The startup Populace uses data from social media and other sources to display crowd densities at various locations across urban areas. As a result, the system could make it possible for journalists to find out automatically whenever an unusually large crowd gathers in a public place. We find out how it works from founder and Chief Executive Officer Chris Hawk.

Reporting by Lindsey Miller, Rachel Wise and Jessica King.

The Reynolds Journalism Institute’s Futures Lab video update features fresh ideas, techniques and developments to help spark innovation and change in newsrooms across all media platforms. Visit the RJI website for the full archive of Futures Lab videos. You can also sign up to receive email notifications of each new episode.

Main image CC-licensed by Flickr via Hsing Wei.