Technical Graphics  Projection Systems  OrthographicDeciding and SymbolsHow do you know if you are looking at a 1^{st} Angle or a 3^{rd} angle Projection. It can be quite difficult to tell them apart, even for simple objects. Well there are two symbols that are used world wide and they are standard .
In both cases you have the Elevation of a
truncated cone, (the bit like a triangle). The End
Elevation of the truncated cone is on the correct side
for that projection system. Section 1 : This Lesson shows you the imaginary Glass Box and then goes onto First Angle Projection.
Section 2 : This Lesson shows Third Angle Projection. Section 3 : This Lesson shows you how to determine wheather you are working in First or Third Angle Projection. Section 4 : In this Lesson you get to put all of your newly acquired knowledge to the test with a wide variety of problems and question relating to Orthographic Projection. 


