[Qgis-developer] Georeferencing headeaches

[Maxim Dubinin]

for  the  sake of experiment, try opening and saving your bmp in the graphic
editor   like  GIMP under different name and format (say TIF), load in
georeferencer. Will you still have projected coords?

Maxim

Вы писали 11 сентября 2011 г., 21:54:44:

AC> There was a .WLD for a file with a different name - I deleted it, the points
AC> file... and tried again. No improvement.
AC> The points have figures like srcX = 32749572.45. Given the source image is
AC> only 4804 x 3084 pixels, why would I get a value four orders of magnitude
AC> greater than the pixel count? 

AC> Andrew Chapman

AC> -----Original Message-----
AC> From: Maxim Dubinin [mailto:sim at gis-lab.info] 
AC> Sent: 11 September 2011 15:59
AC> To: Andrew Chapman
AC> Cc: qgis-developer at lists.osgeo.org
AC> Subject: Re: [Qgis-developer] Georeferencing headeaches

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

AC> 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
AC> previously
AC>> georeferenced TIFF, but I'm using a BMP and didn't think that this can
AC> 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
AC> (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
AC> 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>>
AC> 399725.746871799987275,182064.111945799988462,40058150.943396233022213,-1346
AC>>> 0679.245283015072346,1
AC>>>
AC>>
AC> 399773.490492700017057,182058.143993200006662,62315320.754716999828815,-1767
AC>>> 9358.490566037595272,1
AC>>>
AC>>
AC> 399756.519127400009893,182072.939542400010396,54779886.792452841997147,-1017
AC>>> 3018.867924522608519,1
AC>>>
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


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