I am using ArcGIS 10 and trying to work in British National Grid.
My shapefile is in WGS84 UTM30N.
I passed the shapefile across to a colleague and we both transformed into BNG.
When we compared the data there was a significant difference in our results.
I have since cross-checked with QGIS, Global mapper and a website or two and got a whole range of results but in general the most common is the result my colleague got.
- What have I done wrong?
- Why is there such a variation (~150m) in values? (1 or 2m error is probably ok for what I am looking at.)
- Which value is "right"?