[GRASSLIST:7944] nad27/nad83 datum conversion for canada using Ntv2

[Feng Tan]

Hi, List,

1.) I want to do datum conversion for Canada using Ntv2 grid file, how should 
I set up the locations for them? It seems grass6.0 only use Ntv1.data grid to 
set nad27 datum for canada (no option to use Ntv1.dat for nad83 datum), but 
Ntv2 version is more accurate grid shife file, how can I apply Ntv2 grid file 
for both nad27 and nad83 locations?

2.) If I use cs2cs to do the conversion for canada, what is the procedure for 
applying Canadian NTv2.gsb grid file? 

3.) Did anybody evaluate the converted coordinate accuracy between last 2 
methods in GRASS6.0, or against other softwares such as ESRI and FME? What 
the outcome? Do they get the same results?

Thanks,

Feng