## 3 Materials and Methods
### Questionnaire Design and Validation
#### 3.3.2 Modified Questionnaire and Validation  
In this research, the ARI questionnaire [19] was modified and utilized to evaluate users' perceptions of digitized and digital 3D models of sculptures in terms of immersion in AR. Since the primary content of the AR experience consists of static 3D models of artistic sculptures, we modified the ARI questionnaire to suit AR applications focused on 3D objects. The modified version of the ARI questionnaire was used to evaluate users' perception of each 3D sculpture (digitized and digital) in AR, as well as their overall experience with the AR application for displaying sculptures in public spaces. The overall experience and general impression of using the AR application to present digital sculptures were evaluated by measuring the level of engagement in AR. The perception of each sculpture in AR was assessed by measuring engrossment and total immersion with each 3D model of the sculpture. The structure of the proposed survey was organized as shown in Figure 1.  
Since the original ARI questionnaire was tested on AR applications designed for learning or entertainment, its items were formulated to measure users' perceptions during an interactive activity in AR. To adapt the questionnaire for the AR application based on 3D objects, specifically digital 3D models of sculptures as the main AR content, we revised the original items, primarily by replacing the term \"activity\" with \"3D object\" or \"sculpture\". For this research, the items were translated into Serbian language.  
To evaluate the reliability of the modified questionnaire, [PERSON]'s Alpha was calculated to assess the internal consistency of the modified items within each category. To achieve acceptable internal consistency (\(\alpha>0.70\)) in the analyzed categories, the last item was excluded from the emotional attachment subcategory, because it primarily resulted in a [PERSON]'s \(\alpha\) of 0.61. This item was more focused on the interactive experience during the AR activity. However, since the proposed AR app was designed for a non-interactive experience, its removal, based on the Item-Total Statistics, increased the scale variance. After this adjustment, the [PERSON]'s \(\alpha\) for the modified emotional attachment subcategory improved to an acceptable value of 0.76. The [PERSON]'s Alpha values for each main  
Figure 1: Diagram of the structure of the proposed survey with evaluation elements.  
category of the modified 20-item questionnaire, along with their subcategories, indicated good reliability (Engagement: \(\alpha\) = 0.74; Engrossment: \(\alpha\) = 0.88) and high reliability (Total Immersion: \(\alpha\) = 0.91), as shown in Table 3. The results demonstrated that the questionnaire, modified to measure immersion in the AR application featuring 3D object augmentation, can be considered reliable.  
To evaluate users' perceptions of artistic digital and digitized sculptures in augmented reality, four subcategories--emotional attachment, focus of attention, presence, and flow were additionally analyzed. Composite scores were calculated as the mean of responses for each subgroup, and correlations between the dimensions were assessed. The correlation analyses revealed expected positive relationships, with the strongest correlation observed between focus of attention and flow (r = 0.90). Other dimensions, such as emotional attachment and presence (r = 0.78), also demonstrated significant associations, supporting the theoretical framework of the questionnaire. The correlation matrix of these dimensions is presented in Figure 2.