amount of inofrmation from one system to the other

Hi, my question is very broad. I recently tried to understand a tutorial using polar coordinates in moving the camera about. The coordinate was described in (theta, radius). What I don't understand is theoretically how one can get more information from a lower information state: example, cartesian coordinates (x,y,z) from polar(theta,r). Please forgive any assumption that I may have violated, etc., the polar coordinate system is pretty new to me.:confused:

Also why would I want to use a polar system over s cartesian?