Yes, curvature can be measured and modeled as proven by Blackpool Photo

No, what makes both a flat and curved surface initially rise is that they are both mainly flat surfaces for a short distance.

No, what makes both initially "appear to rise" is simple geometry.
for the flat surface it is a=atan(h/d).
For the round surface it is a=atan(h0/d + d/2R)

A curved surface has to have a very very slight curve over it, first at a shorter distance, which makes it nearly like a flat surface, though it cannot be flat, and won’t rise up as high or as far out as a true flat surface will.

Yes, as I have pointed out repeatedly.
The round surface stops and you get a horizon, just like observed in reality.

Curved surfaces don’t appear to rise up

There you go contradicting yourself yet again.
They do rise up.
The question is how much.
If they didn't rise up at all, they would appear as a point.
The fact they don't appear as a point shows

A curved surface has no horizon over it. Only a flat surface has a horizon, a true horizon.

Pure BS, as repeatedly explained.

Go get a ball, or basically any round object, and observe how you can see along the surface until a point at which the surface has curved too much and you can't see the surface.
That is the horizon.
Now get a flat surface, and observe how you can see all the way to the edge.

Countless observations show flat surfaces do NOT have a horizon while round surfaces do.

Can you provide a single example of a flat surface having a horizon? NO!
The only attempt you have is Earth, which is round.

Curved surfaces go downward all the time. Not appear to rise up.

Again, directly contradicting yourself.
You have admitted they do appear to rise.
Saying they don't wont change that.

Horizons form atop a flat surface at the vanishing point.

And the vanishing point is infinitely far away, and NOT the horizon that we observe.

Over a curved surface, two parallel lines would go further away from each other, curving each way out over the curved surface.

Do you know how utterly delusional that is?
Do you have an example?
Or even an explanation of what magic causes that.

Why do you think a curved surface rises?

Simple geometry, as shown repeatedly.

The entire world is flat and forms horizons all over.

Perspective is based on flat surfaces and straight lines that seem to converge over a flat surface which appears to be rising upward in the distance.

If you accept a long surface is entirely flat, you’ll see that it forms a horizon on it.

When we can see an entire ship that is one mile away from us, your curve would go down by 8 inches over the surface, which would make it rise less than when nearer to us.

The bottom part of the ship would be blocked out by that 8 inches of downward curve over the surface at 1 mile out.

The curve would be more and more downward with more distance. This is where it is about mathematical and physical surfaces over curves.

Look at any flat surface which you know is entirely flat.

What would it look like if it was curved over it, out from one end you see it from?

You could curve it way down, and not even see the whole surface at all. No horizon forms over a curved surface. It’s cut off physically by a curve.

A flat surface is easy to prove and measure as flat, by measuring it over each line across and outward.

A flat surface always measures as flat over any and all distances. A curved surface always measured as a curve over any any all distances.

They’re saying that a curve isn’t measured or measured as almost flat over a smaller distance, which is complete bs.

An 8 inch curve over one mile of Earths surface would be immediately seen and measurable with our instruments.

The only reason we don’t measure for any curve, is because no curve ever exists TO measure for it.

Horizons only form on flat surfaces. Look across to the center of a horizon about three miles away. It looks straight across the entire surface, but it’s less than three miles away at each end, but is it really?

No, it is always seen three miles away, wherever you look out at it. Every time you look at it, you see it at the center of another horizon, at another angle of view.

Everywhere you look outward to a horizon, is always the center of that horizon, and is always three miles away from you.

It does not curve around you, it is always three miles away, as your angle of view changes each time.

If you moved in a parallel line to the horizon, or others were seeing it parallel to your line, it would always be seen three miles away.

When you see a horizon as a straight line across, what makes the surface appear to rise upward out from you and form a horizon is due to perspective and vanishing point.

Physically measuring a flat or curved surface is what proves Earths surface is flat.

The entire world is flat and forms horizons all over.

That is entirely circular reasoning.
You are desperate for Earth to be flat so you boldly proclaim it is to dismiss this evidence which clearly shows it is not.
Earth is round, and forms horizons all over just like round objects are known to do.

Do you know what kind of object is known for not forming horizons? Flat ones.

Perspective is based on flat surfaces and straight lines that seem to converge over a flat surface which appears to be rising upward in the distance.

