Georeference tool

[doug_newcomb@…]

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.

[homann]

Is it possible to supply the image?

[doug_newcomb@…]

points file generated on jpeg file

[doug_newcomb@…]

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

[homann]

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?

[doug_newcomb@…]

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?

[homann]

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

[homann]

Fixed in r6509 / r6510. Uninitialized variables made win32 behave differently.

[doug_newcomb@…]

Thanks!

[(none)]

Milestone Version 0.8.1 deleted