# VR as a 3D Modelling Tool in Engineering Design Applications
## 1 Introduction
### Background and Objectives
[2] researched how VR technologies can provide more natural and intuitive interaction between the designer and the CAD system using different sensory channels. It was found that VR can provide better support capabilities for conceptual design through its multiple interface integration and implementation, making the 3D sketching more intuitive and quicker, as there is no need to additionally reproduce the design in the CAD system. [PERSON] et al. [1] tested the VR-supported conceptual design against traditional sketching on paper. The Gravity Sketch VR application with a virtual reality head-mounted display (HMD) was tested by a group of product development students where parameters like efficiency, ease of use and enjoyment were measured. Results have shown no significant difference between the quality of hand-made and VR-made sketches. A similar study conducted by [PERSON] et al. [32] showed that the industrial design students find conceptual modelling using VR interesting and a positive experience, however, there are some issues to be considered, e.g., that the lack of surfaces produces inaccuracies in the model and that people draw better on a 2D surface than in 3D space directly. Nonetheless, the users were able to create the desired shapes and models in a rather limited time frame, showing that VR provides good support for quickly generating 3D concept models. Investigating sketching in different environments, [PERSON] and [PERSON] [33] stated that immersive 3D sketching is a unique tool that simultaneously supports behaviors that are commonly only found in paper-based sketching, CAD modeling and physical model making. In these studies, the VR-created concept models are built from and represented as a set of surfaces, but they lack an explanation of how the models can be used for further product development. In the next step, engineers have to transfer the surface model into a manufacturable model. This means that the geometry has to be fully enclosed (solid CAD model) and the transitions between the surfaces have to be well defined in order to be able to perform simulations and analyses on the models [34], as well as to produce technical documentation and use it as input for manufacturing. The surface model can be transformed into a mesh model so that the VR generated geometry can be further manipulated. [PERSON] and [PERSON] [35] argue that the virtual mesh model can not provide a suitable mathematical surface quality, thus a CAD replica of the shape is also necessary. [PERSON] et al. [36] took a different approach and proposed a methodology for direct solid modelling in VR. This reduces the need to replicate the design created in VR again in the CAD software. It is based on constraint-based geometry manipulation, which resembles Boolean operations in desktop CAD software. Even though this methodology is suitable for designing simple geometrical objects, it does not provide good support for complex freeform designs. Currently, available VR modelling applications and available features for solid geometry manipulation show that this approach has not gained significant traction. To address these concerns, our research objective was to determine whether 3D modelling in VR can be used after the conceptual design phase to facilitate the embodiment from a product concept into its final form (3D model) following the engineering design process. If proven successful, this would reduce the need for switching between desktop CAD and VR environments during product development, thus reducing the time and the required designers' efforts. To further explore the main research question, different parameters were considered including the possibility of converting a VR-created model into a sold CAD model and the usability of VR modelling tools in terms of speed, intuitiveness of the tools and the modelling process, as well as the output model quality. The metrics used was the modelling time, degree of task completion, overall usability and the quality of the final 3D model.