Aug 9, 2010 by Zhe Guo

The travel time maps indicate the degree of accessibility from a pixel to a populated place. The patterns shown here describe the geographic accessibility between places in Sub-Saharan Africa. We define accessibility as the time in hours required to travel from a given single point (1x1km pixel) to the nearest market center. Travel time to market centers is used as a proxy for market accessibility and shows the likely extent to which farming households are physically integrated with or isolated from markets.


Aug 8, 2010 by Zhe Guo

Global human settlements database comprises a global dataset of about 55,000 cities and towns with populations of 1,000 or more.