Repeating the same lies will not help you.
Perspective is based upon angles.

If you accept a long surface is entirely flat, you’ll see that it forms a horizon on it.

Now try saying that honestly.
If I accept a round surface is flat, I will accept a flat surface produces a horizon.

When we can see an entire ship that is one mile away from us, your curve would go down by 8 inches over the surface, which would make it rise less than when nearer to us.

Now try that more honestly.
Firstly, what do you even mean by "rise less than when nearer to us"?
Do you mean the angle will be lower?
If so, that is clearly pure BS as shown by simple math.
Again, the math is incredibly simple.
a=atan(h/d).
Or if you want the angle to be negative to show it is downwards, then it is equally:
a=-atan(h/d)=atan(-h/d).

For a flat surface, h is constant so it would be a=atan(-h0/d), and for a sphere it would be approximately a=atan(-h0/d-d/2R).

But we can just look at this ratio:
-h/d.

So lets take an observer 6 ft above the water. That is 72 inches.
Now we look at our 1 mile distance, where you get an extra 8 inches.
That gives you -80 inches/mile.
i.e. to reach this point travelling in a straight line, for every mile you go out you need to drop by 80 inches.

Lets compare that to someone half a mile away, and even be generous and completely ignore the curve up to that point, as if it just dropped after there.
Well that gives us -72/0.5
This is -144 inches per mile, which is LARGER in magnitude than previously, so it wont block the view, it is too far down.

You can even do it properly accounting for the curve.
Doing that you get this:
https://www.desmos.com/calculator/ebzzjqx35q

Notice the key change at 3 miles?
That is where it stops going up and starts going down.
That is what gives the horizon.
That is what blocks the view.

This matches what is observed in reality.
And if you go to that desmos link, you can change the height and see how it affects it.

The bottom part of the ship would be blocked out by that 8 inches of downward curve over the surface at 1 mile out.

Only if your eyes are at eye level.
Why would it magically block it out otherwise?
What part of Earth before it is blocking the view?

Look at any flat surface which you know is entirely flat.

And notice that the only "horizon" is the edge, no matter how close I get.

What would it look like if it was curved over it, out from one end you see it from?

It would still appear to rise up, just to a lesser extent.
And if curved enough it would reach a point where the curve was so great the surface closer to me would block the surface further away.

You could curve it way down, and not even see the whole surface at all. No horizon forms over a curved surface. It’s cut off physically by a curve.

That "cut off physically be a curve" IS the horizon.
The horizon is the border between the part we can see and the part we can't.

Yes, we wont see the whole surface, unlike a flat surface where we can.
And again, comparing to Earth we don't see the whole surface, we just see until the horizon, where the more distant surface is cut off physically by a curve.

Again, this just demonstrates Earth is round.

A flat surface is easy to prove and measure as flat, by measuring it over each line across and outward.

Actually, it is quite difficult. Some would say it is actually impossible.
This is because all measurements have some level of uncertainty.
You can only show it is flat to within that uncertainty.
And within that uncertainty you can always hide a curve. The question is how much.

Again, going back the the approximation, the drop due to curvature is d^2/2R.
So the drop from the centre to the edge is d^2/8R.
So if you can only measure over 1 m of surface, and the radius if 6371 km, then the drop is roughly 20 nm.
So that means you need to be able to accurately measure a 20 nm drop either side over a distance of 1 m.

That chance of being able to do that is ridiculous.
I am yet to hear of any equipment which can.
If instead you use more normal instruments you typically have accuracy at the mm or 10s-100s of microns at best.

You can even test this yourself with a sufficiently large curve.

A curved surface always measured as a curve over any any all distances.

Again, PURE BS!
Any sufficient small portion of a sufficiently large curved surface is indistinguishable from a flat surface.
A flat surface is a limit of a curved surface as the radius approaches infinity.

They’re saying that a curve isn’t measured or measured as almost flat over a smaller distance

Which is completely honest. As shown above.
But to a lying POS like you, you need to pretend it is fiction so you can pretend your inability to measure the curvature over a tiny distance means it doesn't exist.

An 8 inch curve over one mile of Earths surface would be immediately seen and measurable with our instruments.

No, it wouldn't.
Again, it depends on the instrument.

