If a line segment AB doesn't lie on a ray of projection, then its horizontal and vertical projections are line segments A'B' and A''B''. 

If a line segment AB is on an oblique line, then its projections have
smaller length, i.e. d(A,B) > d(A',B') & d(A,B) > d(A'',B''). This fact is obtained from the properties of the right trapezoids shown in the picture on the right. 



Lines AB i CD are parallel to Π_{1}, their horizontal projections are in true length. 
Lines EF i GH are parallel to Π_{2}, their vertical projections are in true length. 
Line IJ is parallel to the ground line x, both its projections are in true length. 
Created by Sonja Gorjanc 3DGeomTeh  Developing project of the University of Zagreb.
Translated by Helena Halas and Iva Kodrnja.