Bug report #523

Georeference tool

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

Status:Closed
Priority:Low
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

Description

Tried to georeference a jpeg image to EPSG 32119 projection. The output jgw file looked like this:
24.5335
0
0
-24.5335
nan
26052543469100656972793667356933792334551124445385671982001717765625696361250852
63230640588410366355387916037395507101170807331933447168232048026256148650314170
68255704400035347073092961720361697046386861456890565381992582038014706635298444
962359964072945413053455317431577487218906213975588864.000000
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:
24.4658442217
0.0000000000
0.0000000000
-24.4658442217
526378.6525011690
167601.3482739714

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

History

#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:
24.6106913661
0.0000000000
0.0000000000
-24.6106913661
526364.0265134282
221911.9794584604

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

Thanks!

#8 Updated by Anonymous about 11 years ago

Milestone Version 0.8.1 deleted

Also available in: Atom PDF