Engineering Graphics

Projections of lines

Straight line

A line is a geometry having length but no thickness. It is a locus of points moving linear. It can also be said that the straight line is the shortest distance between any two points 

The location of line is specified by the specifying the distance of its ends from the reference planes  It may be

·         Parallel to both HP and VP.

·         Parallel to one HP/VP and perpendicular to the other.

·         Parallel to one plane (HP / VP) and inclined to the other.

·         Inclined to both HP and VP.

Projection of a line

The projection of a line is obtained by projected its finish points on planes of projections then connecting the points of projections. The projected length and inclination of a line, is totally different compared to its true length and inclination.

The different cases are:-

Case 1. Line parallel to a plane

Case 2. Line inclined to a plane

Case 3. Projection of a line parallel to both HP and VP

Case 4. Line perpendicular to HP & parallel to VP

For Further reading the description of the cases the students can refer the link given below

http://nptel.ac.in/courses/112103019/19