There's probably pretty good reason this specific bit went open source. The vision tracking community usually tends to make leaps and bounds on open source projects. People will easily be downloading openCV and modifying it in different ways for their home projects. These modifications will then be usefull to darpa.
Considering that the vision tracking isn't a core function of one of their devices they probably aren't as interested in hoarding it. Why not let some other people do the work?
Drones are, in essence, flying autonomous vehicles. Pros and cons surrounding drones today might well foreshadow the debate over the development of self-driving cars. In the context of a strongly regulated aviation industry, "self-flying" drones pose a fresh challenge. How safe is it to fly drones in different environments? Should drones be required for visual line of sight – as are piloted airplanes? Join EE Times' Junko Yoshida as she moderates a panel of drone experts.