## 4 Discussion
### Lessons Learned from the Design and Evaluation of Each Application Case Study
It includes a self-directed trial in Tallinn's Town Hall Square, during which participants explored the AR application on their own, mirroring how they would naturally use it in a real-world context, giving the test ecological validity. Following that, in-depth, open-ended interviews were conducted to gather detailed user feedback. Theme-based content analysis, a widely used qualitative method, was then used to categorize and interpret the interview data. This involved identifying recurring themes, \"higher-order themes\", which represent broad, overarching categories of user experiences or issues, and \"lower-order themes\", which are more specific subcategories that fall under each broader theme. Taken together, these methods not only revealed key usability insights but also captured participants' emotional responses, ultimately guiding designers toward more user-centered improvements. The Fountain of the Lions application use case builds on the previously mentioned triangulation design explanation, in this case combining personas, heuristic evaluation, and a cognitive walkthrough. However, this study employs a 3D cognitive walkthrough (3 DCW) specifically adapted for evaluating three-dimensional user interfaces. It also used a 3D heuristic evaluation (3 DHE), which offers a more targeted inspection process for 3D applications. This adaptation is essential in AR/VR assessments because standard walkthroughs do not adequately account for spatial tasks--such as rotating objects, zooming in or out, and navigating through 3D worlds--nor do they address challenges like depth perception or unusual gesture inputs. By examining each step in a 3D workflow, evaluators can pinpoint where users might become confused or stuck, and propose interface improvements and redesigns accordingly. The 3 DCW ensures that designers capture issues unique to 3D environments, leading to more robust, user-friendly experiences in AR and VR contexts. The Picasso AR app use case highlights a lean, entrepreneurial approach to XR product development through Design Thinking/Design Doing and validation of an MVP. It showcases a real-world application of how UXUI prototypes, market research, and user feedback can inform the development of engaging cultural heritage experiences. The Picasso AR app enables users to engage in a virtual conversation with a stylized digital avatar of [PERSON], placed in front of his birth house in Malaga, Spain. On-location, the AR experience allows tourists to activate [PERSON] through their phones--prompting storytelling, facts, and interactions contextualized to their physical location. Pre-visit and post-visit, users can access the virtual version remotely in VR, continuing the dialogue with [PERSON] and exploring related artworks and biographical elements. The special feature of this case study is that it is accompanied by a slide-by-slide MVP pitch deck. Each slide represents a different stage of development:  
* Initial UX wire-frames and storyboards based on persona insights;
* Interactive mockup screens designed using prototyping tools like Figma;
* A concise market analysis outlining tourist demand for creative AR experiences at iconic cultural locations;
* User validation results, gathered through early testing with representative end-users, including tourists, local guides, and museum stakeholders. This MVP validation phase used structured feedback tools and interviews to evaluate desirability, usability, and perceived educational and entertainment value. The direct integration of user feedback into the next design iteration is an example of a lean, agile development pipeline, applied in the context of digital cultural tourism. The [PERSON] AR use case provides a practical template for cultural entrepreneurs, designers, and educators seeking to bring heritage experiences to life through immersive, physgital applications--grounded in real-world validation, scalable design systems, and user-centered storytelling.