Throughout their learning processes at our university, students of mechanical, organizational and electronic engineering use Computer-Aided Design (CAD) packages in various CAD/Computer-Aided Engineering (CAE)/Computer-Aided Manufacturing (CAM) studies. It is necessary to develop spatial visualization ability when the computer is used as a design tool, in order to be able to see and understand the operation of the complex mechanisms in the CAD package. This visualization ability must be developed during the initial stages of the engineering learning process. Spatial representation systems were the tools used to develop this ability until the introduction of CAD packages. Nowadays, the acquisition and development of spatial visualization ability requires autonomous learning, learning that uses educational platforms, and within graphic engineering, a common tool that is independent of any software (3D viewers) and which makes it possible to review the 3D models.
An early trend still in use today in the viewing of 3D models is to insert them directly into the website using a plugin. Initially, the most commonly used standard format, VRML (Virtual Reality Modelling Language) was normally used, in web environments, in viewers such as Cosmo Player and Cortona. This VRML format has not been developed any further since 1997, but it has been used in various graphic engineering teaching applications, such as the visualization workshop at the University of Burgos (Ramos Barbero et al., 2003), in mental rotation exercises for the development of spatial abilities (Rafi, Anuar, Samad, Hayati, & Mahadzir, 2005), and in the ME-105 "Computer Aided Engineering Graphics" course at the Middle East Technical University of Turkey (http://www.me.metu.edu.tr/courses/me105/Outlineindex/outlineindex.htm). The "WEBD" project, designed under the Leonardo da Vinci International Programme, also used the VRML format initially, but in its new "3DWebEPL" version (http://www.gig.etsii.upm.es/moodle) it uses several viewers such as 3DVIA-Composer, Viewpoint Media Player and eDrawings (Ciobanu, Tornincasa, & Ciobanu, 2009).
A new ISO standard--extensible 3D (X3D) Graphics (Web 3D Consortium, 1999)--is the next generation VRML language. X3D constitutes an improvement over VRML and opens up a wide range of applications for web-based collaborative visualization in distributed product development. For example, Chih-Hsing Chu (Chu, Cheng, & Wu, 2006) has developed an application, in which it is possible to view various configurations of a 3D product using SpinFire (collaborative visualization utilities), an applications server, and a PDM system.
Choosing the most suitable viewer in a particular environment, with specific needs in mind, is not a simple. We have to bear in mind the following four points: the CAD package in use; whether a 3D publisher is integrated into the CAD software or whether an external one is used; whether a viewer or a plug-in is used; and its format type. In the engineering applications environment, Ron LanFon (LaFon, 2007) assesses the features of the following 3D publishers: SpinFire, Adobe Acrobat 3D, MYRIAD, XVL Studio Pro, QuadriSpace, Right Hemisphere and eDrawings, most of which have trial versions and free viewers.
In the teaching/learning of graphic engineering we can also use these viewers for the manipulation of parts and mechanisms in the initial learning of visualization skills and in the subsequent self-review of various exercises by the students themselves. The manipulation of 3D models using viewers is also useful to us in teaching, in understanding the operation of the devices and their assembly, if these have their simulations incorporated, but unfortunately, there is no standard viewer that covers all web-based 3D information sharing needs. An early study aimed at assessing the features of viewers with regard to their use in teaching was carried out by Tornincasa (Tornincasa & Chirone, 2002). …