# Beyond Human Vision: Unlocking the Potential of Augmented Reality for Spectral Imaging
## 2 Method
### Step 3: Development and Deployment of Unity Software Solution  
In order to interact with the digital models in a meaningful manner in the context of spectral imaging, the simple upload of the generated models to a third-party 3D model visualizer on the Hololens 2 would be extremely limited. Indeed, a complete toolset requires not only the visualization of the model but also the interaction with the spectral data. This means, for example, integrating a window to analyze the spectral signal, as well as additional solutions to shift between different spectral maps for the same sample and even putting multiple samples side by side for integrated analysis.  
For that purpose, we opted to develop a tailored software solution, building a Unity project within a 3D Universal Windows Platform adapted to the Microsoft Hololens 2 headset. Unity is a game engine that can be used to create 3D and 2D interactive content. Unity excels in real-time rendering, which together with its cross-platform capabilities make it a natural choice for a versatile approach to addressing the major challenge of the manuscript [32; 33]. In addition, to better explore AR capabilities, the Mixed Reality Toolkit (MRKT) package was utilized in the project. The MRKT adds a unique collection of components and advanced functionalities such as spatial mapping, hand tracking, and eye tracking, which are essential for creating immersive and interactive AR experiences.  
In Figure 1 (right), we present the designed interface, composed of a text box, a drop-down menu, a 2D graph, and the sample itself. Each one of these components has a particular function in the interface, with the information updated according to that contained in the loaded model. The text box displays the sample name and the dropdown menu, the relevant features for which we previously generated the spectral maps (e.g., element lines for LIBS). By interacting with this icon, the user can switch between spec  
Figure 3: Three-dimensional models constructed using photogrammetry techniques: (**A**) Map of cobalt emission line at 345.3 nm, superimposed on a patterned tile model. (**B**) Map of iron emission line at 259.9 nm, superimposed on an oxidized wrench model.  
tral maps. The 2D graph displays the image previously generated in the second step, which contains the average spectroscopy signal for the sample. Finally, in the center of the interface, the model of the sample appears, displaying the selected spectral map seamlessly overlaid on the sample surface while preserving the relevant object texture information. We added collision properties and object manipulator functions to the objects alongside the GameObjects interactions tool to provide the elements with all the necessary gesture-based interactions.  
Finally, a menu window can be utilized to access additional functions. Among these functions, the first button allows us to hide all elements of the interface, except for the sample and menu to achieve an environment with fewer distractions. The second allows us to access a list of samples, enabling also the simultaneous display of samples to facilitate comparative examination. Finally, a third function activates a QR code reading mode to allow users to move the sample to their desired location, which can be utilized to load models directly from a remote server in the future. All of these buttons have the particularity of being voice-activated, allowing the user to have hands-free operation for other tasks.