[Qgis-user] Re: georeference plugin, maximum distortion needed, and black background

[mtnbiketrail at zzz.com]

I'm trying to geo-reference some rasters.
I'm not sure which algorithm to use to get maximum match with known 
GCPs, these rasters need to be distorted a lot. I thought tps and cubic 
would be best. Can anyone tell me which algorithm is best?

Also, when the raster is placed(georeference completed), the background 
outside the original raster is black, not transparent like I would 
expect. I doubt I can trim the modified raster without losing GCPs. I 
can make the raster transparent, but I don't like the results.  Is there 
a solution to the black background?

Once I am satisfied with geo-referenced rasters, I can trace vector 
polylines inside QGIS. Or is there a better way? Using a vector drawing 
program like Inkscape or Adobe Illustrator?

I'm potentially dealing with a lot of data, so am looking for the best way.

thanks,
Tom
using 1.3