REACTIVATING GRAPHICAL SUBJECTS Rein Mägi Tallinn University of Technology Estonia

Contents Introduction Descriptive Geometry examples Technical Drawing examples Computer Graphics examples Conclusion

Introduction Drawing is the Language of Engineering Engineering Graphics develops students’ space imagination and could be applied also in other disciplines - mathematics, physics, chemistry etc But Graphical Subjects (Descriptive Geometry, Technical Drawing, Computer Graphics) are quite serious and difficult for students Everything that could increase the efficiency of teaching in this area is welcome Some reactivating means (jokes, puzzles, tricks, attractions etc) are illustrated by specific examples

Descriptive Geometry examples (1) The simplest geometrical object is a point, defined by x. y, z coordinates mms://media.ttu.ee/YGK3350/Mituvaade.wmvmms://media.ttu.ee/YGK3350/Mituvaade.wmv But more exciting is to research the position of the point M concerning the real object (block) Is the point M located on the block or not? Auxiliary view A can answer to this question We can see even the distance d from the block

Descriptive Geometry examples (2) Quite interesting picture-puzzle for student is to make up the third view by two given views Humorous human image can activate their spatial imagination

Descriptive Geometry examples (3) Which is the left view of this object? Other solutions (2, 3, 4,…) need more spatial fantasy. Usually only one version (cube) is proposed by students

Descriptive Geometry examples (4) The main property of parallel projection is illustrated by horizontally flying plane The shadow of the horizontally oriented airplane is congruent to the origin plane Therefore (L2=L1) we can determine the length of the plane L1 by measuring the shadow’s length L2 But is it realistic or not ?

Descriptive Geometry examples (5) How to remember 5 variants of cone sections? Connection with some daily object, for example conical wine glass, is quite witty possibility to save this knowledge

Technical Drawing examples (1) According to international standard ISO 128-1:2003 technical drawings should be unambiguous and clear For any feature of a drawing there shall be only one interpretation. It should be easy to understand for each involved person Do you understand what is this? The answer: cowboy on the bicycle

Technical Drawing examples (2) The modern trend is using interesting logos for companies or for persons For example, 3D-logo of Rein Mägi in two views Quite puzzling variant is to create 3D wire bent figure for initials But what is the spatial structure of this logo? Only isometric view can help to understand

Technical Drawing examples (3) Mechanical engineering drawings should be accommodated with dimensions, tolerances and indications of surface texture How to explain more cognizably these technical concepts to beginners? One visualization way is to imagine the “ Lord God ” tries to measure the diameter of the Earth Is it possible to measure the diameter with tolerance ±1 meter? Why not? There is two ways to solve the problem : 1) to smooth the Earth ’ s area by bulldozer 2) to be conciliated only with precision ±10 kilometers Which of these two variants is more workable?

Computer Graphics examples (1) Present students (future engineers) must undoubtedly learn Computer Craphics This know-how is unavoidable for creating modern technical drawings and also for understanding and for handling computer drawing files Is the Computer Graphics really the most rational drafting method? By our research the fastest way was freehand sketching, but the quality and preciseness were unsatisfying How long does it take to create the CAD-file? Command Time can show us the real time But when concluding a contract with the customer we should predict the probable working time: the more precisely the better

Computer Graphics examples (2) What is the correlation between predicted and real time? Our test-exercise with students......showed that this correlation- factor was +0.6

Computer Graphics examples (3) Which is more rational – 2D or 3D technique? The answer depends on the final object – 2D drawing (hand- made or computer-graphical) or 3D solid model A modern engineer could operate with all of them 3D-modeling allows creating quite mystic spatial objects: This is a solution … Such kind of tabouret - is it possible?

Computer Graphics examples (4) Quite attractive is 3D-modeling of Moebius surface among real objects People Moebius surface Trees Summer- house More attractive is 3D-modeling of Moebius surface as merry-go- round: mms://media.ttu.ee/YGK3350/2008_03_klipp3.wmv

Computer Graphics examples (5) Using CAD is also associated with specific “ surprises ” How to solve the problem? The right solution is: Dview >Twist>180°. This is the source object AutoCAD problem in 3D- modelling is that the Bottom view is rotated 180° Do not Rotate the object 180°!

Computer Graphics examples (6) For beginners computer graphics arouses some serious complications. Sometimes the humor can help Murphy's Law says – every computer works better if it is switched ON. But by the improved Murphy's Law recommends: At first to switch OFF and then switching ON (Restart)

Conclusion Engineering Graphics is indispensable language in engineering, but quite difficult subject for students Engineering Graphics is a foundation for other technological disciplines – mechanical and civil engineering Therefore every reactivating way is welcome in this area All means (jokes, puzzles, tricks, attraction etc.) should increase students' interest and motivate to solve graphics problems Good examples are these associated with engineering reality

A picture is worth 1000 words! Thanks for your attention!