Baobab is so powerful that it can scan either specific folders or the whole filesystem or remote computers harddisk or any mounted or unmounted devices. You can change graphical tree representation style with a simple mouse click. The disk uses percentage can be viewed as a square and rectangular graph or a colored ring. Toggle visibility with a dropdown menu from right hand side.
|Baobab-disk usage analyzer square chart|
|Baobab at main menu|
Baobab is available by default in many Gnome based distribution. But you can download it via Software center or directly from https://launchpad.net/baobab.