Horizontal_Positional_Accuracy_Report:
The images used to produce this atlas have a resolution of 30 m. On top of
this, a 3 x 3 majority filter has been applied giving a ground resolution of 90
m. If this represented 1 mm on a scale map then it would be possible to use
the vegetation map at a scale of 1:90 000, which gives us a quality scale. The
actual accuracy (i.e. how close the map boundaries are to the reality on the
ground) is dependent on the ortho-rectification of the original Landsat
imagery. The recommended useful scale for Landsat imagery is set at a
minimum of 1:125 000. It should be noted that at higher elevations the georeferencing
will tend to be worse. In the field we observed errors of ~ 150
meters for some areas of high elevation (Ambohitra at ~ 1 400 m), but no
significant errors were observed for lower elevations. With all this in mind it
would be possible to push the data to a scale of 1:125 000, but a good
working scale would be 1:250 000. See MADAGASCAR VEGETATION ATLAS - Editors: Justin Moat and Paul Smith, publisher Royal Botanic Gardens, Kew. Probable Publication date Sept 2007.