Three-dimensional models' usage in courses placed on Moodle platform

Three-dimensional models’ usage in courses placed on Moodle platform Shuletea Angela, Dintu Sergiu

Virlan Petru

GDDTI Department, Technical University of Moldova Chisinau, Republic of Moldova [email protected] [email protected]

EM Department, Technical University of Moldova Chisinau, Republic of Moldova [email protected]

Abstract— One of the biggest benefits of virtual education is the ability to easily explain complex processes and principles using animations and interactive 3D models. The purpose of this study is to determine which 3D software product should be used for the display of interactive graphic engineering documents, so that the visualization and manipulation of 3D models provide useful support to students of industrial engineering. In order to create these didactic materials a multitude of tools can be used: AutoCAD, SolidWorks, Inventor, Adobe Acrobat Pro etc. This paper proposes some examples of the above-mentioned didactic materials, including animations and interactive 3D models used in Moodle.

without additional IT studies. Another requirement for these tools is the accessibility of software used to create and visualize in terms of the cost and simplicity of their use by both the content creator and the final consumer.

Keywords — distance learning; e-learning; Moodle; 3D; interactive; CAD; cloud services; educational motivation; Learning Management System LMS; 3DPDF

 3D objects obtained with PowerPoint tools (fig.4, 5, 6);

I. INTRODUCTION An important task in specialists’ training in mechanical and electromechanical engineering is the formation of spatial imagination necessary in the process of working with technical documentation. This task is carried out during the years of study, but the base of spatial imagination development was laid in the early years, and this task is a challenge for teachers. Obtaining and developing the ability to read technical drawings requires autonomous learning, using educational platforms that allow spatial viewing of objects. Pieces and mechanisms studied in technical disciplines can be presented on these platforms in the form of three-dimensional models. Technologies used for this purpose are one of the most important e-learning tools that are so indispensable for low frequency and distance learning. Using them, various didactic materials can be created, that assist the study of the construction of the parts and teaches the principle of operation of the mechanisms. These 3D models, which replace sometimes quite expensive real parts and mechanisms, are accessible to a large number of users and are an alternative that should not be neglected in the educational process. Interactive virtual models offers the possibility of studying in detail the various mechanisms by rotating them, creating sections or removing elements of the construction. Among the various methods of creating and displaying interactive 3D models used in different domains [1, 2] we chose those tools that allow content creation by teachers

In general, the spatial objects used in a presentation can be created by the following methods:  2.5D objects - plane images with spatial pattern (fig.1, fig.2);  Images of 3D models created in one of the CAD software and saved in GIF, PNG, etc. (fig.3);  animated 3D models, saved as AVI, FLV, MP4, etc. (fig.7);  interractive 3DPDF format models (fig. 8-13). II. POWERPOINT SPACE OBIECTS A familiar tool for all teachers is the PowerPoint presentations software. Effective use of PowerPoint capabilities allows creating dynamic and expressive presentations that have an increased impact on listeners. To create such a presentation text, images, animations, videos, simulations, etc. are used. Spatial models and animations of the processes and operations examined are of particular importance.

Fig. 1. 2,5D obiects in the „Shape” menu.

Fig. 2. Flat colored figures with gradient.

The current versions of PowerPoint allow the creation of various 3D objects and their animation. To create 2.5D PowerPoint objects, it offers 3 types of shapes (shape): cube, cylinder, pyramid trunk. These figures can be colored, or they can be attributed to different textures. In the process of coloring, the program provides for the specific tinting of the spatial objects (fig.1). The same type of objects can be created by gradient coloring of flat figures. For example, a sphere can be created from a circle, a cylinder - a rectangle and an oval, a cone of a triangle and oval. The combination of gradient and transparency allows the representation of a transparent sphere (fig.2).

Fig. 4. PowerPoint space objectst.

