## 6 Practical Application and Results
### Prototyping and Evaluation  
#### 6.4.1 Rapid Prototyping  
The lean startup method [38] was employed, applying the iterative build-measure-learn feedback loop over three cycles, as detailed below. _First cycle. Built._ AR and MR interface mockups were created in PowerPoint following the design concepts from the matrix. These mockups served as a minimum viable product (MVP) as they were created with minimal resources but sufficient features to present the proposed design concepts and collect validated feedback from end users. The PowerPoint presentation was designed as a storyboard to emulate the interaction with the proposed AR/MR interfaces in an indoor construction decision-making scenario. _Measure._ The AR and MR mockups were presented in a workshop with two field managers. Participants were asked to follow the storyboards, simulating the experience of engaging with the AR/MR interfaces to make decisions and achieve goal 1.1.1. During this process, the verbal protocol analysis (VPA) was applied by asking the practitioner to think out loud while performing the task [49] to obtain feedback regarding the following: (a) the sufficiency of information to support decision-making; (b) the perceived level of SA achieved using the mockups; and (c) the workflow and perceived usefulness of the AR/MR MVP. _Learn._ It was observed that the proposed interface design allowed participants to address the decision-making task efficiently. A key observation was made regarding the workflow for accessing information. According to participants, field managers query information depending on the job or purpose at hand, whether it is a general inquiry (e.g., reviewing planned tasks' constraints within the work area) or a particular inquiry (e.g., reviewing planned tasks' constraints for a specific building element). This approach led to two ways to access information: general and particular. General access involves starting with available information in a work area and then narrowing down to the specific information needed. Particular access involves retrieving information directly through a specific element. In this context, the granularity of the BIM model must be sufficient to associate required information with specific elements. This requirement was included in the system's operational requirements in Table 3. The information access approach was included in the interaction flow of the AR/MR interaction parameter of the design matrix (refer to the design matrix in Table S1). Additional user feedback included suggestions for date format adjustments and buttons for accessing general project information. All observations and suggestions were implemented in the design matrix and the AR/MR MVP for the next development cycle. _Second cycle._ AR/MR interface mockups were developed for smartphones and the Trimble XR10 headset to test the implemented feedback in a laboratory setting. A practitioner with the same profile as previous participants conducted the test, maintaining the same design and purpose from the first cycle. Only minor style observations were made. _Third cycle._ After applying minor style adjustments, the AR/MR interface mockups were tested by a field manager at a building on the university campus. The test design remained the same, with no significant observations reported. After receiving positive feedback from the last test, the AR/MR interfaces were fully developed along with a decision support solution that adheres to the system's operational requirements from Table 3. The solution's architecture, based on the microservice approach [50], is depicted in Figure 5.  
The proposed solution has three main components: front-end web platform, back-end system, and front-end mobile application. 1. _Front-end web platform._ This is where users upload the information sources that provide data for the AR/MR solution. A plugin for Autodesfacilitate the upload of BIM model metadata. In addition, a spreadsheet was created for manually assigning the SA information requirements to building elements of the BIM model.