[Rama Set]

I meant 25,000 miles... But anyway, what does the shape of earth have to do with viewing distances? The perspective effect would be the same and that chart has no mention of curvature at all. One thing round earth fails to rectify is the fact the horizon is always level center no matter how high you go. At no point do you look down to see it. Any computer simulation of a sphere, no matter how big, and a rising camera results in the "horizon" dropping.

The horizon appears at eye level when you are looking at it, because the visual accuity of humans is not very sophisticated.  However, if you were to use a theodolite, you would measure that the horizon is indeed below "eye level".

For example, the distance to the horizon if you are viewing from 2m in height is 5 kms.  At 5kms, the amount of drop in the curvature is approximately 0.5m.  If we solve a right-angle triangle for the angle between the 5km length and the .0025km drop, we get an angle of 0.03 degrees, which is barely perceptible to the human eye and would likely only be visible with the aid of instruments.

[rabinoz]

I meant 25,000 miles... But anyway, what does the shape of earth have to do with viewing distances? The perspective effect would be the same and that chart has no mention of curvature at all. One thing round earth fails to rectify is the fact the horizon is always level center no matter how high you go. At no point do you look down to see it. Any computer simulation of a sphere, no matter how big, and a rising camera results in the "horizon" dropping.

So many flat earth supporters say:

"One thing round earth fails to rectify is the fact the horizon is always level center no matter how high you go. At no point do you look down to see it."

But has anyone tested that out?
On a hill of 1000' on a globe the horizon is only 0.49° below true level! You would never discern that by eye and like it or not at that altitude we could have some refraction.
Even at an altitude of 30000' the horizon is still only 2.7° below true level! Out of a plane window that would not be noticeable by eye. You would need some level reference to demonstrate it. Here I don't think refraction either way will bother the measurement much.

The video below (has to be played in Youtube) is not exactly on topic and is a bit long, but is worth watching.
It is from a Geodetic Surveyor describing surveys across the USA covering around 400 years, long before NASA and ideas of a Flat Earth.
He describes run of surveying measurements that clearly measures the curvature of the earth. Of course, surveyors have a big advantage over the rest of us in that they can measure angles (vertical and horizontal) to a very small fraction of a degree.

https://www.youtube.com/watch?v=U2xneYENfdg

I don't know why, but for me the video starts near the middle, though that is probably the most relevant. The early part introduces who the surveyor is and does give some insight on why we cannot "see" the curvature.