Am 23.10.2014 um 08:51 schrieb Nadarajah Thirugnanasothy:
I was trying to help someone and had similar problem with two sets of
vector data. Tried all these methods and failed.When I searched the
net to find an answer, I found many people have similar problem.What
about some one actually showing how to do this with a data set and
posting it as a tutorial (with screen shots) some where. I do not
have the data set that I was playing with. Thank youThiru(I am 70
years old & retired now. Had used ESRI/ArcView & Arc Info about 10
years ago )
Unfortuantely, there is no easy way to discover the reasons for not
overlapping.
If it is about 100m, this is most likely a datum shift issue.
Google/Web Mercator datasources may shft to about 20km vertically if the
transformation method is wrongly implemented (like EPSG:3395).
If the images are totally off, most probably projection definitions have
been simply exchanged instead of doing a correct coordinate
reprojection. Comparing the layer extent is the best to sort this out.
HTH,
André Joost
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