Accuracy Assessment

Reference Data

Accuracy is checked against randomly selected map pixels. Because field visits are expensive and some sites are inaccessible, reference data combine ground referencing surveys with aerial photographs and high-resolution satellite imagery such as Google Earth. For the 2018 map, 3,649 points were verified this way.

For the 2018 map, 1,894 sample points were visited in the field, chosen by accessibility and security, and 1,905 more were interpreted independently on Google Earth high-resolution imagery. Historical maps could not be visited, so they were checked against Google Earth imagery.

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