[Qgis-user] Re: Projection of Shapefile export

[Giovanni Manghi]

Hi,


> But I can't make the parameters stick in the CRS of a vector file using the
> override facility. Any ideas?


if you use the +nadgrids parameter you must also include also the
+wktext parameter

example:

+proj=tmerc +lat_0=39.66666666666666 +lon_0=-8.131906111111112 +k=1
+x_0=200000 +y_0=300000 +ellps=intl +units=m +no_defs
+nadgrids=ptLX_e89.gsb +wktext


also, if you are reprojecting to a projected crs, the target crs must
include the +towgs84 parameter

example:

+proj=tmerc +lat_0=39.6682583333474 +lon_0=-8.133108333465099 +k=1
+x_0=0 +y_0=0 +ellps=GRS80 +units=m +no_defs +towgs84=0,0,0


The annoying thing is that every tool that allows reproject vectors
(example "save as...") does only let choose the target crs, so you first
have to save the vector in what need to be your source crs.

On the other hand the warp tool in the "raster" menu let the user choose
the source crs, so the transformation can be done in just one step.


cheers


-- Giovanni --