Learning system for engineering graphics and design.

Simion, Ionel ; Dobre, Daniel ; Pascu, Nicoleta 等

1. INTRODUCTION

At Politehnica University from Bucharest there has been a great effort in curriculum redesign and particularly in Engineering Graphics field. As computer-aided design software improves, we must continuously scrutinize the teaching methods for engineering graphics education. Comprehensive, well designed materials may stimulate self-directed learning and thus influence the quality of the system as a whole.

Three-dimensional concept describes an image that provides the perception of depth. When three-dimensional images are made interactive so that users feel involved with the scene, the experience is called Virtual Reality (VR).

In the process of developing multimedia Computer Aided Instruction (CAI) software for Engineering Graphics, we have developed many techniques. Besides various graphics software and multimedia authoring tools, the students master the computer operating system, text process, image process, animation creation, www technique and so on. After comparing the advantages and disadvantages of various graphics software and the graphics file formats, graphics compress and extract, they obtained a general understanding on computer graphics technology.

2. LITERATURE REVIEW

VR in CAI acquire models in one of three ways: build them, inherit them as by products of computer-aided design efforts, or acquire them directly by sensing existing objects. Acquiring, cleaning, updating, and versioning even static world models is itself a substantial engineering task (Brooks, 1999), (Durlach & Mavor, 1995), (Larijani, 1994).

Virtual Reality Modeling Language (VRML) provide tools for the modelling of three-dimensional worlds that are functional and interactive and that can, ultimately, be transferred into fully immersive viewing systems (Hoffman, 2007). Immersion means the impression someone has of being somewhere where he is in fact somewhere else.

Our earlier works (Simion, 2005) presented models based on Computer Aided Design (CAD) in order to develop dedicated CAI systems for Engineering Graphics and Design.

3. LEARNING SYSTEM FOR ENGINEERING GRAPHICS AND DESIGN

Inheriting CAD models is, by far, the simplest way to get detailed models of designed objects, existing or planned.

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Showing the development of the model in time is an efficient way for understanding and teaching graphical models and engineering process. The time component has brought new opportunities, the 3D models becoming 4D models (Fig.1).

Modeling solids is one of our most important tasks. In the traditional way of Descriptive Geometry teaching, for example, the most difficult task for the teacher is to explain the spatial relationship among planes and objects. It is hard to illustrate the location and form of 3D objects by just drawing on the blackboard. Students always get confused.

However with the help of the solid models that were processed with CAD software like AutoCAD, CATIA so on, the construction, shapes and transposition of even subtle parts can be observed clearly.

The experience has shown that more students can understand a construction schedule more quickly and completely with 4D visualization than with the traditional draft. Fig. 2 shows an example that displays in browser some techniques for representing surfaces.

Fig. 3 shows an example that displays the intersection between a hexagonal prism and a circular cone, in order to represent a hexagonal nut. Fig. 4 shows an example that put on view the process to change an oblique plane into a plane that is perpendicular to a projection plane by creating an auxiliary plane.

Four-dimensional models can be the new way of teaching more efficient descriptive geometry and engineering graphics.

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A wide variety of geometrical topics are suitable for this kind of presentation: true size of plane figures, generating slide --and screw-surfaces and even more abstract terms like affinity and collineation can be explained that way.

4. RESULTS

The traditional way of teaching descriptive geometry and engineering graphics with pencil, T-square and triangles will be more and more replaced by electronic data processing. Drawing will stay a part of perception as the hand is an extended part of the brain. That means to teach freshmen the traditional ways of drawing while giving them the basic knowledge of geometry for their further studies, because understanding geometric principles is a key qualification of human intelligence.

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At the same time the possibilities of computer tools can be used for a better presentation. In addition to pictures of all kinds moved pictures will play an increasing role in order to achieve a better spatial imagination.

With new tools we can present geometrical context in a more efficient way. We are about to enter the virtual classroom.

Interactive 3D-graphics bears a high potential for the explanation of complex 3D-phenomena, as to be found in engineering. Modern hardware allows rendering 3D-models with considerable detail at interactive rates. The interactive handling of 3D-models is important to clarify spatial relations. Not enough effort has been spent on the combination of rendered images and textual descriptions. This paper argues that such a combination increases the potential of mere graphics to a large extent.

Students in engineering are increasingly expected to master computers as drawing tools when producing their design projects. Beside traditional drawings and physical models plots and virtual models are more and more used.

5. CONCLUSION

Tutoring programs have evolved dramatically from the simple prompt for remediation based on a wrong answer to the complex, adaptive systems of today that truly qualify as intelligent.

Virtual environment can represent any three-dimensional world that is either real or abstract. This includes real systems like buildings, landscapes, underwater shipwrecks, spacecrafts, archaeological excavation sites, human anatomy, sculptures, crime scene reconstructions, solar systems, and so on (Hoffman, 2007). These virtual worlds can be animated, interactive, shared, and can expose behaviour and functionality.

This formalized knowledge enables teachers to create and update realistic schedules rapidly and to integrate the temporal and spatial aspects of a schedule as intelligent 4D models. These intelligent 4D models support computer-based analysis of schedules with respect to cost, interference, safety, etc., and improve communication of design and schedule information.

The examples shown are some of the various CAI models experimented inside the Engineering Graphics courses at the University Politehnica from Bucharest.

The work described here is not yet complete. Future work will address further experimental validation of the model by applying it to different modules of engineering graphics and engineering design.

6. REFERENCES

Brooks F. P. (1999). What's Real About Virtual Reality?, in IEEE Computer Graphics and Applications, Available from: http://www.cs.unc.edu/~brooks/WhatsReal.pdf Accessed: 2008-03-11

Durlach N.I. & Mavor A.S. (1995). Virtual Reality--Scientific and Technological Challenges, National Academy Press, ISBN: 0-309-58725-5, Washington.

Hoffman B. (2007). The Encyclopedia of Educational Technology, Available from: http://edweb.sdsu.edu/eet Accessed: 2009-04-11

Larijani L.C. (1994). The Virtual Reality Primer, McGraw-Hill, Inc, ISBN:0-07-036416-8, New York.

Simion I. (2005). AutoCAD 2005 for engineers, TEORA USA LLC, ISBN 1-59496-033-X, Wisconsin