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Lines and Areas

Lines and Areas. Projections of lines and areas Meaning of lines and areas in orthographic projections. Projection of Lines. A. B. A line may be projected in its true length. A line may be fore-shortened. A line may have a point as its projection. Projection of Lines.

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Lines and Areas

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  1. Lines and Areas • Projections of lines and areas • Meaning of lines and areas in orthographic projections

  2. Projection of Lines A B

  3. A line may be projected in its true length • A line may be fore-shortened • A line may have a point as its projection

  4. Projection of Lines Foreshortened A Foreshortened True length B

  5. When will it be seen as a point? When it is perpendicular to a picture plane. View • . • . III-Angle If seen as a point in one view, true length in other views!

  6. Reading Areas • A plane surface will always appear in a principal view as a line or an area

  7. Reading Areas • An plane surface that appears as a line in one view is normal to that view. It may or may not appear its true shape in the other views.

  8. Reading Areas • An plane surface that appears as a line in two of the principal views appears as a true shape in the third view.

  9. Reading Areas • A plane surface that appears as an area in two of the principal views cannot be in true shape in any view.

  10. Reading Areas • A plane surface that appears as an area in two of the principal views cannot be in true shape in any view.

  11. Reading Areas • A plane surface that appears as an area in two of the principal views cannot be in true shape in any view.

  12. Reading Areas • Any view that shows a plane surface as area shows it in a like shape

  13. Reading Areas • Any view that shows a plane surface as area shows it in a like shape

  14. Reading Areas

  15. Meaning of Lines in Orthographic Views • An edge view of a surface • An intersection of two surfaces • A surface limit - reversal of direction of a curved surface

  16. Meaning of Lines in Orthographic Views Surface limit Intersection edge view

  17. Meaning of Lines in Orthographic Views ∎ ∎ ∎ ∎ Another Example ∎ ∎ ∎ ∎ Edge view ∎ ∎ ∎ Intersection ∎ ∎ ∎ ∎ ∎ ∎ Surface limit ∎ ∎ ∎ ∎ ∎

  18. Meaning of Areas in Orthographic Views 1. A surface in true shape 2. A foreshortened surface 3. A smoothly curved surface 4. A combination of tangent surfaces

  19. Meaning of Areas in Orthographic Views B B B Surface in True shape Foreshortened Surface

  20. Meaning of Areas in Orthographic Views C C D D C D Curved Surface Tangent Surfaces

  21. Reading Areas Oblique surfaces appear as areas of like shape in all views

  22. Reading Areas Adjacent Areas lie in different planes. If two areas were in the same plane, there will not be any boundary between the two.

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