enter the East corridor, which has a ceiling soffit to embed the duct and pipes. They enter Lab B from the North corridor. The structural engineer is assigned to inform the team that the East wall of the mechanical room and the Lab office with the total length of 40 ft needs to be a shear wall based on the structural analysis. As a result, the opening area in this wall should be limited. Otherwise, a structural failure could happen. In the original design, there are three openings in the wall: one for the door, one for the duct, and one for two pipes. The opening area should be limited to only one opening, either for one duct or two pipes, and the door needs to be relocated. To relocate the mechanical room door, the architect notes that it can be located on the West wall to use the West corridor. The door has to be located in either the corners or middle of the West wall of the mechanical room right behind one of the boilers or the air handler. The architect also informs the team that the Lab office was previously designed as a storage room. As a result, no ceiling soffit was considered for this room. The owner does not want to pay for the ceiling soffit. If the subcontractors want to route the duct and pipes through the Lab office, a corner soffit needs to be installed, which is cheaper than the ceiling soffit. Each corner soffit can embed either one duct or two pipes and should be along the East or West wall of the Lab office. The cost for the 20 ft corner soffit is USD 1500 for two pipes and USD 2000 for a duct. The mechanical subcontractor warns the team that due to the sensitivity of Lab A to vibration, no MEP system should be placed in the West corridor. Based on the mechanical subcontractor’s conversation with the mechanical engineer, by moving the air handler to the East wall and routing it from the East corridor, they needed to spend an extra USD 2000 to buy a more powerful air handler since it needs to push the air through two consequent duct bends. The piping subcontractor reminded the team that the ceiling height is low. As a result, the duct and the pipe could not be installed at different heights. No piping or ductwork could go above the door. If the subcontractors changed their routing, they needed to make sure the duct route ended at the same point where the current duct and pipe were in the Lab. The ductwork and piping cost USD 50/ft and USD 25/ft, respectively. Subcontractors could only use 90 degrees bends. They should also consider maintenance areas for their equipment providing approximately 10 feet of clearance. Meaning if they line all equipment on one wall, two pieces of equipment should be located at the corners and one in the middle of the wall. The architect prefers to have both the boilers and the air handling unit on one wall of the mechanical room so that the owner can use the rest of the room space for storage since the storage room was turned into the Lab office. The owner preferred to spend less than USD 2000 on all the changes the team makes to the design.
Scenario B
In Scenario B, another zone of the research facility was presented to the experiment participants, as seen in
Figure 5b. The mechanical room and the storage room were located on the first floor, and the Lab and the Lab office were on the second floor. The structural engineer was assigned to inform the team that the Lab on the second floor had heavy equipment, which results in a high shear force applied to the slab underneath. During the design review process, the structural team had realized the two slab openings provided by the mechanical and piping subcontractor for the pipe and duct risers in the Lab floor slab would result in structural failure. By pouring a thicker concrete slab, the structural engineer could allow one opening in this slab for either one duct or two pipes. Pouring a thicker slab would result in a USD 2000 extra cost based on the conversation with the general contractor. The slab below the Lab office on the second floor could have a maximum of two openings, one opening for one duct, and one opening for two pipes. A large opening for both the duct and two pipes would result in structural failure. The architect did not prefer the MEP routing to be seen in the Lab office, but it could be seen in the storage room. The architect preferred to have the openings in the slab on the corners of one wall so that the MEP system could be embedded in the corners of a wall-to-wall cabinet. The owner had already accepted paying for the cabinet in the Lab office, but the location of this cabinet was not specified yet. If the team decides to embed the MEP system in the cabinet, some cabinet space would be occupied that could not be used. The team needed to consider USD 500 extra cost for embedding one duct or two pipes in the corner cabinets for installation and occupying the usable space. The architect preferred to have both the boilers and the air handler on one wall of the mechanical room so that the owner could use the rest of the room space for storage. Since one storage room became a Lab office, as explained in Scenario A, the owner needed to use the mechanical room space for storage. Adding a duct bend to the current route results in USD 500 extra cost. The same constraints of ceiling height, routing over door, maintenance area, and routing angles are applied in Scenario B. The ductwork and piping cost USD 50/ft and USD 25/ft, respectively. The owner preferred to spend up to USD 4000 for all the changes team made to the design.
