Keywords

1 Introduction

The rapid and unexpected change in on-line teaching in the last two years has forced faculty members of graphic expression to adapt the procedures, incorporating new technologies. The large amount of technological innovations of current smart glasses, mobile devices, videogame engines and web applications is of great importance. In this context, there are different realities that comprise the broad spectrum between reality and virtuality (i.e., “virtuality continuum”) [1]. Terms such as AR, VR, MR, XR and DR, as well as other future realities, require an adequate definition to understand the future we can expect from their application in teaching [2].

These realities are integrating into current university education, specifically in the degrees of Agronomic Science and Rural Development Engineering and Forest Engineering of the University of Cordoba (Spain). One of the advantages of teaching the contents in the classroom is the feeling of surprise when the students integrate the exercises into their spatial vision and understand how a three-dimensional space is represented in two dimensions. These future professionals gradually develop their spatial vision as we advance in the complexity of the exercises.

However, courses such as this and the previous one, where the education system reevaluated the way of teaching and the classrooms became empty, this type of technologies have posed an essential element to bring the contents of the subject matter in Engineering Drawing in the abovementioned degrees to the homes of the students. In this context, it was necessary to create and apply a new way of sharing the exercises, in order to allow the students to delve into the subject with improvements regarding the experience of spatial visualisation. Remote learning is a work method that removes the limitations of the geographic location of the people involved [3].

MR has a marked multidisciplinary character that notably connects complementary scopes, such as the education sector and engineering [4]. There are currently numerous applications that coexist with some type of technology linked to MR. The aim of the present study is to show the importance of applying these technological innovations in university education, identifying the methodology used for the virtualisation of engineering drawing exercises.

1.1 The Different Realities

MR (or XR) is a combination of what we know as VR and AR. Nowadays, it is possible to create three-dimensional models of high geometric and visual quality through 3D reconstruction and photogrammetry, obtaining very good results, which makes it a fundamental tool for heritage documentation, analysis and dissemination [5]. The numerous applications require a rigorous multidisciplinary procedure (with architects, engineers, documentalists, pedagogists, historians...) that guarantees the quality of the results.

XR can be applied in very different fields [6]:

  • History and documentation of the space or object of the intervention.

  • Data collection for archiving with historical rigour.

  • Processing of photogrammetric models

  • Editing and advanced comparative analysis in photogrammetry.

  • Optimisation and correction of digital models for 2D/3D visualisation.

  • Presentation of the virtual model.

Zhou, Lou and Yang [7] describe AR as an overlapping of digital graphics in a visor that allows seeing the real world. AR overlaps alterations on an existing environment, keeping the user connected to the physical reality observed; on the other hand, in VR, the user plunges into an artificial virtual world that aims to replace the outer reality. That is, although VR and AR share hardware technologies, the trend seems to indicate a constant growth in AR.

The use of VR goggles, mobile phones or tablets for AR, which allows adapting the learning pace, provides numerous benefits in this regard. The user can move freely throughout the content to obtain a better understanding and assimilation of the concepts. Thus, the use of these resources increases the spatial vision capacity of the user.

2 Methodology

The digital means employed by techniques such as WebXR [8] provide the necessary tools for remote experimentation. This practice allows not only to continue with the teaching task but also to improve the experience of the user and motivate his/her learning.

2.1 Exercises in CAD 3D

From a complete archive of engineering drawing exercises of the Department of Graphic Engineering and Geomatics at the University of Cordoba (Spain), some exercises of both the dihedral and axonometric systems were selected for visualisation (Figs. 1, 2, 3, and 4).

Fig. 1.
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An example from the online library of the engineering drawing exercises of the Department of Graphic Engineering and Geomatics (UCO).

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Fig. 2.
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Image of an exercise of the dihedral exercise (graphic formulation and solution) – 2D paper version.

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Fig. 3.
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Schematic view of the representation of an exercise of the axonometric system.

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Fig. 4.
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Screenshot of what the user sees in the screen of the HMD visor.

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2.2 Procedure Used in the Virtualisation

Sketchfab provides an online platform that is easy to use and allows converting these resources to their digital twins, which makes it a valuable tool for teaching. Students with poorer spatial vision are involved with greater interest in the exercises, as they visualise them from their own computers, tablets or mobile phones, through a web interface. The steps to follow for the virtualisation of the exercises are summarised as follows:

Step 01

Preparation of the exercise creating its 3D digital twin in a CAD programme. Three-dimensional geometry is employed in a modelling software, paying special attention to the concepts of scale and welding (unions) of the vertices.

