I have a query about this picture.
Ok, as we can see, half the buildings disappear and this is attributed to the curvature of the earth, right?
Well here's my problem with this.
If that is the case, we also are told that the earth is round, so it should curve from right to left but that line looks perfectly straight, yet my real query is.
If the buildings disappear by half, over that distance, then they should also angle away from each other, for instance, they should be slightly leaning left and right from that distance, also.
They may be spirit level straight up when your a mile away or a bit more, but not from that distance. Any reason why they are bolt upright, if the earth is a globe?
You're right, they should. But how much? Assuming each building is built perfectly perpendicular to the Earth's surface, than each should appear to another to be listing away just a little bit.
Let's calculate this list between the Willis Tower (second from left) and the camera. The distance is 74.3 km, or 0.0018557 times the circumference of the Earth. Multiply by 360° and we get a list of .668°. Since that list is directly away from the camera (it's leaning backwards) really the only indication this would be happening is it would appear shorter--3.6 cm shorter to be exact. Hardly noticeable at 74.3 km.
Now, the Willis Tower and the John Hancock Center (that's the tallest building on the right, number 10 from the left).
also list away from each-other, which, as you say, would be seen from the camera's perspective as them, well, leaning away from each-other. They are 2.4 kilometers apart, or .00005996 times the circumference of the Earth. Multiply by 360° for a total angular difference of 0.0216° or 1.3'. That means that the difference in the tops of a JHC parallel to the Willis Tower and the current JHC would be about 17 centimeters.
Once again, not noticeable at the 73.5 distance between the camera and the JHC.
So you're right that they should be tilted away from each-other and from the camera, but the tilt isn't visible on such a small scale. On a flat earth the Willis Tower would appear less than 4 cm taller, and the JHC would appear 17 cm closer to the Willis Tower. At this distance, such tiny variations are invisible.
Edit: For reference as to what a JHC 17 cm closer to the Willis Tower would look like, the width of the JHC visible from this photo is about 32 meters, making each pixel about 10 meters wide. The tilt away would be about 1/10th the width of a pixel. In other words, undetectable.