Hi Stewart, Thanks! I have just installed Quantum GIS (I'm running Ubuntu 10.10) and have loaded the JPEG as a raster file and am now learning how do do what you suggested.
Cheers, Peter Peter Freeman 180 Musgrave Place Salt Spring Island, V8K 1V5 British Columbia, Canada (250) 653-4623 http://members.shaw.ca/petersfreeman On 11-01-30 11:24 AM, Stewart C. Russell wrote: > Hi Peter, > > It's been a while since I hand-rolled a world file. If you can, install > a recent version of QGis, as it has a truly excellent georeferencer. You > click on control points on the bitmap, indicate the coordinates they > represent in the real world, then set the system off transforming the map. > > >> The map file is called map.jpg and I have created a world file called >> map.wld > I'd call that map.jgw, which is the convention for JPEG world files. > (TIFF has tfw, PNG pgw, and so on.) > >> 100.0 >> 0.0 >> 0.0 >> -100.0 >> 103.5 >> 1.5 > Ooh, that can't be right. Lines 1 and 4 are units/pixel; if you're using > geographic coordinates, that's 100°/pixel. This wants to be a small number. > > >> Can you give me reasonably correct values for my world file? > Lines 1 and 4 might want to be 0.01 and -0.01 respectively for 100 > pixels/degree. > >> Do I need to create a projection file > It helps, but these are even harder to produce by hand than world files. > I think that QGis can produce them in the georeferencer. > > Stewart > > _______________________________________________ > Talk-ca mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/talk-ca >
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