Trees, forests and land use in drylands: The first global assessment. Conducted using Open Foris Collect Earth

The Food and Agriculture Organization of the United Nations (FAO) Global Drylands Assessment is a thematic study based on the visual interpretation of satellite images in publicly available repositories (such as Google Earth Engine and Bing Maps) focusing on drylands. Results are reported at the global and regional levels. More than 200 experts with knowledge on land uses in specific dryland regions conducted the interpretation using the Open Foris software tool Collect Earth. 

Collect Earth communicates with Google Earth Engine to facilitate access to freely available satellite images from Earth Engine, and it can also connect to other services, such as Bing Maps. Collect Earth enables operators to visually assess pre-defined sample locations and to store the results directly in a database by completing an onscreen data-collection form.

For the Global Drylands Assessment, the data-collection form was structured to guide operators in the survey process, starting with the identification and quantification of simple land elements and the identification of the main land-use categories. Collect Earth projected each sample plot as a frame containing a grid of 49 control points, enabling users to make precise estimates of the proportion of plots taken up by trees, shrubs and other land elements. In the visual interpretation, each expert used his knowledge of the location and information provided by remote sensing data to support the survey process.