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 Problems with .ecw World Image file

John Woodall's profile image
John Woodall posted 12-12-2025 05:19

I have received an image from the mapper on a roadway project that gives me the following error on import. I am in South Carolina which uses International Feet and all my settings are set to Ift. The image also does not match the linework provided by approximately 3.90' which is about what you would get conversion between the Ift and USft.

does anyone have an idea about a setting i may have missed. I am not drawing from the image just using it a reference but the warning and offset is driving me nuts.

ian bissonnette's profile image
ian bissonnette

try importing to a blank project that is set to international feet. see if that clears the warning. if this is the problem then convert or get an image with the right settings. 

or scale it, or align to known points is likely the fastest. 

Zach Edwards's profile image
Zach Edwards

I would guess that it's not the differences between ift or sft, but rather a datum shift. Whether using Civil 3D or Microstation, be sure to use the NSRS11 (Nad83 2011) datum and realization. I see so many folks still use the legacy Nad83(86) in Civil3D. Also, Ian's suggestion of aligning/georeferencing the image in TBC would be a quick fix as well. 

Erik Petersen's profile image
Erik Petersen

If you have GCPs I think georeference the image to the spots to adjust it.

ian bissonnette's profile image
ian bissonnette

thinking about this more, i think that zach is likely right. it is more likely a coordinate system issue. i notice that a lot of uav data is in wgs84. this can be nice because it avoids identifying what projection projects are in. but i have also seen that some uav data is in wgs84 but not lat longs (the error is showing that tbc is looking for global lat longs), and instead the uav data is in wgs84 grid (northing easting). this is a little confusing, but it seems like some gis software is ok with this. i don't fully understand how it is projected, but i believe some of the software uses a wgs84 projection, maybe others could chime in what is happening there. but we have had a hard time making a coordinate system in tbc to mirror this. this warning makes me think this is the case, if there is an associated file with the image you might be able to see for yourself and even convert it. around here, wgs84 to a utm system is about 1.2m which is pretty much what you are seeing. 

i would disagree with zach about his descriptions about datums. there should be no right or wrong datum as long as you are consistent with your project and client needs. but yes, moving to more current datums would be nice(and a pain if you have historic projects).