## 4 Discussion
### Analysis of the Reconstruction Process and Additive Manufacturing of Models
Our previous studies [25] on models made with a thinner layer for surgical planning purposes indicated that the deviations were also within a similar range. Therefore, it was not decided to decrease the layer thickness but to pay attention to the economic aspect of manufacturing the models. During the manufacturing stage, we analyzed two aspects. One involved manufacturing the pelvic parts in one piece, while the other involved manufacturing three pelvic sub-areas (developed in the segmentation process) on three Prusa MK3s 3D printers simultaneously. We also conducted this test to compare different measurement strategies using CAI system procedures and to analyze the accuracy, time, and material costs of manufacturing the models. The literature provides no results regarding the time and cost of manufacturing a 3D-printed pelvic model from PLA material. Taking an average time based on the three patients analyzed, it shows that the 3D printing of the entire pelvic area took 15 h and 3 min. The model depicting the IIium area took 3 h and 12 min, the Acetabulum took 9 h and 35 min, and the Pubis and Ischium area took 2 h and 3 min. Based on the results presented in this paper, manufacturing a pelvic model in one piece or three separate parts takes approximately 15 h. The production times were comparable when using only one 3D printer. However, the publication's authors have access to a range of Prusa MK3s 3D printers. By manufacturing three separate sections of the pelvic part simultaneously across three 3D printers, the overall production time for the entire pelvic model was significantly reduced. The acetabulum area, which took the longest to manufacture (approximately 9 h and 30 min), resulted in a time savings of over 5 h and 30 min. The overall significant reduction in time was also due to the possibility for operators to optimize the orientation of the pelvic part fragments in the 3D printer space, which was not reasonably possible with a model of the whole pelvic part. Materials cost around $125 for both manufacturing concepts. Analysis of Adopted Measurement Procedures Implemented on the Atos II Triple Scan, the Measuring Arm with a Laser Head System and Alicona InfiniteFocusG4 Optical Microscope  
Two optical coordinate measuring systems illuminating the object with laser and structured light were used to develop procedures to check the geometry accuracy. For both systems, we had to use different methods to measure the geometry of the pelvic part when it was manufactured in one piece and three separate parts. To date, no such guidelines have been developed for checking the accuracy of anatomical structures of pelvic bone. When using the Atos II Triple Scan system, the choice of the measuring field and the number of steps of rotation of the measuring table significantly affected the quality of the acquired data. The measurement field is closely linked to the point cloud's resolution. A larger field decreases the resolution, while a smaller area increases it. Selecting the optimal measurement area can be challenging. This publication establishes a condition to ensure that the resolution of the obtained point cloud aligns with the manufacturing tolerance of the model created using additive technology. This condition, set at 10% of the tolerance (10% T), significantly simplifies determining the appropriate measurement parameters. When selecting the number of rotations for the measuring table, increasing the rotations resulted in more data contributing to the geometry mapping. However, this also led to increased programming errors within the 3D-STL model. The increase in rotations caused an overscan on the 3D-STL model, making it challenging to assess shape deviations accurately. Several measurement tests showed that lift generation significantly decreases when the number of table rotations is kept below 15. Therefore, for the research presented here, the number of rotations for the model created as a single piece was set at 14, while the number of rotations for the three separate fragments was set at 10.