Step 02

Selection of the thickness of the lines of the CAD figure to improve its spatial visualisation. To this end, there are two types: cylindrical and rectangular (Fig.5).

Fig. 5.
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Transformations applied through modifiers of the original geometry.

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Step 03

Application of colour codes, to indicate greater or lower importance to each layer, with the aim of obtaining a visually more attractive space that improves the experience of the user (Fig. 6).

Fig. 6.
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Colour codes selected for an optimised narrative.

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Step 04

Assignation of material to each layer of the model.

Step 05

Exportation in the format created by Wavefront Technologies in 1992 (object files: *.OBJ). To integrate the file in a web browser, it is necessary to export it in the OBJ format. This is an open-format file of geometric definition that has been adopted by most providers of 3D graphic applications.

Step 06

Online work in a professional WebXR visor, e.g., Sketchfab, in which the geometry is imported and a series of modifications are performed, such as: orientation of the geometry, lighting control, colour assignation, scale adjustments in VR, and some adjustments of movement sensations. The advanced lighting controls and the representation of materials itself allow recreating the virtual space with a good detail level. The annotation tool allows setting several predefined views, which enables the students to go over the exercise in a tutored and autonomous manner.

3 Results

The procedure allowed developing a uniform methodology to virtualise engineering drawing exercises in 3D, which can serve as a guide to other faculty members of similar subjects. This approach allows the specialised faculty to prepare a catalogue of practical exercises and share them in a website with their students. Figures 7 and 8 show how the platform employed in this study allows, through a university account, accessing advanced functions, such as space customisation and visualisation limit control.

Fig. 7.
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Online editing and setting module through the Sketchfab platform.

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Fig. 8.
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Screenshot of online VR setting through the Sketchfab platform.

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With the abovementioned controls, it is possible to configure the exercises to enable the students to experiment through the use of VR goggles (Fig. 9).

Fig. 9.
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User with Head-mounted virtual goggles visualising an exercise.

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During the experience, it was observed that not all students used a computer with high performance, and the Internet connection was not always at high speed. Therefore, it is very important to optimise the exercise, in order to ensure that the graphic engine (mobile, tablet, computer) has enough resources to load the data fluently and quickly [9].

3.1 Virtual Reality Application: Metrics

The approval of an innovation project within the Innovation Plan and Good Teaching Practices of the University of Cordoba allowed obtaining the needed material to carry out and verify the suitability of its application in the classroom. A seminar on Mixted Reality: ‘A tool in Covid-19 times’ was held to evaluate the impact on teaching using this kind of innovative technologies.

Figure 10 shows the results extracted from the survey conducted to 17 people of different educative contexts, who were given the opportunity to visualize the exercises with their devices remotely. They were asked about their ICT knowledge.

Fig. 10.
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Users ICTs knowledge.

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Figure 11 tends to evaluate the improvement on the spatial vision and have a better understanding of the exercises by using this technology of VR.

Fig. 11.
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Assessment of the user’s spatial vision.

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Fig. 12.
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Satisfaction level of using 3D tools on (1) spatial vison improvement; (2) having a better understanding of the exercise in the space; (3) identification of the mistakes in the space and (4) understand what is represented on the paper in 2D.

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Finally, the level of acceptance of the visualization device (tablet, mobile, laptop or VR goggles) was analised and whether this new resource was considered motivating among other issues.

From our results, we can confirm that 90–100% of the surveyed people much improved their spatial vision in an excellent way. 80–90% people preferred the 3D system since they better understood the exercises spatially. 75–85% better understood their mistakes in the space. And, finally, around 90% better understood the exercises overview than with the 2D representation (Fig. 12).

4 Conclusions

With the aim of further adapting and improving the teaching-learning process, with the increasing implementation of new technologies in the field of education, it was possible to establish a method for the 3D virtualisation of exercises. Such virtualisation method allowed students to visualise the three-dimensional models of the exercises with any device from wherever they connected to the Internet, thus demonstrating its usefulness.

The procedure presented in this study shows the value of the physical archive of the engineering drawing exercises of the Department of Graphic Engineering and Geomatics at the University of Cordoba (Spain). The use of a digitalised resource allows guaranteeing its future application with the new technologies discussed in this article.