I am working on an interactive map which displays various pieces of geographic information about a person - places worked, education, holidays taken, home addresses etc.. All in all there are 9 categories.
I am representing the data using colored circles to depict location (information about location revealed on rollover).
As there are so many categories I am going to need a color code legend of some sort.
I would like to add functionality also that allows user to view a specific category or a number of categories at any one time, depending on their wants. So for instance if user wishes to just view job history, he/she selects that in legend and only corresponding gree circles are displayed, the others fade out to about 50% opacity.
I had initially thought about putting checkboxes beside each legend item and user could turn them on/off. With an option for 'view all' at the top. This however feels too clunky too me and will add too much noise and visual weight to the device.
Would it work better to make each legend a button in itself with a subtle on/off state - once again with a 'View Al'' button on top?
Should I even been making a legend interactive or are there better techniques?