Creating spatial objects is possible in PowerPoint. With 3-D Format and 3-D Rotation from the Format menu, different buttons or rotating surfaces can be created from the circle. Aligning and arranging shapes at different heights relative to the horizontal plane allows the creation of objects with a complex configuration (fig. 4). The Combine Shapes tool recently appeared in PowerPoint allows you to represent pieces of various shapes. For example, the Oval and Cross shapes can be used to create a straight groove with straight flanges. The reunion of the small circle with crosses takes the flanks and the groove foot surface, and the intersection with the large circle - the groove head surface.

When objects are to be moved only in the xOy plane without rotation around the Ox and Oy axes, isometries executed in CAD software and exported in one of the image formats may be used. The images so captured can then be animated in PowerPoint. With various tools, including on-line, from a series of consecutive images, gif animations can be created, which are then introduced into presentations (fig.3).

Fig. 3. Animated images of isometric projections.

Fig. 5. Parts created în PowerPoint.

Fig. 8. The 3D model shown in the A360 viewer.

Fig. 6. Obtained 3D objects by image fill.

To obtain a nut, a circle (Oval) was dropped from a hexagon. The profile of a toothed wheel was accomplished by combining (the intersection and reunion) of a 32-point Star with circles, and the hole with a wedge channel - by subtracting a circle and a rectangle (fig. 5). Various shapes can be combined, reunited, filled with images. Obtained objects can be given volume, thus being transformed into 3D objects (fig.6). III. 3D STATIC IMAGES AND ANIMATIONS Depending on the task of the teaching material, it can include various multimedia elements - from the simplest images to the interactive three-dimensional models of the mechanisms. In the process of preparing such a teaching material it is necessary to create the 3D model in one of the CAD software (e.g. AutoCAD, SolidWorks, Inventor, SketchUp etc.). The models we propose are executed in Inventor Autodesk. We have chosen this software for the following reasons: Inventor is software with an interface and a familiar way to engineers in the energy and mechanical field that a large part of the teachers working in these domains has and is provided by Autodesk Company free for 3 years for students and teachers.

In order to get a photorealistic image, the CAD model is assigned with a texture, after which it is saved in one of the image formats - JPEG, BMP, PNG, etc. The image is included in the content of the electronic course as a separate file or as a part of the text files. To demonstrate the construction of parts or mechanisms, they can be created animations of the models (fig.7). The animations saved in AVI, FLV, MP4 format can be uploaded to the Moodle platform as media files or in the form of addresses to web file storage services of this type. IV. 3D INTERACTIVE CAD MODELS During an electronic course, 3D interactive models represent a real use. Unlike static images and predefined animations, interactive models allow various manipulations: rotation, movement, sectioning, etc. Model sharing methods are different and depend on the possibilities of the computer, internet network, software available, etc. The model saved in one of the native CAD packages (DWG, DWF, etc.) can be placed as a resource on the Moodle platform. This file is downloaded to the computer by the student and is viewed in one of the software's CADs. In this case, you can view the file with one of the free installation views (e.g. Design Review, CAD viewer, Bentley, etc.). The ability to quickly access of a particular file from any computer, laptop, smartphone, or tablet through a browser is done through free online viewers (e.g. Autodesk A360 Viewer, 3DViewerOnline, ProfiCAD Viewer, etc.). Most of them offer online data storage services on the server. Thus, the models can be stored in the cloud, and only the address to this file is placed on the platform (fig. 8). A series of viewers (e.g., Sketchfab, Cubize, 3DViewerOnline, ShareCAD, etc.) generate model embedded codes (fig. 9). Embedded features provide a simple and quick way to add complex media information to Moodle. An advantage of this strategy is the ability to use another site as a hosting service and interface for data transmission.

Fig. 7. . Avi-type animation.

Interactive three-dimensional images significantly increase the perception of information by students. They can individually configure the three-dimensional scene: the distance to the object, the angle of view and the mode of displaying the surfaces, the various effects, the scale and the size of the object. They can visualize information about quotas and annotations that are not visible in the original PDF file.

Fig. 9. Sketchfab embed code.

