Interactive Horizon Curve Calculator with Diagrams
For this interactive experiment, you can scroll to the Interactive Horizon Calculators and Photos below. If you take your own pictures, all you need is a
camera, two marking sticks, and a tape measure OR a
camera and know the camera’s view angle/field of view.
This interactive experiment will tell you how much curve you should or should not see.
Use the appropriate model below for your needs, and then fill in or select all of the blue fields as needed.
Pay very close attention next time you look out over a large body of water, like one of the great lakes or the ocean. Can you see a slightly curved horizon when you’re only several feet above the water, or does it look perfectly flat?
(
It’s important to understand that if you wear glasses, your lenses can cause a curved distortion of your water horizon. So when looking out at the horizon to see if it is curved, it’s best done without glasses.)
On a Flat Earth we expect the horizon to be perfectly straight with no sense of a curve at all.
On a Spherical/Globe Earth we expect the horizon to have a slight curve, but nearly imperceptible. Noticing a mild curve fitting with a spherical Earth will be easier when looking out over an ocean or a larger lake like one of the great lakes.
Also, if you take photos of your water horizon, you should take pictures with your camera positioned horizontally and then take several pictures
with the horizon at different levels in your view-finder/display. Most camera lenses will increasingly distort the image as the horizon line approaches
top or bottom of the photo frame, so it is important to have the horizon in the middle of the frame.
Show decimal place(s).
When you know your camera’s view-angle
If the center of my camera lens is
above the water,
then my globe-model water horizon is
0.0
away from my camera lens.
And if my camera lens View-Angle is
Degrees when NOT zoomed in,
then my camera is viewing
0.0
of GLOBE-Earth Horizon
and my Horizon is a maximum of
0.0
higher in the center than at the visible ends in my photo.
To put this in perspective, if you tried to display the globe horizon curve using the full width of a 4K TV,
the edge-to-center height difference would only be
of a single pixel.
On a Flat Earth model, I would see
0.0
of FLAT Earth at
away using an angle of
0.0
.
But in the case of Flat Earth, technically, there would be no “horizon” until you reached the edge of the Earth, and there would be no water horizon curvature whatsoever.
When you don’t know your camera view-angle
If the center of my camera lens is
above the water,
then my globe-model water horizon is
0.0
away from my camera lens.
And if my marking posts are
apart
and my Camera lens is
behind the far inside edge of my marking posts,
then my approximate angle of view is
0.0
and my camera is viewing
0.0
of GLOBE-Earth horizon between the posts,
making my Horizon
0.0
higher in the center than where it touches the marking posts.
To put this in perspective, if you tried to display the globe horizon curve using the full width of a 4K TV, the edge to center height difference would only be
of a single pixel.
On a Flat Earth model, between posts I would see
0.0
of FLAT Earth at
away using an angle of
0.0
.
But in the case of Flat Earth, technically, there would be no horizon until you reached the edge of the Earth, and there would be no horizon curvature whatsoever.
Horizon Image Test Tool
Experiment with the photos below.
Controls are below Photo. Because Globe-Earth curvature would be so slight when shown in a photo,
we have created this interactive set of photos for you to experiment with. The pictures below were taken with a low-cost smartphone. The Photos
are unaltered and you can access the high-resolution version by clicking the “High Res” button. You can stretch the photos vertically
and you can rotate them to line up the horizon with the red line. Touch the photo to move the red line or use the red up and down arrows below the photo.
The photos were taken progressively so that you can see how lens distortion can alter a relatively straight line. The top to bottom middle photos (4 and 5) will offer the most
accurate representation of the horizon. Stretching the photo vertically will exaggerate any curve in the photos which can then be compared to the adjustable straight red line.
With a quality camera and lens and making sure your horizon is nearly perfectly halfway in the view finder, if you are handy with photo editing programs, you will be able to stretch a photo
vertically to exaggerate the curve, if a curve exists.