Alternative Design Options
The intended solution to accommodate the structural design changes in Scenario A was to move all the equipment to the North wall of the mechanical room, and move the door to the West wall. They could put the air handler on the Northeast corner and route the duct from the East corridor and route the pipes from the soffit. Another acceptable option was to put the air handler on the Northwest corner, route the duct from the Lab office and route the pipes from the East corridor or with a more expensive option route them both from the Lab office. The intended solution to accommodate the structural design changes in Scenario B was to keep the air handler in its current location, move the door to the West wall, move the boilers to the East wall and route them from the storage room and then up to the Lab office, embed them in the cabinet, and then route them into the Lab. They could also move all the equipment to the West wall, route the pipes as previously explained, and add a bend to the duct. This would cost slightly above the budget due to the extra pipe length for routing from the storage room, which was considered negligible. Participants had various options to move the equipment and reroute the piping and ductwork to meet the technical requirements of the scenarios, however, only the design alterative options explained above met the budget.
2.4.2. Questionnaires
To capture each participant’s understanding of the exchanged technical information and team’s final decision, four questionnaires were designed. The Questionnaires AA and BA were given at the start of the scenarios A and B team meetings, respectively. These questionnaires contained empty drawings of the facility that only showed the architectural layout on the plan and elevation. Participants were asked to individually draw the alternative design based on the final team decision on the drawings at the end of the meeting. These questionnaires were the tool to measure if the individual shared the same understanding of the selected design option with other team members. Questionnaires AB and BB were distributed after the participants filled out Questionnaires AA and BA, respectively. These questionnaires had two parts. The first part asked the participants to answer technical questions to measure the individuals’ understanding of the technical requirements and constraints of other disciplines. The second part of the questionnaires required the participants to reflect on their experience and write about the platform features that were helpful in terms of communicating the technical information, suggesting solutions, and making the final team decision. They were also asked to reflect on the platform features that prevented them from working efficiently. Questionnaire C was distributed at the end of the experiment to ask the participants to reflect on their experience in the two platforms and compare the efficiency of their team collaboration using BIM and VR.
2.4.3. Digital Setup
Two 3D models of architectural and mechanical were created using Autodesk Revit [
41]. Autodesk Navisworks was then utilized for combining both into a federated model for use in the experiment. Four viewpoints were created shown as “x” on the plans in
Figure 5. To prevent users from changing location in BIM platform, a wall was created as a boundary around the user in the architectural model using Autodesk Revit. Then, by utilizing the Visibility tools in Autodesk Navisworks, the wall was set as a transparent object. To enable users to share their screen in the BIM platform, Zoom [
42], a cloud-based conferencing software for remote online meetings was used. The VR App provided a color-coded markup tool for virtual meeting attendees. Teleportation was defined to link the viewpoints to enable the users to toggle between them in VR to explore the model. In virtual meetings, users saw the pointer of each other as a small circle with their name next to it.
Figure 6 shows the expanded 360-degree spherical photo of the mechanical rooms in scenarios A and B.
2.4.4. Physical Setup
In the BIM platform, each participant was provided a computer with access to the internet, two monitors, and a headset. Providing two monitors to the participants enabled them to have their own individual viewpoint to locally explore and mark up the model in one monitor while viewing another team member’s shared screen on the second monitor, which replicated the individual viewpoint in VR. Video conferencing was not allowed, and students used headphones to communicate verbally via audio conferencing. In the VR platform, participants were asked to use their smartphones and headphones. The research team provided VR Viewers to the participants to attach to their smartphones. Team members communicated verbally via audio conferencing using their phones while sharing the same digital space in VR.
2.4.5. Procedure
Six participating groups were named based on the platform sequence. Group BV1, BV2, and BV3 started from the BIM platform, and groups VB1 VB2, and VB3 collaborated in the VR platform first. Groups were asked to work on Scenario A to find an alternative design to accommodate the structural design change. Participants were given time before the start of their meeting to read their role-specific technical information and explore the model individually, either in BIM or VR platforms depending on the group name, to have a full understanding of the assignment description and the model. The Questionnaire AA was distributed before the start of the meeting. Team members in the BIM platform joined the meeting using the Zoom’s meeting link that was already setup. The meeting was recorded with the Zoom’s recording feature. Participants using VR, logged in to the App by entering the meeting ID, and joined the meeting. They all called a phone number to join an audio conference using their smartphone. The audio of the meeting and the screen of the observer’s smartphone was recorded. At the end of the meeting, team members filled out the Questionnaire AA. They were then given Questionnaire AB to answer. To work on Scenario B, groups switched platforms. They met online on the second platform, and the process was repeated with Questionnaires BA and BB. At the end of the experiment, Questionnaire C was distributed to capture the participants’ reflection on their experiences in both platforms.
