[gdal-dev] Re: Thin Plate Spline

Jukka Rahkonen jukka.rahkonen at mmmtike.fi
Tue May 4 09:08:28 EDT 2010

Jan Hartmann <j.l.h.hartmann <at> uva.nl> writes:

> you can see a screenshot of the original image (right) and the 
> georeferenced one (left, rotated almost 90 degrees). The red markers 
> with the number 3 inside them show one of the control points: to the 
> right the scan pixel  (5023/3421), to the left the targeted 
> georeferenced coordinate in EPSG:28992 (121527/487174). As you see, the 
> georeferenced point is not exactly on the border of parcel 7, as I 
> expected. Above the map you see the four coordinates I used as control 
> points; I added four extra points half way the original ones, so the 
> complete warp was done with 8 control points.


I can try to repeat your test some day. Is this your workflow:

1. gdal_translate -of VRT -gcp p1 l1 e1 n1 -gcp p2 l2 e2 n2 -gcp p3 l3 e3 n3
   -gcp p4 l4 e4 n4 -gcp p5 l5 e5 n5 input.tif temp_with_gcp.vrt

2. gdalwarp -s_srs EPSG:28992 -t_srs EPSG:28992 -tps temp_with_gcp.vrt warped.tif

3. Measure the coordinates of the ground control points from warped.tif 
   with some GIS software like QGis and find out disappointed that 
   they have shifted.

-Jukka Rahkonen-

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