[Qgis-developer] Enhanced georeferencer plugin

[Rahkonen Jukka]

Hi,

Great, that was fast!  I have a few scanned historical maps which I have not yet warped with the manual way so I will for sure test the plugin immediately when I can get it for Windows.

-Jukka Rahkonen-


> -----Alkuperäinen viesti-----
> Lähettäjä: Maxim Dubinin [mailto:sim at gis-lab.info] 
> Lähetetty: 4. helmikuuta 2009 18:08
> Vastaanottaja: Rahkonen Jukka
> Kopio: qgis-developer at lists.osgeo.org
> Aihe: Re: [Qgis-developer] Enhanced georeferencer plugin
> 
> Dear Jukka,
> 
> this functionality is already implemented in new Georeferencer plugin.
> You can grab a copy for Ubuntu from svn mentioned here [1] or 
> wait for new 1.0.1 (?) release of QGIS, where it will be part 
> of standard distribution.
> 
> http://gis-lab.info/qa/qgis-georef-new-eng.html
> 
> Meanwhile, we'll be glad to hear from you regarding any 
> problems with this plugin.
> 
> --
> Best regards,
>  Maxim                          mailto:sim at gis-lab.info
> 
> Вы писали 4 февраля 2009 г., 7:07:52:
> 
> RJ> Hi,
> RJ> This message has been lying for some days in QGis forum and now I 
> RJ> was adviced to send it to mailing list.
> RJ> -Jukka Rahkonen-
> RJ>  
> RJ> Forum message follows:
> RJ> "The Georeferencer plugin is pretty nice to use. However, I have 
> RJ> found that the result of georeferencing with world file is not 
> RJ> always satisfactory. Therefore I have used the fine user 
> interface 
> RJ> for collecting ground control points and done the rest of 
> RJ> georecerencing with other tools. However, I believe that 
> it should 
> RJ> be rather easy to modify the Georeferencer plugin so that 
> it could 
> RJ> do georeferncing also with this alternative way. As a result QGis 
> RJ> would have a georeferencing tool of professional quality 
> both when 
> RJ> it comes to easy of use and accuracy.
> RJ> The work flow would be like this:
> RJ> 1. Ground control points are collected with the existing plugin.
> RJ> It is gathering all the information that is needed for 
> the next step 
> RJ> (mapX, mapY, pixelX, pixelY) 2. Ground control points are fed for 
> RJ> gdal_translate program as -gcp parameters. Gdal_translate 
> takes them 
> RJ> in this order:
> RJ> [-gcp pixel line easting northing [elevation]]* The whole 
> RJ> gdal_translate command line would be gdal_translate -of 
> GTiff -gcp 
> RJ> [params_1] -gcp [params_2] -gcp [params_3] .... input.tif 
> RJ> temporary.tif 3. Third step is to warp the temparary image that 
> RJ> contains now the ground control points. It is done with gdalwarp, 
> RJ> for example like this:
> RJ> gdalwarp -of GTiff -s_srs epsg:4326 -t_srs epsg:4326 
> temporaty.tif 
> RJ> warped.tif Command lines are presented as working 
> examples which can 
> RJ> be repeated with gdal utility programs. For the plugin it 
> would be 
> RJ> better to call gdal funtions directly, use virtual raster 
> format as 
> RJ> temporary format instead of tiff etc. I cannot say very 
> much about 
> RJ> how it should be done because I can't program myself.
> RJ> However, in the very end of this link 
> RJ> http://www.scangis.org/scangis2007/papers/r3_rahkonen.pdf 
> there is 
> RJ> python code that might be useful and that can be used 
> freely. That 
> RJ> script is doing basically the same thing, it takes ground control 
> RJ> points from external source and warps image automatically 
> with gdal components."
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> 
>