Step 1 – The Image of the hand-drawn sheet depicting the orthographic views is acquired by means of a flatbed scanner
(grayscale – 8 bit).
The scanning resolution needs to be selected resothat separate lines in the drawing remain separate in the resulting digital image (Fig. 2).
In practice, this requires to have at least 3–4 ‘‘white’’ pixels separating each drawing line. Typically,
an indicative resolution value can be 150 dpi for a line thickness drawing in the range 0.5/1.0 mm.bject