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Pictorial drawing: isometric and oblique

Pictorial drawings show an object in three dimensions in a single view.

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  1. PDFPictorial drawing: isometric and oblique – Technical Graphics and Design notes (ZIMSEC O Level)46.9 KB

Pictorial drawings show an object in three dimensions in a single view.

Isometric drawing

  • Vertical lines stay vertical; horizontal edges are drawn at 30° to the horizontal.
  • All measurements along the three axes are true lengths.
  • Circles appear as ellipses: construct them using the four-centre method or plotted points.
  • Start with a box (crate) enclosing the object, then cut away.

Oblique drawing

  • The front face is drawn true shape and true size.
  • Receding lines are drawn at 45°.
  • Cavalier oblique: receding lines full length. Cabinet oblique: receding lines half length (looks more realistic).
  • Place the face with circles or the most detail at the front.

Perspective (introduction)

One- and two-point perspective use vanishing points on a horizon line to show depth realistically.

Freehand sketching

Quick sketches using light construction lines help develop and communicate design ideas.

Exam tip: In oblique drawing, put curves and circles on the front face, where they keep their true shape.

Check yourself

  1. At what angle are horizontal edges drawn in isometric?
  2. What is the difference between cavalier and cabinet oblique?
  3. How does a circle appear in isometric?
Show answers
  1. 30° to the horizontal.
  2. Cavalier uses full-length receding lines; cabinet uses half-length receding lines.
  3. As an ellipse.
Next topicSections, dimensioning and assembly drawings

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