You can make the black surrounds to your warped image transparent by
right clicking on the layer, choosing properties, then selecting
Transparency. Add a new entry to the Transparent Pixel List using the
button with the star, then put 0 in for Red, Green and Blue (or 255 for
white backgrounds).
Roland
[email protected] wrote:
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
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