## 3 Results
### STL Performance Analysis  
As has previously been mentioned, the increase in resolution during the export of a 3D model results in a longer file processing time and a higher computational cost. However, in the specific case of VPP manufacturing technology, a high surface quality is usually sought in the parts obtained, so the discretisation process is of great importance, as it will decisively affect the final quality of the part. If we analyse the amount of information stored in the files (Table 3), we can see that there is an almost linear relationship with the increase in size, so the processing can become more complicated as the resolution increases, this being understood as the size of the polygons that make up the mesh. For this reason, we will analyse how this resolution and the size of the figures affect the pieces obtained. Figure 4 shows the geometries obtained, depending on the different resolutions and sizes, for LCD technology. Figure 3: Schematic diagram of the pyramid specimen. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{5}{c}{**STL File Size (kB)**} \\ \hline \multirow{2}{*}{**Resolution**} & **Elements by** & **Elements by** & **R = 10 mm** & **R = 100 mm** & **R = 1000 mm** \\  & **Kadius of** & **Edge** & & **R = 100 mm** & **R = 1000 mm** \\ \hline Highest & 10 & 8 & 94 & 950 & 9760 \\ High & 8 & 5 & 50 & 497 & 4909 \\ Medium & 5 & 3 & 30 & 297 & 2850 \\ Low & 2 & 3 & 18 & 175 & 1580 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: STL file size for a sphere with different radiuses. In the case of the lowest resolution, the polygons with which the geometry has been discretised can be seen, and as the resolution increases, the polygons into which the part is divided are smaller and therefore, less visible, until, in the case of the highest resolution, they are no longer visible to the naked eye, and the cylindrical layers that make up the part can be seen. In this way, the increase in resolution causes the upper portion of the part to go from being seen as irregular hexagons to concentric circles that are stacked to build the part. On the other hand, when analysing the influence of the size of the hemispheres, it can be seen that, regardless of the resolution, as the size of the hemispheres decreases, the manufactured features have a similar visual appearance. In this way, in parts with a diameter of 4 mm, the discretisation is not as visible, but there are still irregular shapes that make up the part. However, from 2 mm diameter parts onwards, the triangles discretised by the STL file are no longer visible to the eye, and only circular layers are visible. Thus, this is the point at which the necessary limit of resolution is found. Figure 4: Images of the hemispheres with different STL resolution and size, obtained with LCD technology. In the case of DLP technology, the result is similar: in the larger hemispheres, the triangles that form the mesh are visible, while from 2 mm in diameter, they are no longer noticeable (Figure 5). Therefore, it can be said that, in the case of the manufacture of parts with spherical characteristics with a diameter of 2 mm or less, the resolution of the mesh is not significant. However, for larger parts, a high resolution is required when meshing; otherwise, the polygons that make up the mesh will be visible. On the other hand, there are no significant differences between the two technologies; however, it can be seen that the higher XY resolution of LCD technology means that the smaller hemispheres are better defined. This is something that will have a decisive effect on the analysis of 2D deviations. However, in both cases, defects associated with the reloading of the material can be seen, which is a negative effect that appears in these processes [34,38] and which can be seen in the upper area of the figures, mainly in the larger ones (Figure 6). It can therefore be deduced that this effect is independent of the resolution of the figure and the technology.