Is this correct that if a table is in Lat/Long projection with no datum
associated in the projection list , MI will imply that it is in NAD27 and
recalculate the coordinates from Nad27 to the new selected projection? I always
assumed that if data is in Lat/Long with no datum selected in the projection
list, and if and when a new map projection is set it will not change or
recalculate anything but simply associate that newly selected datum to that data
set. Then if you decide to change the projection after that then it will
recalculate the coordinates to a new projection. I'm I wrong, can someone clear
this up for me?
TIA
Dan
"Robert Crossley" <[EMAIL PROTECTED]> on 06/01/2001 03:12:31 PM
Please respond to "Robert Crossley" <[EMAIL PROTECTED]>
To: "MapInfo List" <[EMAIL PROTECTED]>
cc: (bcc: Dan Page/HullOttawa/PCH/CA)
Subject: SUMM: MI-L Problems with WGS 84 projections in a
map display
Thanks to Willy from Denmark for advice on this one:
>>
I have found that you should never, ever use the Lat/Long without datum.
Apparantly MI being an US application then thinks that it implies, that the
NAD 27 was used in calculation of the coordinates. So if no datum is
specified even if the coordinates are to e.g. WGS84 MI will recalculate the
coordinates from NAD 27 to WGS 84 if the map projection is set to WGS 84
giving an error of several hundred meters.
I am still working on it, but this seems to be the key.
Sorry Dave, your answer was not correct and you must leave now.... Thanks
anyway.
Robert.
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