[mapguide-users] EPSG:3857 Changes

[Greg]

Jackie,

Thank you for the reply.  I was able to create new dictionary files from the
source.  The source included the most recent version of the WGS84 Datum and
had been updated 7 months ago.  Using the new files didn't make any
difference.  My data requires a re-projection from UTM83-12 (NAD83 Datum) to
WGS84.PseudoMercator (WGS84 datum).  After a little more research, I learned
CSMap doesn't do any re-projection between NAD83 and WGS84.  Initially there
was no difference between the two and this made sense.  NAD83 isn't changing
much while WGS84 is moving as it is tied to the International Terrestrial
Reference Frame (ITRF), which changes over time.  ESRI has an article about
it here:

I think this may be the cause of my data not lining up with commercial
layers using the WGS84 Datum.  Until CSMap does a datum transformation first
and then coordinate translation, things will be a little off.

Thanks very much for your help.

Greg <http://support.esri.com/en/technical-article/000005929> 



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