NavList:

To Frank Reed,

Thank you for replying to my message.

You wrote: "Did you try any sensitivity testing on your position solution?"

That's what I'm doing right now. Having to deal with three free parameters complicates the problem. I'm not only varying the latitude and the longitude of the viewing point but I also have to "adjust" the parameter for the scale of the photograph. I must admit that the solution is very sensitive to that scaling parameter. I find a nice fit moving 500m toward of away of the position I published when I change the scale of the image.  So there lies the limitation of my approach. If at least we knew the camera model and the lens focal length or if we had  a celestial object in the background like the moon it would gives us that scale factor and make the analysis more meaningfull. Or even better, knowing the position of the photographer.

Also, when I shift the image horizontally and vertically to match the vectors on the model, I know the alignment works in the horizontal plane because refraction is not a factor there but putting the top of the masts on top of the vectors (vertically) would be correct only if there were no refraction.

You wrote: "And did you try changing the radius of the Earth?"

Yes. Nothing changes visually on the graphic except that when I now measure distances, they are greater according to the greater earth radius. I found your explanation about refraction very interesting and informative.

Louis Carrier