PPT Slide
It is sometimes asserted that one disadvantage of a globe is that one cannot see all of the entire earth at one time. But you can if you use the transformation ?’ = ?, and ?’ = ?/2. This maps the entire earth onto one hemisphere, as shown in the orthographic view that follows. Repeat this for the backside of the globe and hardly anybody will notice that every thing appears twice. East-West distances are of course foreshortened. There are other ways to do this.
? is latitude, ? is longitude