I have a geodatabase with feature classes projected with WKID:27561 NTF_Paris_Lambert_Nord_France. I wanted to
use these features in Arcgis online. I transformed them to WGS84 using the Arctoolbox, zipped them into shapefiles and imported them into Arcgis online. They worked perfectly on the basemap and the distance between point features was correct. When I downloaded the same shapefiles and opened them in Arcmap the distances were off by 30%.
I tried selecting a projection for the data layer but with no luck. What makes the ArcGis online accurate when Arcmap is not? Thanks in advance