I want to use this proj4 code:
+proj=utm +zone=19 +ellps=WGS84 +toclrk66=-3,142,183,0,0,0,0 +units=m +no_defs
or this one:
+proj=utm +zone=19 +ellps=WGS84 +tonad27=-3,142,183,0,0,0,0 +units=m +no_defs
to make on the fly transformations from WGS84 to NAD27, using the geocentric tanslation parameters recommended for Dominican Republic. I typed this codes using the "New CRS" capacity in QGIS 2.0 (Configuration>Custom CRS), but it doesn't accept the transformation parameters. After typing the codes, and pressing OK, the CRS created looks like this:
+proj=utm +zone=19 +ellps=WGS84 +units=m +no_defs
QGIS deletes the geocentric traslation parameters. Maybe I'm violating proj4 codes rules, and that's why I'm asking for help.
Best Answer
The layers are in WGS84, and the project CRS is NAD27 UTM 19 North.
I am not 100% sure this will work, but the convention in PROJ.4 for 3 and 7 parameter transformations is to use
In the project properties, CRS tab, PROJ.4 text box, enter this definition:
+proj=utm +zone=19 +datum=NAD27 +ellps=clrk66 +towgs84=-3,142,183,0,0,0,0
If it doesn't appear to be working, try dropping the +datum=NAD27 option.