# Creating a Haptic 3D Model of Wenceslas Hill in Olomouc
## 2 Materials and Methods  
This article aims to describe the process of creating an interactive haptic 3D model of Wenceslas Hill in Olomouc, which depicts its historical state and is accompanied by a tablet computer that serves to present additional information. To fulfil the said goal, TouchIt3D technology was used [38]. The 3D model contains several surfaces that react to touch, providing interactivity. For a user-friendly way of displaying desired information about the object or its parts, the tablet computer serves as a part of the resulting model. In addition, several solutions for conducting an electrical signal in the case of the models, which are composed of multiple parts, were designed. The created haptic 3D model holds an ambition to serve as a tool for enriching knowledge about the given area. Wenceslas Hill is located in the city of Olomouc, Czech Republic. On the top of Wenceslas Hill, Olomouc Castle is situated. There are many significant places of interest in the area of the castle, with the most distinctive one being Saint Wenceslas Cathedral [39]. Other places of interest include a partly preserved Romanesque palace, and the Chapel of St. Anne and Chapel of St. Barbara. The area has seen a multitude of architectural makeovers throughout history, especially the cathedral. The model described in this article depicts the area of Wenceslas Hill in the eighteenth century. The current appearance of some of the buildings in the area is shown in Figure 1.  
The basis for creating the printed interactive model was a 3D model of Wenceslas Hill in Olomouc, depicting the area in the eighteenth century. The model was originally designed as part of a time series of 3D models presenting Wenceslas Hill in several historical periods. For the process of 3D modelling, SketchUp (sketchup.com) ver. 18 from Trimble was used. The model contains 180,108 polygons. Most of the polygons (121,078) form a generated digital terrain model (DTM), which serves as the model base. Without the DTM, the rest of the model has 59,102 polygons. The model was modelled in LOD 3 [40]. It was created by referencing available historical material from the target time period (e.g., sketches, historical drawings) for the Olomouc Museum of Arts. The eighteenth century model was chosen mainly due to a suitable level of detail for modifying and subsequently printing the model. Figure 1: The current appearance (as of the year 2022) of Saint Wenceslas Cathedral (**a**) and Chapel of St. Anne (**b**) (source: authors). TouchIt3D technology served to design the conductive parts of the model and create designs for conducting electrical signals for 3D models composed of multiple parts. The idea behind TouchIt3D is to provide interactivity by combining a device with a touchscreen with a model printed on a 3D printer. The technology uses a combination of conductive and non-conductive materials for 3D printing. The material used for printing was polylactic acid (PLA), both for the conductive and non-conductive parts. The basic principle of TouchIt3D technology is the use of any 3D model with parts modelled for the purpose of being printed using conductive material. The conductive part, containing carbon, reacts to touch and can then conduct an electrical signal. To provide interactivity, the technology is accompanied by a touchscreen device with interactive virtual buttons. Upon touching a chosen conductive part, additional information about the conductive part is shown on the display of the device. The technology was implemented using the process of 3D modelling that served to design and place parts of the model, which are to be conductive in the resulting printed model. Figure 2 shows the steps needed to implement the TouchIt3D technology. When implementing the technology, a workflow was followed to ensure proper functionality. The workflow is presented in detail in Section 2.3. The model was printed on Craftbot FLOW IDEX XL.