In Technical Illustration, reference lines are often used to assign text or position numbers to specific parts of an illustration. It only takes a little refinement to polish the reference lines.

In a technical illustration comprised of several single parts, you often use reference lines to assign position numbers to the respective parts. When applying these lines, however, you have to keep one thing in mind: Since these lines cross other lines of the illustration, it is important that they can be distinguished from each other. The reference line should not disturb the displayed element. This can be accomplished by shadowing or haloing the lines. In the illustration above, you can see two representations; one with shadowed lines, one with unshadowed lines.

Even in this relatively small-scaled illustration, you can clearly see that the shadowing of the reference lines allows for improved optical detachment of the displayed parts and the reference lines. If your graphics program does not support automatic exposures, you can create a wide white line to lie beneath these reference lines. IsoDraw does this automatically.