[OSM-talk] Georeferencing images WAS ping OpenAerialMap

[Jukka Rahkonen]

David Groom <reviews <at> pacific-rim.net> writes:
> > From: "andrew" <list <at> sylva.icuklive.co.uk>

> > I've some aerial photos that I need to find how to georeference, 4MB 
> > jpegs and 17 overlapping tiles, is there a program you can 
> > recommend?
> > 
> > Andrew Heggie
> > 
> 
> How about Quantum GIS with the georeferencing plugin  http://www.qgis.org/
> 
> David

Hi, 

I made a quick test with Quantum GIS (version 0.10 "Io") georeferencing plugin.
It was pretty easy to use.  Coordinates can be given manually or then can be
captured from a map window showing existing map, image or WMS layer. However, at
least the version I used can only calculate the place for origo and pixel size
in x and y directions.  The plugin does not do warping nor rotating.  Therefore
it is only usable if the image to be georeferenced is not rotated nor distorted.
It is OK if the map or image is captured from the web (for example by using the
OSM Export utility) or scanned carefully without rotating the original.

Good thing is that the ground control points are automatically stored into text
file with real world and pixel coordinates. That way QGis can be used as a GUI
for measuring GCPs for gdalwarp.