Going back to that geometry, you have 8 inches over a distance of a mile. Do you know what angle that is?
That is 0.007 degrees.
That is NOT something you are going to be able to see without a highly accurate instrument.

And with a highly accurate instrument you can easily measure it.
You just choose not to use them.

Horizons only form on flat surfaces.

Then why do we see horizons on curved surfaces all the time?
Why have we never seen a horizon on a flat surface (excluding the edge).
How come Earth is the only allegedly flat surface which produces a horizon?

Look across to the center of a horizon about three miles away.

The centre of the horizon is where you are.
The horizon is a circle that goes around you.
And like all circles, it is flat.
Just like we expect for a round Earth.
It is an intersection of a flat plane parallel to a hypothetical plane passing level through you, and the surface of Earth.

Do you know what shape the surface of Earth has to be to get that horizon? roughly a sphere.

It does not curve around you

Yet we can clearly follow it all the way around us, without things popping in and out of view.
That certainly sounds like it does curve around us and you are yet again desperate to reject reality.

If you moved in a parallel line to the horizon

It would be impossible, because the horizon curves and the closest to a "parallel line" would be a point.

What you mean is if you looked out to the horizon and moved to the left or right (i.e. perpendicular to your view point), you would be seeing different horizons and things coming in and out of view as you moved.

vanishing point.

Again, the vanishing point is infinitely far away. It is NOT the cause of the horizon.
The cause of the horizon is the same as seen on countless balls, the curve of the surface resulting in it physically blocking the view.
That is what makes sense.
That is what matches reality.

Physically measuring a flat or curved surface is what proves Earths surface is flat.

Except the actual measurements which have the level of accuracy and precision required clearly demonstrate it is curved. And your wilful ignorance of that wont change it.

Likewise, the fact we have a horizon clearly shows it is curved as no one has been able to provide any explanation of what magic would cause a horizon on a flat surface a finite distance away with that distance varying in a non-linear manner with altitude, and with objects beyond the horizon appearing to sink and disappear from the bottom up, and with the horizon appealing lower with altitude.
The only thing close to an explanation is light magically bending (which also has no explanation) to produce the exact results expected for a round Earth.

And your repeatedly lies will not change these facts.
The facts clearly show Earth is round, and all you can do to pretend otherwise is blatantly lie to everyone.

If you wish to pretend a flat surface can produce a horizon, explain how.
In this explanation ensure you provide a formula which links the height of the observer to the distance to the horizon with an explanation of this formula.
Even if you can't explain how, provide this formula.
You previously claimed to have such a formula, but then refused to provide it.
As if you either didn't have one and were just lying, or knew that the formula you did have relies upon a round Earth, and so providing it would show you are a lying POS.

Once you have provided that formula, give us another one showing the angle of dip to the horizon vs altitude.
And no, just lying to everyone by pretending it doesn't go down will not save you. It just shows how dishonest and desperate you are.

The entire world is flat and forms horizons all over.

If so.  Care to address the actual opening post.

So.  The earth is huge, and the amount of curvature is slight to us small humans.

For the claim a laser level should measure curvature?  Not sure how that works on the scale of the earth?  And would be much different than surveying and using line of sight and correcting for the horizontal line? 

The laser does go straight except if bent by atmospheric conditions?  Then you have to somehow measure drop perpendicular to the laser.  But line of sight works the same way in surveying. So the laser level is really a moot point anyway. 

And level surface as defined in surveying follows the sphere of the earth anyway. 



https://gcekbpatna.ac.in/assets/documents/lecturenotes/Surveying_Mod2_Levelling.pdf

So the definition of level surface brings us to the world of surveying.  It was long understood the earth is too big to measure with a flat edge. And the earth can accurately be measured with line of sight (which arguably has the same strengths and problems as “a laser level”), and tweaking with adjusting for refraction.

So surveying ties into the long known dip of the horizon.

Using surveying and the dip of the horizon, it’s long been known that you can calculate the curvature of the earth.



Which can be verified.

