# Interactive Exploration of Virtual Heritage by Means of Natural Gestures
## 3 Materials and Methods
### Follow My Hand--Touchless Interaction Metaphor
#### 3.3.2 Navigation Metaphor  
For ISVS-B, we implemented a navigation metaphor, tackling the problem from various perspectives. The ISVS-B system implemented yet two other completely different visualization modes: one that corresponds to a completely autonomous _\"360\" virtual tour\"_ of the edifice (e.g., by default mode of ISVS-B) and another one that corresponds to a _\"first  
Figure 8: ISVS-A’s state machine describing internal states of ISVS-A according to the user’s right-hand location and gesture. Figure 7: ISVS-A interaction gestures (**a**)—interaction with entire 3D scene (**a1**) rotating the entire scene to the left, (**a2**) selecting an artifact; (**b**)—interaction with the central artifact (**b1**) grabbing the selected artifact, (**b2**) rotating the selected artifact. person\"_ perspective, completely controlled by the museum visitor (e.g., controlled mode that supposes the user's hand presence in the sensor area) (see a short demonstration of ISVS-B system: [[https://youtu.be/hT2](https://youtu.be/hT2) ChW7w4x8]([https://youtu.be/hT2](https://youtu.be/hT2) ChW7w4x8) (accessed on 20 April 2022)). In the default mode, the ISVS-B system presents a 360\({}^{\circ}\) virtual tour of a hypothetic temple located in Mangalia city of Romania (former Callatis Greek colony), situated on the Black Sea coast (former Pontus Euxinus--the original Latin name). The default camera is continuously focused on the temple and follows a closed path that turns several times around the temple at different altitudes. According to the camera's altitude, the building details of the temple are revealed to the user. This way, the user obtains not only a general view of the edifice, but also a detailed interior one, that shows her/him each constructive element in its place and order (Figure 9). Once the user decides to \"_take the hand_\" on the camera, all that he/she has to do is to place the open right hand in the sensor area for at least 5 s, and from there, the system knows that there is user interested to interact with the system, so it changes the mode and camera to a \"_first person_\" one (Figure 10). The first-person camera starts to be controlled by the user only after the perspective is changed to \"_first person_\" and the user closes the right hand. If the user retracts his open right hand from the sensor area for more than 5 s, the system regains control on the camera and turns back in \"_360\({}^{\circ}\) virtual tour_\" mode. Figure 9: The default view of the ISVS-B application: 360\({}^{\circ}\) virtual tour with a view of the constructive elements of the temple. No user interaction is required. Once the user takes control of the first-person camera, he/she may move forward/backwards, turn the camera left/right/upwards/downwards. All these actions are schematically illustrated in Figure 11.  
For the ISVS-B's state machine describing internal states of ISVS-B according to the user's right closed hand location and gesture, see Figure 12. Consequently, while the system is in the _\"first person\"_ state (Figure 12), the user may experiment free navigation by moving his closed right hand along the Oz axis, by looking around her/him at left/right turning left/right the right hand or even to look up or down by orienting the hand upwards or downwards. If one of these right-hand movements stops, the first-person camera reacts accordingly, by passing in the state that fits with the right-hand posture and position. Figure 11: User’s movements in ISVS-B’s virtual environment using the closed right hand: moving forward/backward along Oz axis (**a**); turning the camera at left/right in xOz plane (**b**); orienting the camera in the vertical plane yOz upwards/downwards (**c**).