## 4 Results
### Digital 3D Models of the Jug  
#### 4.1.1 3D SLS and Postprocessing  
When scanning the jug (Artec Spider), three scans were made at different positions of the object on a manually rotated table covered with a special texture ensuring proper positioning of subsequent points of the surface taken from the object (Figure 4a). The resulting files containing all point clouds and object texture information were 1.12 GB in size. Information on individual scans is presented in Table 3. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No** & **Features** & **3D SLS** & **SfM** & **Comments** \\ \hline
3 & Texture data acquisition & RGB information * & 2D photos & * selective uptake \\ \hline
4 & Digitisation of transparent objects & No & Partially & \\ \hline
5 & Data form & Point cloud & 2D photos & \\ \hline
6 & Data size & Several GB & Several to several hundred MB * & * Camera dependent \\ \hline
7 & Software & Specialised, device-dedicated & Device-dedicated/Open source & \\ \hline
8 & Computer hardware & High computing power & Low computing power & \\ \hline
9 & 3D model building & Point cloud & Triangulation using image analysis & \\ \hline
10 & 3D model generation & Manual, assisted & Automated & \\ \hline
11 & Costs & High/Very High & Low & \\ \hline
12 & Availability & Low & Widespread & \\ \hline
13 & Time consumption & Low/Medium & Low/Medium & Object-size dependent \\ \hline
14 & Acquisition of dimensions & Yes & No/Yes * & * Necessity to place tags \\ \hline
15 & Model quality & Very good & Small/medium & \\ \hline
16 & Making it photorealistic & Texture mapping & Texture mapping & \\ \hline
17 &
\begin{tabular}{c} Possibility to export to standard formats \\ \end{tabular} & Yes & Yes & \\ \hline
18 &
\begin{tabular}{c} Possibility to modify models \\ \end{tabular} & Yes & Yes & \\ \hline
19 &
\begin{tabular}{c} Competence in using the equipment \\ \end{tabular} & Specialist/High & Common/Medium \\ \hline
20 & IT competences & Specialist/High & Common/Medium \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._
After carrying out all stages of the postprocessing (Figure 5), a mesh model with 214,870 vertices and 429,736 faces was obtained. The size of the.obj file was 30.1 MB, while the texture for surface mapping with dimensions of 4096 \(\times\) 4096 pixels and the horizontal and vertical resolution of 96 dpi saved in the.jpg format was 7.1 MB. The results of the SLS scanning of the jug are shown in Figure 7a,b. Due to the large number of vertices and faces in the model grid and the large size of the.obj file (Table 4), the mesh was reduced using the free Blender program. For this purpose, the Decimate tool was used, which allows to change the coordinates of the vertices, and thus the walls, in relation to the original model. The Decimate tool permits one to modify the mesh of the model using one of the methods: Collapse, Un-Subdivide and Planar. Based on the experience gained earlier, the authors used the Collapse method. The actions performed led to a tenfold reduction of the model mesh, resulting in 21,488 vertices and 42,972 faces (Figure 7c,f). This resulted in the size of the.obj file being reduced to 4.31 MB. The texture has also been changed from 4096 \(\times\) 4096 px to 2048 \(\times\) 2048 px. The file size after.jpg optimisation was 953 kB. Despite the use of such large simplifications, they did not significantly deteriorate the quality of the model and its texture. It is true that there is no spiral in Figure 7d, which is visible in the base drawing (Figure 7a), but after applying the texture, the differences between the drawings are generally not visible (Figure 7b,e), and it is the 3D models covered with textures which are presented in virtual museums.