Rainy Lake Experiment: Conclusion

http://walter.bislins.ch/bloge/index.asp?page=Rainy+Lake+Experiment%3A+Conclusion

Summary
All data and observations agree with the predictions of the Globe Model, which includes Terrestrial Refraction. The predictions for the Flat Earth Model, however, contradict the observations.
The Rainy Lake Experiment shows even better than the Bedford Level Experiment

 that the earth is a globe, since we also have GPS measurements that are not influenced by Refraction or Perspective, but are of a pure geometric nature. GPS measurements directly provide the radius of the earth.
Only one conclusion remains:
The earth cannot be flat, but is a globe with a mean radius of 6371 km!

Almost to the point of this thread…. Hold on

So I guess this photo a few years ago caused quite the buzz?  Who knew?

A photo by:

Kevin Jackson, of Birkdale, Southport, captured the amazing view of the seaside resort from the Sefton coast.

https://www.lancs.live/news/lancashire-news/stunning-picture-blackpool-thats-set-19719171.amp

https://i2-prod.lancs.live/incoming/article19719194.ece/ALTERNATES/s615/0_blackpooljfif.jpg

As presented by Dave McKeegan in this video.



Now the point of all this.  Blackpool tower looks relatively taller than the background hills because the earth is spherical.



We can model the view of Blackpool Tower relative to the distance hills for a flat earth vs spherical earth.

1. The height of the Blackpool Tower is known.
2. The position of the photographer is known.
3. The radius of the earth is measured and known.
4. The distance to the background hills and their height are known.



If the earth was flat.  The background hills would be taller in the photo than the tower.



A rough model of how the photo should look for the tower relative to the background mountains on a flat earth. 



The evidence is pretty clear. And even supposedly converted this person,Ranty-Flat-Earth, back to spherical earth

https://www.reddit.com/r/pics/comments/odpjrm/this_image_converted_me_from_a_very_prominent/

Go to Blackpool, stand on the beach and then look across to the Isle of Man. It is approx. 67 miles away. You will be able to see - on a clear day - or with the use of binoculars if necessary - the tallest peak on the island which is Snaefell and stands at 2,037 feet.
Now do the maths. Standing at approx. 6 feet above sea level there will be approx. 2,731 feet hidden. However it is possible to see at least half of Snaefell. Probably more owing to refraction. A curved earth would have hidden all of Snaefell.

If you go stand on a beach at sea level and look at the 'horizon' it will appear to move up to meet your line of sight. Just look at any photo taken from a beach - the sea does not curve away from you it stacks up high to the top of the photo. If it were a globe the earth would curve away from you at your very feet - instead it rises up in front of your very eyes. Not possible on a globe.

Go to Blackpool, stand on the beach and then look across to the Isle of Man. It is approx. 67 miles away. You will be able to see - on a clear day - or with the use of binoculars if necessary - the tallest peak on the island which is Snaefell and stands at 2,037 feet.
Now do the maths. Standing at approx. 6 feet above sea level there will be approx. 2,731 feet hidden. However it is possible to see at least half of Snaefell. Probably more owing to refraction. A curved earth would have hidden all of Snaefell.

Now try doing that all properly.
Get an actual location, not just a vague "blackpool".
That allows an actual distance to be known. Because just "blackpool" allows anywhere from 63.2 to 68.4 miles.
Get an accurate elevation.
Are you standing 6 feet above sea level (such as on a pier) with your eyes even higher?
Or are your eyes/the camera at 6 ft?
Or are you standing on some high platform with your eyes then 6 ft above that?
Because taking a quick peek, the likelihood that someone is only 6 ft above is quite slim.

For example, the north pier stands 50 ft above the water.
And then you would be an extra 6 ft or so above that.

Then, accurately calculate, and if you want to note refraction include at least "standard refraction" which is easiest done by scaling R by 7/6.
And importantly, you provide documentation of this, including with pictures to verify it.

Accounting for those issues, you end up with 1707 ft hidden.
So no problem for the globe.

Meanwhile do you know what it is a problem for? A flat Earth. A flat Earth without curvature wouldn't have hidden any.
The best case scenario for your argument is that Earth is larger. Not that it is flat.

If you go stand on a beach at sea level and look at the 'horizon' it will appear to move up to meet your line of sight.

And if you measure it very accurately, you will find it below level.

And if you get higher, it appears lower.

But until you get very high, you need an accurate tool to determine just how low.
But even with a rudimentary tool like a bottle of water, from a sufficiently high mountain you can easily tell the horizon is below level.

