2 | Debug | Unregulated output for debugging purposes.

Level 1 should make clear to the user that the program is doing something (i.e. it does not hang). You can use a single-line text-based progress bar for processing large lists of elements. It limits the progress output to a single line!

Level 2 should inform the user about what is being done in the background and especially why things do or do not work.

Please note that every function in maplab should have level 1 output at 1/30Hz informing the user about the progress. Using LOG_INFO() is prohibited everywhere, except in code that is part of an executable only. Penalty for violating this rule: http://helveticabold.tv/wordpress/wp-content/uploads/2010/03/09_fondue.jpg

You can start any application with verbosity level X like this: ./application --v=X