Isometric Scale
Isometric projection is drawn using Isometric scale, which converts true lengths into isometric lengths which are foreshortened. (“Edges of an object are foreshortened” means that “the edges are cause to appear as if shortened”.)
METHOD I
- Dia.1 Draw a horizontal line AB.
- From A draw a line AC at 45º to represent actual or true length and another line AD at 30º to AB to measure isometric length.
- On AC mark the points 0,1,2,etc., to represent actual lengths.
- From these points draw verticals to meet AD at 0′,1′,2′,etc. the length A1′ represents the isometric scale length of A1 and so on.
- In Isometric projection, actual (true) length of an object is foreshortened i.e., in the isometric projection, all the edges of an object along the direction of the three isometric axes are foreshortened to 0.82 times their actual/true lengths.
METHOD II
- Dia.2 draw a horizontal line AC = true length.
- Mark the division points of true length on AC as 0,1,2 and 3.
- At the point A, draw a line inclined at an angle of 15º to AC.
- Also, at the point C draw a line at an angle of 45º to CA. Both meet at D.
- Draw lines parallel to CD through the points 0,1,2 and 3 to meet AD at the points 0′,1′,2′ and 3′. The line AD gives the isometric lengths.