And notice what your claim entirely lacks? Any tool to see where level is.

If you think you are that good, go find a blank wall, next to a level surface, and your have a friend draw some horizontal lines on it, and then pick which one is at eye height, then go check.

If it were a globe the earth would curve away from you at your very feet - instead it rises up in front of your very eyes. Not possible on a globe.

Now try to understand the difference between the physical height and the angular position.
Are you trying to suggest the water actually goes up?
Or just that it appears that way?

Because simple math shows the angle of elevation of a point on the surface will rise.

The difference between a flat surface and a round surface is that a flat surface will continue to have that angle rise forever while a round surface will reach a peak and then go back down producing a horizon.

If you wish to so boldly claim something is impossible on a globe, do the math, don't just assert crap.

As a hint, the simple math, ignoring refraction, shows the angle of dip to the horizon is given by arccos(r/(r+h)).
For an observer height of 2 m that gives 0.045 degrees.

If you go stand on a beach at sea level and look at the 'horizon' it will appear to move up to meet your line of sight. Just look at any photo taken from a beach - the sea does not curve away from you it stacks up high to the top of the photo. If it were a globe the earth would curve away from you at your very feet - instead it rises up in front of your very eyes. Not possible on a globe.

The operative word in your post is, "appear".

Appearances can be deceiving and is the case in your example.

You need to spend more time at the beach and let that salty air clear that cluttered garbage filled flat earther mind of yours.

For you to be correct, means billions of people and billions of pieces of information collected about Earth, needs to be wrong.

Do the maths, Simon.

The entire world is flat and forms horizons all over.

Perspective is based on flat surfaces and straight lines that seem to converge over a flat surface which appears to be rising upward in the distance.

If you accept a long surface is entirely flat, you’ll see that it forms a horizon on it.

When we can see an entire ship that is one mile away from us, your curve would go down by 8 inches over the surface, which would make it rise less than when nearer to us.

The bottom part of the ship would be blocked out by that 8 inches of downward curve over the surface at 1 mile out.

The curve would be more and more downward with more distance. This is where it is about mathematical and physical surfaces over curves.

Look at any flat surface which you know is entirely flat.

What would it look like if it was curved over it, out from one end you see it from?

You could curve it way down, and not even see the whole surface at all. No horizon forms over a curved surface. It’s cut off physically by a curve.

A flat surface is easy to prove and measure as flat, by measuring it over each line across and outward.

A flat surface always measures as flat over any and all distances. A curved surface always measured as a curve over any any all distances.

They’re saying that a curve isn’t measured or measured as almost flat over a smaller distance, which is complete bs.

An 8 inch curve over one mile of Earths surface would be immediately seen and measurable with our instruments.

The only reason we don’t measure for any curve, is because no curve ever exists TO measure for it.

Horizons only form on flat surfaces. Look across to the center of a horizon about three miles away. It looks straight across the entire surface, but it’s less than three miles away at each end, but is it really?

No, it is always seen three miles away, wherever you look out at it. Every time you look at it, you see it at the center of another horizon, at another angle of view.

Everywhere you look outward to a horizon, is always the center of that horizon, and is always three miles away from you.

It does not curve around you, it is always three miles away, as your angle of view changes each time.

If you moved in a parallel line to the horizon, or others were seeing it parallel to your line, it would always be seen three miles away.

When you see a horizon as a straight line across, what makes the surface appear to rise upward out from you and form a horizon is due to perspective and vanishing point.

Physically measuring a flat or curved surface is what proves Earths surface is flat.

You continue to prove my argument.

All your flat earth arguments come from your observations of the immediate world around you. We are each surrounded by an immediate world around us.

What you need to try and strain your brain to do, is see that your immediate surroundings are a tiny speck on the surface of a large globe.

Perspective only acts on flat surfaces and straight lines of each side of our viewpoint.

Look at how two parallel lines are always straight lines, because you cannot excuse it with your ‘curvature’ here.

Why are those lines straight and parallel to one another?

There’s no curve at all.

Where do we last see them in the distance? They’re last seen almost as one line converging together, atop the horizon on the surface, right?

We know for certain that both lines are always straight and at the same distance from each other.

How can your curving down horizon work here? The lines are virtually converged together when last seen.