Figure 7 presents the procedure schematically.
4. Discussion
This research study was conducted to study the effects of VR’s immersive environment and markup tool capabilities on the team’s collaboration efficiency in remote 3D coordination processes. In the asynchronous study we focused on the effects of the VR features on the individuals’ understanding of the technical knowledge exchange in a one-by-one communication method. We later studied the effects of VR features on the team’s Shared Understanding in a synchronous team interaction. On the individual level, the majority of participants reported having a better understanding of the building system conflicts in immersive VR compared to BIM. They preferred VR’s markup in the 360-degree environment compared to BIM’s markup with the screenshot of the model to understand the building system conflicts and the proposed resolution. The synchronous study results showed that VR’s immersive environment and markup tool capabilities supported team collaboration. First, all teams spent less time in VR to build Shared Understanding of the design alternatives among team members than when using BIM. Group BV3, who proposed the optimal design alternatives for both scenarios, spent significantly less time in the meeting in VR in comparison to the BIM platform. Second, among six meetings conducted in VR, three meetings resulted in correct alternative design, and two meetings had a proposed design very close to the acceptable option. In the BIM platform, only two meetings out of six resulted in the correct alternative design with considerably longer meeting durations. Third, Passive members, on average, shared better understanding of the design alternative with the team in VR. In one group, a Passive member in BIM performed as an Active member in the VR platform. He used the markup tool to communicate the structural constraints and design alternatives while he was misunderstood by other team members in the BIM platform, where he did not share his screen to explain his disciplinary constraints. Fourth, participants reported VR’s immersive environment as a feature missing in the BIM platform that supported their team collaboration. Group BV2, in particular, did not use the markup tool in VR and could communicate the design alternative effectively by asking members to use their imagination. The observational study showed that efficient team collaboration in VR required the members to properly guide each other in the 360-degree environment; otherwise, some members could not follow the conversations. In teams where most of the members shared the same understanding of the team decision, the markup creators were asking the team to first look at an object in the space like the door, and then by using the markup tool, they were guiding the team members in the 360-degree environment. Consequently, BIM’s shared screen feature was preferred by Active members since it ensured them that all members were looking in the same direction in the model. Overall, this research study showed promising results for more efficient technical collaboration among AEC professionals using immersive VR enabled with markup tools in comparison to the current BIM-based industry practices in explaining disciplinary constraints and technical analysis and brainstorming to find solutions and make decisions in remote 3D coordination processes.
4.1. Limitations
The controlled experiments in this study were conducted with a 3DOF VR that required the research team to set up the BIM platform in a way that it provided the same 3DOF experience in VR as for the BIM users. In the industry, AEC professionals explore models with 6DOF using BIM software navigation tools like Walk. The scenarios were designed in a way that they could be compared in a controlled experiment and were not real-world problems. Furthermore, the participants were graduate students with a few years of industry experience and exposure to BIM practices. This required the research team to simplify the disciplinary knowledge and define it for each role. While participants engaged in this study exercise, other settings should be explored to further validate these findings.
4.2. Future Studies
A similar controlled study with 6DOF VR is recommended to allow the team members to walk inside the model and experience it the way models are explored with BIM. In 3DOF VR, markup is created on a 360-degree static photo that allows users to see the annotation from different rotational angles while fixed in one location. In 6DOF VR, a 3D markup would be seen differently from different locations and angles. A study can be designed to investigate the advantages and disadvantages of creating 3D markup in 6DOF VR. Future experiments are also recommended to study if the avatars in 6DOF VR can resolve the team members’ disorientation problem in 3DOF VR by guiding them in the virtual environment with body language. Future research studies need to be conducted with AEC industry professionals to explore how markup enabled immersive VR can be used in day-to-day 3D coordination practices.