How to Take a Far Screenshot

I recently finished a custom terrain and I would like to know how to take a screenshot that can view a huge space. In case you don't understand what I mean, take a look at the first picture on this project on that is what I mean. I know that there is probably a program for this but I need some steering in the right direction. Sample Picture: http://www.planetminecraft.com/project/ ... ntasy-map/