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Theory of Shape Description in Pictorial Representation

This article provides an overview of the theory of shape description in pictorial representation, including axonometric, oblique, and perspective drawings. It explores the different types of pictorial drawings and their applications in various industries. CAD and examples of pictorial representation are also discussed.

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Theory of Shape Description in Pictorial Representation

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  1. Pictorialrepresentation Flóra Hajdu B406 hajdfl@sze.hu

  2. Content • Theory of shapedescription • Pictorialdrawing • Axonometric • Oblique • Perspective Hajdu Flóra

  3. Theory of shapedescription • In technicaldrawingsvarious projection methodsareusedtorepresentobjects • Projection is a method of representingvisually a 3D objecton a 2D drawingpaper • Pictorial projection is a method of producing a 3D objectthatshows 3 main faces Hajdu Flóra

  4. Pictorialdrawing • Oldestwrittenmethod of communication • Usedin design, production, assembly, service, sales • Usedto • Explaincomplicatedengineeringparts • Helpdesignertowork out problemsinspace • Trainnewemployees • Speedup and clarifythe assembly of a machine • Transmitideasfromonepersontoanother • Developthepower of visualisation Hajdu Flóra

  5. Types of pictorialdrawings Pictorialdrawing Axonometric Oblique Perspective • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Hajdu Flóra

  6. Axonometric projection • Projected view • The lines of sightareperpendiculartotheplaneof projection • 3 faces of a rectangularobjectareallinclinedtotheplane of projection • The projections of 3 principalaxesmaymakeanyanglewithoneanotherexcept 90o Hajdu Flóra

  7. Axonometric projection • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Axonometric projection Isometric Dimetric Trimetric 3 principalfaces and axes of theobjectareequallyinclinedtotheplaneof projection 2 principalfaces and axes of theobjectareequallyinclinedtotheplaneof projection All 3 faces and axes of theobjectmakedifferentangleswiththeplaneof projection Hajdu Flóra

  8. Axonometric projection Hajdu Flóra

  9. Dimetric (engineering) projection Hajdu Flóra

  10. Developing an axonometricdrawing • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Hajdu Flóra

  11. Oblique projection • Basedontheprocedure of placingtheobjectwithoneface parallel tothefrontalplane • Placingtheother 2 viewsonobliqueplanestoleftor right, top orbottomat a convenientangle • The 3 axes of projection arevertical, horizontal and receding • Advantage: showingonefacewithoutdistorsion Hajdu Flóra

  12. Oblique projection • Facesto front: • The facewiththegreatestirregularity of outline orcontour • The facewiththegreatestnumber of circularfeatures • The facewiththelongestdimension • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Hajdu Flóra

  13. Oblique projection Oblique projection • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Cabinet Cavalier Alllinesare made totheirtruelengths Linesontherecedingaxisareshortenedbyonehalftheirtruelengthtocompensatefordistorsion scan Hajdu Flóra

  14. Cabinet projection Hajdu Flóra

  15. Developing an obliquedrawing (Cabinet) scan • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Hajdu Flóra

  16. Perspective projection • Perspective is a method of drawingthatdepicts a 3D objecton a flatplaneasitappearstotheeye • The drawing is made bytheintersection of thepictureplanewithlinesofsightconvergingfrompointsontheobjecttothepointsightwhich is locatedat a finitedistancefromthepictureplane • Perspectivedrawingsare more realistic • Commonlyusedforpresentation, illustrations, architects Hajdu Flóra

  17. Perspective projection • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Perspective projection Parallel Angular Oblique 1 vanishingpoint 2 vanishingpoints 3 vanishingpoints Hajdu Flóra

  18. Perspective projection • Source: C. Jensen, J. D. Helsel, D. R. Short: Engineering Drawing&Design Hajdu Flóra

  19. Construction of 2-point perspective Hajdu Flóra

  20. CAD • 3D modeling • Generation of perspectivedrawings • The position of the ,,camera’’ representsthepersonviewingtheobject • Severalparameters (zoom, distance, viewclip) aremanipulatedtocreatetherequiredperspectiveview of theobject • Onlytheview is manipulatedtheobjectremainsunaffected Hajdu Flóra

  21. Pictorialrepresentaionexamples (CAD) Hajdu Flóra

  22. Pictorialrepresentationexamples Hajdu Flóra

  23. Summary • Pictorialrepresentation • Axonometric • Oblique • Perspective • Pictorialrepresentationexamples • Nextweek: Ortographic representation, first angle and third angle projection

  24. ThankYouforYourattention!

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