You don't have to go high at all, you just need to take more percice measurements. Your eyes are really bad at spotting curvature of a 7926mile radius. FACT.
My photo. 84k feet. Slight fisheye, don't remember. No clue the fstop anymore. This was years ago for my senior project. Did all the calculations. On earth too.
"Ball earth argument"
All of physics, gravity, relativity and quantum mechanics is proof in of itself.