The embedded viewer is placed on the Moodle page in a window showing the content. To embed 3D model it will be loaded on that site, and then will be generated the code that will be entered into the platform's web page resource. V. 3D INTERACTIVE MODELS OF PDF FORMAT One way of presenting three-dimensional models in electronic courses is to incorporate them into PDF files. PDF format has become an internationally recognized standard (known as ISO 32000-1) for document sharing at any level. 3D PDF is a standard PDF file (format that supports images, texts, links, multimedia content, etc.) that contains one or more dynamic and interactive 3D models viewable through the free program Acrobat Reader. 3D PDF allows moving, zooming, rotating and choosing the way of displaying the surfaces and various effects (lighting, transparency, etc.). Navigating to the structure and components of the ensemble is an interactive, exciting process and provides a profound understanding of the project. This is an intuitive and cost-effective solution, capable to improve and enrich the documents. Such multimedia, dynamic and interactive documents justify the effort made by the teacher to create an explicit and realistic teaching material and enable the document to be used remotely.

Fig. 10. Individual task on "Views".

3D PDF offers the possibility of representing both an integral mechanism and the hiding of the pieces to highlight a single piece or a coupler. This type of file allows you to segment planed objects where you can choose them and examine the smallest details of 3D objects in one interactive illustration. If necessary, the teacher can emphasize certain parts of the object, defining a set of views that the student can choose from the list in the menu. This list is defined by a small set of parameters, which does not increase the size of the document, as opposed to a similar set of static images. But the biggest advantage of such documents is the ability to be read in Acrobat Reader, a free software that is virtually indispensable in any computer. For the first year students, with the study program of energy and mechanical, were created variants for individual tasks in themes "Views" (fig.10) and "Simple sections" (fig.11). The variants include the interactive model 3D PDF and a graphical instruction for using the mouse and the toolbar. In the drop-down menu can be selected basic views (in the "Views" theme) and can be seen the track with different sections (under "Simple Sections"). For students who are just beginning to study the technical drawing, this type of material is of real use, helping them to form orthogonal projections of views and sections.

Fig. 11. Individual task on "Simple Sections".

To create the 3D PDF files there was implemented threedimensional models using the Inventor software. This software offers various tools for modeling and allows integration of the plugin that creates 3D PDF files. In the absence of this plug-in, the various converters (e.g., Tetra 4D, PDF3D, Bentley View V8i etc.) can be used. Bentley View is a free version of 3D PDF from a DWG file. The captured file can be edited then in Adobe Acrobat. Here, can be created and saved the default views, background, size, and position of the image in the sheet. Inventor 2017 and 2018 include new features that allow direct 3DPDF spaceport export. Models created with Inventor can contain preset views that can be selected by the student in the 3DPDF file review process. For assemblies, it is possible to display or hide assembly components (fig.12). Exploded views describe assemblies by moving components out from their assembled position (fig.13). Inventor creates exploded views by using a combination of assembly, presentation, and drawing files. A view of the assembly is created in the presentation file, and the components are repositioned in the view. Drawing views are then generated from the presentation file. The free PDF3D plug-in for PowerPoint lets you view 3DPDF files and interact with the model within a slideshow. The tool displays the interactive PDF 3D model in a defined slide region, and allows various manipulations such as rotation, magnification, segmentation, quoting, etc. PDF3D PowerPoint is an add-on that appears after installation on the PowerPoint 2010 (or more recently) toolbar. [7]. Fig. 13. Animation on the theme "Removable joints”.

From the team of authors a series of 3D models used in the lectures on the "Technical drawing" discipline on the first year at the engineering specialties were created. For students' individual work, 125 models (25 variants) were created for the following subjects: - Views; - Simple sections; - "Cover" type piece; - "Shaft" type piece; - "Gear" type piece. The models will be introduced into the education process of this year and will facilitate the creation of views and sections of some pieces and replace the real pieces needed for the theme "Sketching". VI. ADDITIONAL FUNCTIONS FOR 3DPDF FILES

Fig. 12. Slide of the presentation on the theme "Joining in wedge”.

The 3DPGF file creation and editing software offers a diverse range of additional tools that could considerably improve 3DPDF.

