[Qgis-developer] Georeferencing headeaches

[Maxim Dubinin]

not  necessarily, is there anything like *.wld or *.bpw file close to
your raster?

Вы писали 11 сентября 2011 г., 18:52:41:

AC> As far as I can tell, no. I'm aware that there are issues with a previously
AC> georeferenced TIFF, but I'm using a BMP and didn't think that this can store
AC> metadata.

AC> Andrew Chapman
AC> -----Original Message-----
AC> From: Maxim Dubinin [mailto:sim at gis-lab.info] 
AC> Sent: 11 September 2011 15:39
AC> To: Andrew Chapman
AC> Cc: qgis-developer at lists.osgeo.org
AC> Subject: Re: [Qgis-developer] Georeferencing headeaches

AC> Are you trying to georeference a raster that is already georeferenced?

AC>> I've used the georeferencer a number of times without difficulty (1.7.0,
AC>> Windows) on a number of occasions, but I've run into difficulties a
AC> couple
AC>> of times as described below.
AC>> I'm trying to georeference a BMP (4804 x 3084 pixels) using four points,
AC>> linear nearest neighbour transform and EPSG:27700. The message at the
AC> bottom
AC>> of the screen says "Transform:Linear Translation (399639, 182204) Scale
AC>> (2.10238e-06, 2.14539e-06) Rotation: 0 Mean error: 1.82928e+06".
AC>> The points file contains:
AC>> mapX,mapY,pixelX,pixelY,enable
AC>>
AC> 399725.746871799987275,182064.111945799988462,40058150.943396233022213,-1346
AC>> 0679.245283015072346,1
AC>>
AC> 399773.490492700017057,182058.143993200006662,62315320.754716999828815,-1767
AC>> 9358.490566037595272,1
AC>>
AC> 399756.519127400009893,182072.939542400010396,54779886.792452841997147,-1017
AC>> 3018.867924522608519,1
AC>>
AC> 399763.668237300007604,182090.781233999994583,58678528.301886811852455,-1997
AC>> 509.433962255716324,1
AC>> The mapX/Y values seem sensible, but the pixelX/Y values are far too
AC>> large... and shouldn't they be integers?
AC>> It generates the following world file:
AC>> 0.000002109413289
AC>> 0
AC>> 0
AC>> -0.000002133093642
AC>> 399641.036519734247122
AC>> 182094.590552107954863
AC>> The raster loads but is about 10mm wide rather than about 200m.
AC>> I'm not sure exactly why certain images are a problem, but am starting
AC> to
AC>> wonder if it is linked to trying to transform into a relatively small
AC> target
AC>> area.
AC>> Has anyone else seen this type of problem or is there anyone who can
AC> suggest
AC>> where I may be going wrong... or should I just file a bug report?

AC>> Andrew Chapman