## 4 Discussion
### Limitations  
1. Memory. More than 35,000 artefacts and features were excavated and recorded during the Les Cottes excavation project [24]. Therefore, the current technological representation of such a vast quantity of elements would hinder the memory capacity of the mobile device. Consequently, it is noteworthy to emphasise that the script should reduce the number of faces and clean up some edges to render the 3D model of the artefact as simple as possible. Moreover, a further enhancement could be achieved by separating the 3D model's data loading and the scene instancing. Finally, a progressive rendering approach should also improve the performance of the application.
2. Precision on the positioning. A further aspect deals with the manual positioning of the 3D model clusters by utilising georeferenced graphical markers as anchors. It is important to mention that such a technique has to intrinsically operate a detection of the contour of the structure (plane) on which the virtual object needs to lie by using tracking methods supplied by ARKit v. 2.0. Nevertheless, the anchoring process faces several repositioning problems due to mainly two factors: * A loss of precision in the sensor device (inertial measurement unit (IMU)). * A deterioration of alignment accuracy due to a reduction of light detection. Such anomalies render the position of the 3D cluster unstable and can create a flickering effect that may complicate the interactive examination by the archaeologist in situ. At this point, it is useful to highlight that by employing the manual placement, the in situ positional precision of the 3D cluster depends on both the visual accuracy of the operator and the number of anchors utilised. We estimate, from our mensuration, that it may vary up to several centimetres (\(\pm\)5 cm), even if an exhaustive statistical analysis of uncertainty and error measurements has not been accomplished due to the inaccessibility of the site at the time of this writing. Hence, such examinations remain outstanding and should still be completed. Instead, the employment of a nonelectronic marker-based positioning, namely graphical pattern signs, could bring the profiles into line with higher precision (estimated to \(\pm\)1 cm). However, in this case, the excavation must provide different permanent markers as anchors on its contour. Finally, it is significant to remark that the desktop environment permits the photogrammetry skeleton and the entire 3D excavation cluster models to fit together with high precision for analytical and positional purposes (same scale and references).  
Figure 10: (left) Distribution of assemblages (bones and flint) at Les Cottés, after [24]; (right) distribution of assemblages (angular view) (bones, flints, samples, rocks and geological layers) at Les Cottés.  
3. Blurry visualisation. In particular scenarios, some 3D models show a blurry contour on the image. Such unclear result derives from the rendering methodology applied by ARKit v. 2.0 on the format of the model (DAE) since the same visualisation in Blender does not raise this problem.
4. Extension of the site. Every archaeological site can implement the procedures applied for the Les Cottes cave. However, in the case of extensive excavations, the process should subdivide these broad areas into smaller spots, simulating a continuity among the different subsites and simultaneously dealing with each one by employing distinct anchoring references.