[Qgis-user] Re: Qgis-user Digest, Vol 48, Issue 36

[Carlo A. Bertelli (Charta s.r.l.)]

Hello Darren, Maxim and List,
I use the georeferencer extensively for historical maps and I
appreciate very much the new plugin.
I also think this mail exchange is very useful; I would ask even more
for the georeferencer to be great for historical maps.
To use them in historical GIS, we try to find old buildings or
significant features on ground, usually corner points carry no useful
information.
It would be very beneficial for our work to "see" the reference points
on the map canvas as a sort of temporary layer qnd even to be able to
move the target points instead of the points on the image. To ask
more, it could also be useful to save the (named) GCPS as a layer for
further reference (or "operation"). The idea behind this is that an
old survey or plan could perfectly "fit" a certain area and badly
"fit" another, so we could need switching between two or more
georeferences.
About the seemingly not substantial issue of backgroundm I may suggest
grey as a good background because white may lose the edges of white
maps, black would hide borders of precisely cut ones, grey maps are
usually brown more than grey.
Do I ask too much?
TIA
Carlo

On Thu, Feb 18, 2010 at 6:01 PM, Maxim Dubinin wrote:

> Hi Darren,
>
> hmm, we're currently using new Georef intensively for referencing
> literally hundreds of rasters to create Geotiffs.
>
> It is not clear from the description of the first problem, whether you
> cannot create Geotiff at all, or the problem is in "incorrect"
> extension? We removed creation of wld in new Georef file as it is not really needed
> when you generate Geotiff. This might be a good idea to return it
> in options.
>
> Please check out this small video as a proof that it indeed works for
> referencing using corner points:
> http://screencast.com/t/Mzk4NWZlNz
>
> Regarding 2, I agree, this would be nice to be able to set.
>
> Please open bug/feature requests on trac with clear explanations, if
> you're still unable to make it work and suggested functionality.
>
> Maxim
>
> DC> - I am unable to get it to output a geotiff file.  Even when the "Output
> DC> Raster" is set to GeoTiff (the only option) it will write out only a .wld
> DC> file.  This then needs to be renamed to the appropriate extension (e.g. I
> DC> was using a .png input, so had to rename .wld to .pgw)  The pluging should
> DC> create the appropriate world file type based on the output file, or actually
> DC> write a Geotiff when it says it will
> DC> - the Georeferencer background is now white.  This is not ideal when trying
> DC> to find the corners of a white image.  I often georeference images based on
> DC> corner points, and was able to do this easily in previous versions.  Perhaps
> DC> an option for background colour, or set it back to black by default?
> DC> - A question--what will the "link Georeferencer to QGIS" and "Link QGIS to
> DC> Georeferencer" buttons do (once they are operational?)
>
> DC> I realize this is still under active development, so hope these issues are
> DC> being fixed/considered.
>
> DC> Cheers,
>
> DC> Darren