I have a lot of tif files (ortho imagery that came with Lidar data). Each tile has a .tif and .tfw but the world files (.tfw) have line 5 and 6 as numbers that aren't what I would expect as I was expecting the files to be in UTM ZONE 10.

Is there anything I am missing that usually comes with Ortho Imagery / Lidar? Or do I need to contact the supplier and ask them to re-export as a geo-referenced file. Or maybe this is just coordinates on a local site datum and that is it.

Below is an example of on the of the world files. The list number is the line number.

  1. 0.200078983
  2. 0
  3. 0
  4. -0.200078983
  5. -1813.10469
  6. 4172.72779

I guess the question is can you have ortho-rectified imagery on a local site datum? I thought maybe it would have to be real-world coordinates?

  • 1
    It does look like a local datum, too small for UTM but not small enough for DD. What happens when you separate the tif from the tfw files? It is possible that they are different. Is 20cm correct for you pixel size? – Michael Stimson Sep 10 '15 at 4:34
  • 20cm is correct.I seperated the file and brought into Arcmap. Still small numbers and not in the correct space. I edited the original question to summarize my knowledge gap about local site datums and ortho imagery. – badgerseatfrogs Sep 10 '15 at 4:39
  • Ask for resupply, if you specified georeferenced imagery in your contract then something has gone wrong with the orthorectification... it should be a simple fix. If you can get the offsets from their current location to the correct location you can apply the Shift tool to move them to where they're supposed to be help.arcgis.com/En/Arcgisdesktop/10.0/Help/index.html#//… – Michael Stimson Sep 10 '15 at 4:42
  • Ah I see. I'll do this, it's come second hand but i'll ask. Do I have to get the offsets - there is no way of calculating these? – badgerseatfrogs Sep 10 '15 at 4:53
  • 1
    You can have a good guess if you can find a point that is obvious and you know the exact location of, find the difference between the known coordinate and the raster coordinate and that should give you the values for X_Shift and Y_Shift - that is assuming the images don't need further rotation. If (most likely) all the images need to be moved by the same then they can be batched with a python script.. do you have any python experience? – Michael Stimson Sep 10 '15 at 5:00

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