[Qgis-developer] Georeferencing headeaches
andrew.chapman at donkagen.co.uk
Sun Sep 11 10:18:26 EDT 2011
I've used the georeferencer a number of times without difficulty (1.7.0,
Windows) on a number of occasions, but I've run into difficulties a couple
of times as described below.
I'm trying to georeference a BMP (4804 x 3084 pixels) using four points,
linear nearest neighbour transform and EPSG:27700. The message at the bottom
of the screen says "Transform:Linear Translation (399639, 182204) Scale
(2.10238e-06, 2.14539e-06) Rotation: 0 Mean error: 1.82928e+06".
The points file contains:
The mapX/Y values seem sensible, but the pixelX/Y values are far too
large... and shouldn't they be integers?
It generates the following world file:
The raster loads but is about 10mm wide rather than about 200m.
I'm not sure exactly why certain images are a problem, but am starting to
wonder if it is linked to trying to transform into a relatively small target
Has anyone else seen this type of problem or is there anyone who can suggest
where I may be going wrong... or should I just file a bug report?
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