From the War and Health blog:

I am continuously impressed with UNOSAT’s ability to use satellite imagery in creative ways. On February 27th, UNOSAT released a satellite-derived estimation of the number of civilians leaving the Chadian capital of N’Djamena towards the Cameroonian border. The satellite photos are simply stunning. This is the first set of images I have seen capturing the epic scale of refugee flows. Each point on the photo is an individual and each yellow box a vehicle. The UN estimates that one photo contains 10,200 pedestrians and 80 vehicles.