In images taken using a fisheye lens, a straight line will remain straight if it crosses the center of the image. We can use this attribute to determine if a line is straight in reality.
In any fisheye videos taken from a high altitude, there should be plenty of moments where the horizon crosses the center of the image, and we can use those to determine that the horizon line is curved in the real world.
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The quality of a photograph depends on the quality of the equipment. Higher quality equipment tends to give us better results than lower quality ones.
Flat Earthers like to use their Nikon P900/P1000 to take a picture of planets. When they discover their results have far worse quality than the images from NASA, they would conclude NASA must have faked them. In reality, it was due to their equipment are not in the same league as NASA’s, not to mention the skills to operate the equipment.
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The United Arab Emirates astronaut, Hazza Al Mansouri, took pictures of Earth’s features like the Nile and the Persian Gulf during his visit to the ISS. Flat-Earthers claim the pictures are fake because the various objects appear very large compared to the size of the Earth in the picture. The reason is that they do not understand that the ISS is only about 400 km above Earth’s surface, and only a very small amount of the Earth’s surface is visible from the ISS
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If a distant boat is not visible, then it is because of at least one of these reasons:
- Our eyes have limited angular resolution and are unable to resolve the ship at that distance.
- The atmospheric condition is limiting our visibility.
- The curvature of the Earth obscures the ship.
Flat-Earthers like to demonstrate that a previously invisible ship at a distance can be made visible by zooming in. They would use it to disprove Earth’s curvature. They are wrong. There are reasons other than Earth’s curvature that can obscure a distant boat.
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The Nikon P900 and Nikon P1000 are cameras with a very high zoom factor. However, like most other cameras, they have difficulties focusing and exposing bright & small objects against dark backgrounds. They will require special tricks to get proper images of stars and planets.
Some flat-Earthers pointed their Nikon P900 or P1000 to stars and planets, took out of focus images of them and believed the photos are the “real images of stars and planets.” In reality, the photos are simply the results of their failures to operate their cameras.
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The apparent size of the Sun is constant throughout the day, from sunrise to sunset, seen from anywhere on Earth. This fact disproves the flat Earth model and is only consistent with the spherical Earth model.
Flat-Earthers like to show us videos of the Sun that appears shrinking during a sunset. They merely failed to control the exposure. Using a solar filter or the in-camera exposure settings, the size of the Sun will appear constant during a sunset.
The apparent size of the Sun is constant throughout the day, seen from anywhere on Earth, from sunrise to sunset. This fact is only possible if the Sun is very far compared to the distance between any two observers on Earth.
An online digital photo forensics tool like FotoForensics.com uses Error Level Analysis (ELA) to discover the error level differences on a photograph that was saved using a lossy compression algorithm, like JPEG. ELA algorithm enables us to determine if a photo was digitally modified. Similar surfaces and similar edges should appear similar under ELA. If not, it might indicate a digital manipulation.
Flat-Earthers like to use ELA to ‘prove’ a photo has been tampered with. It occurs because they do not understand how ELA works. Most of them appear to assume if the picture is an original, it would show a uniform ELA. Using such a digital forensic ‘skill’, we can actually ‘prove’ all digital photos as fake.
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Observing Earth’s curvature is more difficult when we are too close to Earth’s surface. The highest place within reach of the general public is a commercial passenger flight. Even then, it is still difficult to casually discern the curvature of the Earth from an airplane. With some effort, it is possible to observe the curve of the Earth from a location closer to the surface, as long as we are willing to do some planning and careful observation.
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Stars are not visible in photos of the Moon –including those taken from the lunar surface— because the Moon is sunlit. The exposure needed to take a photograph of the Moon is not that much different from that used to take a photo in daylight on Earth’s surface.
To demonstrate this, we can try taking a picture of the Moon with stars visible, on the conditions: 1. The lunar features, like the craters, are correctly exposed, not overexposed. 2. Taken in a single exposure, not HDR, and not the result of editing. Even if we are using the best camera available today, the stars can’t show up in large enough quantity.
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Camera zoom works by enlarging the center portion of the image, or in other words, by making its field-of-view narrower. Zooming in on the setting sun will not reveal more of the sun, and will only enlarge the size of the sun in the resulting image.
Flat-Earthers are claiming that zooming in on a setting sun will reveal the entire sun, and somehow lift it out of the water. They are wrong. They simply used the incorrect exposure settings. In reality, zooming on the setting sun will never reveal the sun that is already obstructed by Earth’s curvature.
