Reply To: What is the orthography? I don't really understand the difference between the perspective and orthography.

Perspective has depth and foreshortening. Orthographic projection displays all lines with true bearing and scale. These traits make it an ideal projection for navigation charts.

Here is a good thread.
http://blender.stackexchange.com/questions/648/what-are-the-differences-between-orthographic-and-perspective-views