# VR as a 3D Modelling Tool in Engineering Design Applications
## 4 Discussion  
Considering that VR is still a new technology and only a small amount of the general public has had the chance to experience it, introducing specific tools in VR requires a great deal of user training. Due to this, the study was conducted with a focus group and included both a qualitative and a quantitative study. The results of the study show that modelling approaches in VR and desktop tools are comparable. Based on the participants' comments recorded during the focus group study and statements expressed afterwards in the questionnaire, they describe the process of modelling in VR as intuitive and fast but rather imprecise. The reader should note that the participants were given a task to create a 3D model in VR based on the reference images. All participants had previous experience with surface modelling and were familiar with a similar procedure from using desktop 3D modelling tools. Hence, they had an idea of the main phases (steps) comprising the modelling process: insertion of images, creating reference curves, creating surfaces, and finalizing the model. The participants quickly got a hold of using the controllers and the features of the software tool and several times they mentioned that VR enables better and more realistic spatial perception than desktop tools, making it intuitive to use. Considering the measured time for different phases (steps) of modelling, it is evident that the creation of a freeform model in VR is faster than using a desktop interface. However, comparing deviations of the output models from the VR and the desktop modelling studies, it can be seen that VR modelling lacks precision. During the focus group test and in the questionnaire after the modelling, several participants commented on the lack of tools in VR  
Figure 11: Participants’ opinions on the use of VR technology in different design phases. that could provide more accuracy. Moreover, even though the VR environment is preferred for viewing the final model, aligning the geometry in VR according to the reference images seems to cause issues, as the images are viewed from a 3D perspective instead of the planar viewpoints as in desktop interfaces. In the current state, VR modelling software has some important features missing, such as missing zebra stripes or other surface quality evaluation tools. Therefore, if an error is identified in later stages, the user is required to go back to the VR environment to adjust it. Essential information about the model, such as dimensions and the enclosed surface volume are also missing. Therefore, it requires more post-editing of the form to achieve a solid model of acceptable quality. Nonetheless, our study showed that the transformation of the surface model into a solid body is possible using the appropriate tools, even if the quality of the model is not the finest. Solid body exporting options are missing in the current tools, however, the model can be exported as a mesh file, which can then be transformed into a solid body using a variety of programs. Furthermore, these tools require a quality mesh to achieve a good result and entail additional know-how. Design review in VR has many reported advantages over the traditional process. There, the conversion from a solid body to a model appropriate to be used in VR is also a time and resource-consuming process. However, if the model would be initially created in VR, it would already be ready for the design review, which would shorten the time for the preparation of the review. The model could then be quickly edited in the same environment and afterwards converted to a solid body, when the final shape is decided. Additionally, an important feature missing that would allow the users to create more technical models consisting of basic geometric shapes are the Boolean features. In this respect, a new feature would also be necessary for the application in mechanical engineering, which would enable the inclusion of multiple assembly components in the VR environment.