The new Inventor Presentation compartment provides the opportunity to create various scenarios that could demonstrate the assembly process or operation of the mechanism. (fig 13). These features have been retrieved from Inventor. SimLab Composer 8 (Mechanical - $ 499) allows various operations with spatial patterns. Models can be created, edited, dimensioned, mutually aligned, etc. It is possible to combine the models created in SimLab with those imported from other applications. SimLab supports models from more than 20 different graphical applications (including AutoCAD, CATIA, SolidWorks, 3D Studio Max, Inventor) and exports them to formats such as 3D PDF, HTML5 / Web GL, U3D, etc. SimLab offers the ability to create animations by determining key frames or tracking a path [8]. Adobe Acrobat 3D ($ 699) allows for additional interactive functions for 3D objects embedded in PDF documents. 3D objects can be edited, combined with other types of files, highlighted, texture can be changed, animations created and more [9]. 3D PDF Pro (1798 $) creates virtual assembly and disassembly animations, workflow simulation, step-by-step instructions along with animated 3D PDFs [10]. Tetra 4D Enrich (36,547.91MDL) is the only solution that allows anyone to create interactive and rich 3D PDFs inside Adobe Acrobat Pro without a programming experience. The interactive 3D PDF created with Tetra4D Enrich functions as an "application" that has all the data needed to support any work process with all the information needed to manufacture the product. [11]. VII. CONCLUSION In academia, education, and in the public in general, the trend is towards enhanced media. Rich internet applications such as animations, movies and interactive demonstrations are becoming the norm. Yet, despite the fact that PDF files are capable of supporting fully interactive 3D spatial and temporal content, the use of those features within the scientific community has been almost non-existent. To-date, the utilization of 3D capabilities in PDF has been largely relegated to engineering applications incorporating CAD designs.

The ability to embed 3D objects and enable the time evolution of information in standard PDF documents opens up whole new dimensions of information transfer. Users have the ability to interact with the content, customize the view, and obtain more information than is possible using static 2D images [12]. Although creating and editing 3D models in PDF format requires some skills, it does not require special knowledge, and in the meantime appear new tools, thanks to which multimedia creation is becoming simpler. In the future, when the 3D PDF support will appear in browsers (a feature that only Adobe Reader now has) the using of this type of image could become more efficient. With the help of enhancement of HTML editing tools, the illustrating of the on-line scientific publications with multimedia materials can become an alternative to the 3D PDF format. REFERENCES B. R. Barbero, C. M. Pedrosa, & E. G. Maté,”Assessment of 3D viewers for the display of interactive documents in he learning of graphic engineering”, Educational Technology & Society, 15 (4), 2012, pp.167– 180. [2] David Brazinaa, Rostislav Fojtikb, Zuzana Rombovac, ”3D visualization in teaching anatomy”, Procedia - Social and Behavioral Sciences 143, 2014, pp 367 – 371. [3] Aydın Çetin, İnan Güler, ”3D Technology selection for a learning management system with analytic hierarchy process, Conference ICL2010, Hasselt, Belgium, pp.1051-1058. [4] O. Ciobanu, S. Tornincasa, G. Ciobanu, ”Web based learning and training in the field of the enterprice product lifecycle using 3D technologies”, 5th international scientific conference eLearning and software for education, 9-10th April 2009, Bucharest,Romania [5] O. Ciobanu, S. Tornincasa, “The use of dynamic interactive 3D images of biomedical devices in education,” Second International Conference in Visualisation, 15-17 July 2009, Barcelona, Spain, pp. 40-43. [6] S.O. Kotov, “Interactive 3D objects in educational resources of MOODLE“,Open and distance education. 2015. № 4(60), pp,5-11. [7] https://www.pdf3d.com/products/pdf3d-in-powerpoint/ [8] http://www.simlab-soft.com/ [9] http://www.adobe.com/aboutadobe/pressroom/pressmaterials/pdfs/Acro bat_3D_AAG.pdf [10] http://www.3dpdf.com/en/client-solution/features.html [11] https://tetra4d.com/tetra4d-enrich/ [12] http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-15295.pdf [1]