1080p gopro fisheye flat earth sagitta perceived pixel curvature 1920 lens curvilinear rectilinea..

what percentage earth must be visible to show 2 pixel curvature in 1920×1080 = .0009765625 % vs barrel distortion.
why do all flat earthers obsessively lie about water being flat?
do you need to get to around 60,000 feet to be able to clearly discern the curvature of the earth or 35,000 to have any chance of detecting it.
there's lots of photos on a daily basis from satellites in high orbits that show the full disk of the earth

http://rammb.cira.colostate.edu/ramsdis/online/himawari-8.asp
https://www.metabunk.org/folsom-lake-photographs-demonstrating-the-curvature-of-the-earth.t7789/
https://flatearthinsanity.blogspot.com/2016/08/flat-earth-follies-high-altitude.html
http://thulescientific.com/Lynch%20Curvature%202008.pdf
http://metabunk.org/are-lynchs-horizon-calculations-correct.t7877/
http://metabunk.org/earth-curvature-refraction-experiments-debunking-flat-concave-earth.t6042/page-6

the ACTUAL answer for the altitude = sea level or a BIG lake shore

set up a sight stick at 4 or 5 feet, go out the same distance & set up
a long straight edge with each end level with the horizon from the perspective of your sight stick , look in the middle & see the sea is higher at the middle, now show this to a flat earther & walk away so they have to argue with the world