[OSRS-PROJ] NTv1 (Canadian) Grid Shifts, and proj_def.dat

Frank Warmerdam warmerdam at pobox.com
Thu Apr 5 15:11:20 EDT 2001


Two items.

First, I have modified nad_init() to support loading of Canadian NTv1
grid shift files which are free to use, though lower precision than the
expensive NTv2 grid shift files.  Anyone interested in testing this is
encouraged to contact me. 

Second, I would like to change proj_def.dat to provide a default ellipsoid
of WGS84 (really would make it +datum=WGS84).  The assumption is that in
this day and age WGS84 is a better default than clrk66 (normally NAD27). 
What are peoples opinions on making this change?  Obviously it could 
cause some problems, but I have been bitten a number of times by the 
implicit appending of clrk66. 

Best regards,

I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent
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