To do this, they basically went through archives of satelitte imagery and on a pixel-by-pixel basis assembled a map that is essentially cloud free.
Starting today we are excited to offer MapBox Cloudless Atlas as one of the core basemaps avaiable on formhub. This joins the existing MapBox Streets base layers - Open Street Map powered and available in English, French and Spanish.
Since formhub is used extensively by many groups for mapping. We hope this new, clearer picture of the world will help extra insight to your data.