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To an observer, the law of perspective will cause objects moving away in a straight line to:
- appear to approach the vanishing point but never quite reach it,
- never appear to go across the vanishing point,
- appear to shrink in size,
- never appear to be cut in half unless when it is obstructed by another object.
If the Earth were flat, sunsets, sunrises, and other general phenomena where objects are not visible due to Earth’s curvature should not occur. To “fix the problem,” flat-Earthers invented the explanation that the apparent obstruction of a distant object can occur on a flat Earth due to “perspective.” Their “perspective” is simply a baseless ad-hoc explanation that does not resemble how the real-world perspective works.
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JPEG is a method of lossy compression of digital images. When a photograph is saved in the JPEG format, some details imperceptible to our vision are discarded. The JPEG compression reduces the file size at the expense of perfect image reproduction.
Flat-Earthers like to perform “investigations” by adjusting brightness, contrast, levels or curve of an image to find evidence of tampering. If they find irregularities, they will proclaim the picture has been faked. In most cases, these are only JPEG compression artifacts and do not prove anything.
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An analemma is a photograph or diagram showing the position of the Sun in the sky, as seen from a fixed location on Earth at the same mean solar time, as that position varies over the course of a year. The diagram will resemble the figure 8.
The north-south component of the analemma results from the change in the Sun’s declination due to the tilt of Earth’s axis of rotation. The east-west component results from the non-uniform rate of change of the Sun’s right ascension, governed by the combined effects of Earth’s axial tilt and orbital eccentricity.
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Defishing is a process for removing barrel distortions in fisheye images. It takes fisheye images, and convert them to normal, rectilinear images that preserve straight lines. Different fisheye lenses can have a different amount of distortions, and thus, require a different defishing strength.
Some flat-Earthers would deliberately use stronger defishing parameters than necessary for the lens being used. Their intention is not to remove the barrel distortion in the resulting images, but also to introduce pincushion distortions to the images. Pincushion distortion is the reverse of barrel distortion. It would curve a straight line to the other direction from what would be produced by the barrel distortion in fisheye lenses. At a specific position in the scene, it would make the curved horizon to appear flat.
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Visual albedo is the measure of the reflection of solar radiation out of the total solar radiation received by an astronomical body, taking into account only the visible light. The visual albedo of the Earth is 0.37, and the Moon’s is 0.12.
The Moon appears darker if the Earth also appears in the same photograph. Flat Earthers use the fact to “prove” that the picture is fake. They are wrong. The Moon appears darker because it reflects less sunlight than the Earth.
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A solar filter is utilized to reduce the intensity of sunlight and enable a camera to capture the image of the sun with the correct exposure, even under bright daylight. Without a solar filter, sunlight can be too bright to be correctly exposed by a camera.
Some flat-Earthers made their observation of the sun using a camera without a solar filter. As a result, in some of their images, the sun appears much larger due to the fact the camera cannot distinguish the sun and the sun glare around it.
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The amount of horizon curvature that appears in a photograph of the horizon depends on several factors:
- The altitude of the observer.
- The field of view of the camera.
- Lens distortions of the camera.
Some flat-Earthers assume that we should see the same amount of Earth’s curvature everywhere. And when they see the different amount of curvature in the different picture of Earth’s curvature, they wrongly took it as “proof” of some sort of misconduct.
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In photography, bokeh is the way a camera lens renders out-of-focus points of lights. The shape of bokeh depends on the camera lens more than the out-of-focus objects themselves.
Some flat-Earthers do not know how to take correctly focused pictures of distant planets and stars due to their lack of knowledge and the unsuitability of their camera for the purpose. All they are getting are bokeh, which does not tell us much about the intended objects.
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How an object appears in a photograph depends on perspective —the position of the camera relative to the object—, and field of view of the camera. The farther the object, the smaller the object will appear in the resulting image; and conversely, the closer the object, the larger it will appear. The narrower the field of view, the larger the object will appear in the image; and conversely the wider the field of view, the smaller the object will appear.
Flat-Earthers take the varying proportions of the Earth & Moon in different pictures as a glaring inconsistency. They are wrong. The pictures were simply taken from a different perspective and field of view.
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Earth’s curvature is hard to observe from the surface. Even from the altitude of a commercial passenger flight, about 30000-40000 ft, Earth’s curvature is still too small to notice. However, under careful observation, it is not impossible to confirm the curve from the cruising altitude of a jet airliner.
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