When pictures are take from very high altitudes, the horizon has a suble but obvious curvature, technically you could say the earth was still flat but that would mean since this would happen on all points on the earth, it could possibly be shaped like a bunch of potato chips in a cube-like shape (but I very highly doubt it). Both America, the former Soviet Union, Russia, Britain, Japan, China, France, and other countries have sent at least one object into orbit or higher with still or motion cameras as they orbited or observed earth or another celestial body. If you looked at these photos and made a 3D model of the earth or celestial objects of large enough size, you would find (unsurprisingly) that it is a sphere. Photos and video can indeed confirm the shape of an object if all the outer surface area is observed. That's how you could tell from a photo (and your own depth perception) that a sheet of paper if very flat, but a 300+ foot tall moon rocket is indeed not "flat".