Because the official: former National Geographic Institute "Geographical Service of the Army", which operates through our taxes for more than 80% remained in the Cassini map of the sixteenth century! Specifically, IGN does not use GIS (Geographic Information System) but continues to draw cards as time technical In terms of copper plates they say their sound card type "Raster" and it simply corresponds to French a digital image of the paper map. Garmin buys IGN raster maps and automatically vectorized with a type software "illustrator" The result is variable! To see what it is that a vectorized map to go to the source cadastre.fr and see the difference
