I recently came across this great idea for validation of Land Cover data to improve global land cover maps. The Geo-Wiki Project allows volunteers to review and validate land cover by looking at Google Earth images and determining whether the classification is correct or not, based on visual interpretation and/or local knowledge. The plan is then to use this data to create an improved global landcover dataset.
There’s also a “game” that shows you an image and asks whether or not there is cropland in the image. It’s very simple and apparently the answers in the game are also recorded in a database (even though you get corrected if you give the wrong answer). You can even win prizes if you validate a lot.
In the larger perspective, this data is expected to fill enormous gaps in our knowledge about croplands around the world that essentially will help “tackling problems of future food security and the effects of climate change on future food supply”.
The game is to be found here, just sign up and start validating!