Curved lines that run equal distance from each other don’t appear to keep on converging in the distance, they will curve and often appear to converge to one side and the other side while curving back and forth, or curving off to one side all the way outward.

Curved lines and curved surfaces don’t, cannot, have perspective, the flatter a surface or the straighter a line is, makes persoective act on them, but only to a lesser degree.

Perspective cannot flatten out curved surfaces or straighten out curved lines of equal
distance apart from each other.

Perspective does not ‘beat out a curved surface’ and magically transform it into appearing as a flat surface over a distance!

You cannot draw your curved surface at all.

Because you’d have to draw it curved, while we never see any curves at all over the surface.

Take a look at the guy who went atop the Vegas sphere, from across the surface while he’s in the middle of it.

It’s a smaller model of what would happen on a ball Earth, yet is a big enough ball to know what we’d see on a ball Earth.

Now, imagine stretching it out bigger and bigger.

No matter how much bigger it is, how much less of a curve it has, over a smaller distance, or a longer distance, you’re always atop the ball, and only if it’s seen flatter for a distance will perspective act on it.

But always less than on an actually flat surface.

The flat part is why perspective may act on a curved surface, if flat enough.

When we rise above Earths surface, we know that it cannot rise up over a curved surface hundreds of miles away from us, and even if it could be possible, we’d still have to see the surface lower and lower before we’d ever see it as a complete ball from ‘space’, or a part of a ball from ‘space’!

Of course they knew about this as a huge problem to solve for.

They never show us that part, so nobody has thought about it at all.

Have you seen images of a curving Earth surface taken from planes?

They’d have to look far downward from a plane if it had a curved horizon over it, but it’s shot directly out their windows in a plane, which means they are faking a curve on it.

After we’ve measured the Earth!s surface as flat, with planes, you still deny it is flat.

Level has been measured for centuries, and we know that level is a straight and flat and horizontal line or surface.

It does not, could not, measure for any curved lines or curved surfaces.

The length of our instruments that measure for level, alone, show it wouldn’t even be possible to measure for a curve!

Because curved lines and curved surfaces can’t be measured in short and repeated spans, unless it is able to measure any size of curve on it, to ever know any curve exists at all!

You cannot claim it’s a curved surface but it’s too small a curve to be measured for, you cannot claim a phantom curve exists but cannot be measured at all!

Perspective only acts on flat surfaces and straight lines of each side of our viewpoint.

Stop repeating this pathetic lie.
Perspective is simple geometry.
No matter how much BS you spout, that wont change.

Where do we last see them in the distance?

Getting stopped by the horizon, before they have converged, and clearly showing the horizon is BELOW the vanishing point:

But of course, to a lying POS like you, that doesn't matter.

We know for certain that both lines are always straight and at the same distance from each other.

No, we don't.
We know that they are straight to some level of uncertainty.

Curved lines that run equal distance from each other don’t appear to keep on converging in the distance

Yes, they do.
Because perspective is not magic, and that distance between them will have a smaller angular size with greater distance.

Take a look at the guy who went atop the Vegas sphere, from across the surface while he’s in the middle of it.

Or, why not view it from his perspective?

When we rise above Earths surface, we know that it cannot rise up over a curved surface hundreds of miles away from us, and even if it could be possible, we’d still have to see the surface lower and lower before we’d ever see it as a complete ball from ‘space’, or a part of a ball from ‘space’!

Again, it is not physically rising up. It is simply its angular position. And the math shows it will rise up, until it reaches the point called the horizon.

Just like evidence, including your own, has clearly shown the horizon is BELOW level, just like we expect for a round Earth.

And yes, you see it lower, until you can look down and see all of it in your FOV easily.

Of course they knew about this as a huge problem to solve for.

No, they didn't, because it isn't a problem at all and matches what is observed in reality.

They’d have to look far downward from a plane

Stop with all the vague BS.
DO the math, provide a number.

After we’ve measured the Earth!s surface as flat, with planes, you still deny it is flat.

Now try that again honestly.
After you have repeatedly fled form simple questions and evidence which clearly demonstrate Earth is round, and then proceeded to lie to everyone by falsely claiming planes magically measure the surface as flat, you then continue to lie to everyone by claiming Earth is flat, while the sane and honest people continue to accept it is curved.

