Bug report #523

Georeference tool

Added by doug_newcomb-fws-gov - over 13 years ago. Updated about 11 years ago.

Assignee:Magnus Homann
Category:Projection Support
Affected QGIS version: Regression?:No
Operating System:Windows Easy fix?:No
Pull Request or Patch supplied: Resolution:fixed
Crashes QGIS or corrupts data: Copied to github as #:10582


Tried to georeference a jpeg image to EPSG 32119 projection. The output jgw file looked like this:
The qgis - generated points file :

mapX mapY pixelX pixelY
551629.000000 119426.000000 1042.95 -1942.69
558297.000000 128803.000000 1320.27 -1560.28
561736.000000 142243.000000 1460.38 -1023.16
554963.000000 154641.000000 1185.99 -519.606
532042.000000 159226.000000 234.348 -329.862
539335.000000 147557.000000 536.478 -807.141
529333.000000 124635.000000 132.178 -1723.75

I converted the above y pixel coordinates from negative to positive and used the altered coordinates as gcp points in gdalwarp and got the following correct world file:

My simplistic assumption is that the qgis georeferencer is passing negative y coordinates for a jpeg file when they should be positive instead.

PE_rockingham_westend.jpg.points - points file generated on jpeg file (339 Bytes) doug_newcomb-fws-gov -, 2007-01-29 07:05 AM


#1 Updated by Magnus Homann over 13 years ago

  • Status changed from Open to In Progress

Is it possible to supply the image?

#2 Updated by doug_newcomb-fws-gov - over 13 years ago

Tried to add the original jpeg file, but was too large at 3.2 MB

#3 Updated by Magnus Homann over 13 years ago

We had some issues where if proejction was turned on when you entered georeference tools, it wouldn't work. have you tried turning off projection?

Also, if you have the possibility try downloading the latest from SVN and try it there. I have done some work with it.

If this does/does not work, let me know. There is nothnig bad with negative coordinates as I see it (0,0) is upper left pixel according to world file specification. What happens if you use gdalwarp with the negative coordinates?

#4 Updated by doug_newcomb-fws-gov - over 13 years ago

I can go back and check, but I as I recall using negative line numbers with GCPs caused the image to flip upside down. ( I had tried it with a tiff version of the file as well)
the world file associated had the following contents:

With a negative y pixel size

I thought image specs in general had the 0,0 in the upper left hand corner and positive x going right and positive y going down?

#5 Updated by Magnus Homann over 13 years ago

The points in the .points file are in an internal format, and we do not use GDAL to generate world file. Have you tried to turn off projection?

See also #560

#6 Updated by Magnus Homann over 13 years ago

  • Status changed from In Progress to Closed
  • Resolution set to fixed

Fixed in / . Uninitialized variables made win32 behave differently.

#7 Updated by doug_newcomb-fws-gov - over 13 years ago


#8 Updated by Anonymous about 11 years ago

Milestone Version 0.8.1 deleted

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