## 2 Materials and Methods
### 3D Modeller Layer  
According to the previous description, 3D coordinates can assign a position to every generated model and, following this reasoning, the dimensions and orientations of bipunctual and multipunctual elements as well. From this perspective, particular tridimensional shapes, meshes, can symbolise both the dimensionality and material composing a find (e.g., a cube can represent a punctual flint artefact, and an entire spherical pipe can denote a bipunctual flint artefact) (see Table 1). Similarly, specific colours, namely textures, on the 3D model presentation can typify the stratigraphic unit of provenance (e.g., a green texture can indicate the US08 stratigraphic unit, and a blue texture can indicate the US06 stratigraphic unit) (see Table 2). From this optic, the mesh-creator software component, through a 3D toolset graphic environment (Blender), receives the group of CSV files created during the preceding phase and employs a Python script to generate and organise the 3D models into a digital asset exchange (DAE) repository. DAE constitutes a 3D interchange file format that complies with ARKit v. 2.0 for digitally codifying 3D models. With the five attributes (ID, position, number of points, US and material; see Section 2.1), such a script fetches every CSV file to produce the related typology of the artefact (see Table 1), a predefined 3D shape (punctual, bipunctual or multipunctual) that takes into account the number of recorded points, their position, and the find's material. Likewise, the colour is univocally assigned to that 3D shape based on its stratigraphic unit (see Table 2). Subsequently, the resulting 3D model is uniquely identified by allocating the ID as its filename. In this light, every 3D model is generated on an accurate positional basis (georeference) (see Figure 4). \begin{table}
\begin{tabular}{c c} \hline \hline \(\text{Type}059\) & \(\text{Type}10\)Slaps \\ \hline \hline \(\text{Punctual}\) lithic (PL) & Cube (1 point) \\ Elongated lithic (EL) & Entire spherical pipe (2 points) \\ \hline \(\text{Punctual}\) rocks (PR) & Pyramid (1 point) \\ Dimensional rocks (DR) & Six-point connected pipe \\ \hline \(\text{Punctual}\) bones (PB) & Sphere (1 point) \\ Elongated bones (EB) & Half spherical pipe (2 points) \\ \hline \(\text{Geological}\)/dating sample (GS/DS) & Bell shape (1 point) \\ \hline \(\text{Geological}\)-level limits (GL) & Multiconnected pipe (several points) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Typology vs 3D shape used by the Les Cotüés mixed reality (MR) application. Figure 4: Example of Les Cotüés georeferenced 3D models. \begin{table}
\begin{tabular}{c c} \hline \hline \(\text{Strictographic Unit}\) & \(\text{Geitoun}\) \\ \hline \hline US01 & Light green \\ US02 & Yellow \\ US03 & Orange \\ US04 Upper & Red \\ US04 Lower & Brown \\ US05 & Violet \\ US06 & Blue \\ US07 & Cerulean \\ US08 & Green \\ Dating sample & Cyan \\ Geological sample & Beige \\ Geological-level limits & White \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Stratigraphic unit vs colour used by the Les Cotüés mixed reality (MR) application. Additionally, the script uses an editable configuration table for customising both couplings, typology vs 3D shapes (see Table 1), and the colour vs US (see Table 2). Accordingly, the user can apply at will, and in conformity with the dimensionality of the find, other combinations besides those shown in the current manuscript. Such associations do not follow any standard. Hence, they are solely decisions made by the user for adapting the application to a specific excavation guideline. Should it be necessary, the programmer could add additional 3D shapes to the script to represent other materials. In a nutshell, the mesh-creator software component generates a spatial tridimensional database that contains the whole group of 3D models related to the excavation. Such a database univocally distinguishes a particular 3D model using its corresponding unique ID.