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Trying to manually create a worldfile for gif images of surface currents supplied by the navy here. I have QGIS and am decent at using it but the world file tool is failing without error on me (even after recompiling GDAL).

So I have both been manually calculating world files and using this website.

Repeatedly, I am coming up with the same numbers, but they can not be correct, at least not in the vertical. The resulting world file places the four corners in the correct spot, but pixels are incorrectly distorted in the vertical, and I believe it is only wrong in the vertical-see image of georeferenced TIF vs world file oriented GIF with Gulf lease areas for reference (those boundaries should not be on the coast). I have gone back to square one and georeferenced the source image several times, checked my calculations, and attempted to track down a QGIS expert to help get the tool working.

Can anyone help me generate the correct numbers for this world file?

What gets me is that I've been able to correctly do this for other images from the NRL site.... this one is just always slightly off.

enter image description here

Current (almost correct but at least line 4 is wrong) world file:
1) 0.02271210592255126
2) 0.00000
3) 0.00000
4) -0.02039280161507402
5) -98.38164194703873
6) 33.08804759959623

GCP file from QGIS if anyone wants a look: https://drive.google.com/file/d/0Bzky2_FkVtI9LXdrbjlENkc2N3M/view?usp=sharing

  • So you're saving them with the image file name and extension gfw? Does GDALINFO say anything? Why do you say line 4 is wrong? – Michael Stimson Feb 27 '15 at 2:30
  • QGIS seems to recognize the "gfw" or "jgw" extensions. Pretty sure that is not my problem. I say it is likely Line 4 because it is only incorrect in the y-direction/latitude. i tried attaching an image of a correctly referenced TIF image and the incorrect GIF via worldfile stacked on top of each other to show this. thanks! – WClark97 Feb 27 '15 at 2:51
  • And i got nothing from GDALINFO, in fact, it doesn't say the tool failed even-it's just that no files are ever created. Could there be a default file location I'm missing? I tried searching for ".wld" files and didnt turn up any deep QGIS locations. – WClark97 Feb 27 '15 at 2:53
  • There's an Esri discourse on world files resources.arcgis.com/en/help/main/10.1/index.html#//… which shows the parameters and naming convention... in this case Esri was there before GDAL so GDAL adopted the Esri standard. The world file should be in the same folder as the image or it wont be found. The file looks like it's coming up at/around -98,33 - how does this relate to real data like open street map? Is one of them right and the rest given the same numbers? p.s. our I.T. policy won't let me go to google drive, sorry I can't check out your link. – Michael Stimson Feb 27 '15 at 2:58
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    The leases are in NAD27, while I bet the Navy data is WGS84 or possibly NAD83. I don't think that would make a difference to the georeferencing (just one more difference to deal with), but... – mkennedy Feb 27 '15 at 18:24

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