Tips for Projection of Straight Lines

1. The simplest position a straight line occupies in a space is, it is parallel to both V.P and H.P.


2. The above position resulting in straight line as a top view and front view.
   


3. For any other position first assume the given line parallel to both the planes.
   


4. Then decide the view which will give us the true length of the line and true inclination.


5. Rotate this view to the given angle to get the final view.
   


6. Project from it to get the other final view.
   

For example:

• If a line is inclined to H.P, the front view will have the true length and true inclination.


• Therefore rotate the front view to the given angle (θ -theta) and project this line to get final top view.

• If a line is inclined to V.P, the top view will have the true length and true inclination.


• Therefore rotate the top view to the given angle ( φ-phi) and project this line to get final front view.

(Picture Coutesy:http://www.georgehart.com/cccg/Image71.jpg)