And why wouldn't we?
You still flee from these simple questions and continue to repeat the same refuted lies while making no attempt to deal with the refutation.
Continually spouting the same pathetic BS doesn't make your BS true. It just shows how desperate you are.

Level has been measured for centuries

And we know (from a wide variety of evidence) that that is a curve, not a straight line.
You are yet to provide a single example of a measurement capable of measuring the curve which doesn't measure it.

It does not, could not, measure for any curved lines or curved surfaces.

WHY?
You keep asserting this pathetic BS, yet you cannot justify it.

Again, LEVEL, measures for perpendicular to down.

The length of our instruments that measure for level, alone, show it wouldn’t even be possible to measure for a curve!

And if you tried saying that honestly, you would say that you are measuring a straight line with a quite significant margin of error (compared to the curve of Earth) over a tiny distance which is far too small to tell if Earth is flat or round.

Meanwhile, the horizon clearly demonstrates Earth is curved and you keep fleeing from it like the lying coward you are.

You cannot claim it’s a curved surface but it’s too small a curve to be measured for, you cannot claim a phantom curve exists but cannot be measured at all!

Again, try it honestly you lying POS.
The measurements YOU ARE APPEALING TO cannot measure the curve.
That does NOT meant that no measurement can.
Again, a relatively simple measurement that can measure the curve is the angle of dip to the horizon, where simple math relates that angle of dip and your altitude to the radius of Earth.
Likewise, a highly accurate theodolite can also measure the drop due to curvature.

Your wilful ignorance of these measurements does not mean they don't exist.
It just means you are a lying POS.

No, Turbonium.

Try and visualize how tiny we each are, compared to the size of the Earth.

The perspective you talk about, works just fine in our everyday immediate environment. At close range and in close quarters, nobody has to worry about accounting for Earth curvature when applying rules of perspective in art, or technical drawing.

Jackblack may be an impatient, intolerant, asshole on his best days, but he makes good points if you can overlook all the times he calls you a liar or other horrible names, and allow yourself to be receptive to the knowledge he is imparting.

You could potentially learn a lot from Jackblack.

But, if you don't want to learn and grow, what drives you in life?

It always appears to be rising upward over the surface up to a horizon.  And always seen over it as flat, never curved at all.

These are two completely different surfaces, never the same at all.

What do you think levels measure for? The only thing they CAN measure for is a flat and straight and horizontal line or surface.

How could they possibly measure for any sort of curve?

How DO we actually measure for a curved line or curved surface? Not with a level, that’s for sure.

Curves are measured by other instruments, but over a very specific distance, which is called its radius, or arc of curvature.

There’s no way to measure for curved lines or curved surfaces with flat and straight instruments.

If your ball Earth had a curve over one mile in length or distance of 8 inches, we would be able to measure for that 8 inches of a curve, but not with a straight and flat across instrument like levels are!

I’m done with your phantom unknown to exist or measure for ‘curve’, it’s nonsense!

We’ve measured the flat surface of Earth for ages, and every day now, and every day in future, too!

Laser levels use straight light beams, nothing curved at all.

Level is always measured as a straight and flat and horizontal line or surface.

It always appears to be rising upward over the surface up to a horizon. 

Which has been proven false in numerous ways.

Dip of the horizon



Vanishing Point

Flat Earth horizon still wouldn't look flat!

Compressing the photo makes it easier to see.

Or how about a laser test you wanted Turbs. 

From this video…


Learned about this experiment using a laser tangent to the curved earth with a boat as a target on a lake 3 miles out.

Where Are We? Ch. 1 The Circumference of the Earth | Genius by Stephen Hawking

https://indiana.pbslearningmedia.org/resource/hawking_genius_ep06_clip01/where-are-we-ch-1-the-circumference-of-the-earth-genius-by-stephen-hawking/



In this clip from Genius by Stephen Hawking, learn how to calculate the circumference of the Earth. Three volunteers learn by measuring the flatness of the lake that they will be able to calculate the size and shape of the Earth. Using a powerful laser that projects a straight beam of light and a boat, the volunteers shoot the beam across the lake. This experiment shows the curvature of the lake. This was first discovered by the ancient Greek philosopher, mathematician and geometer Eratosthenes. He proved the Earth wasn't flat through observing the sun and the direction it cast shadows. If the Earth was flat, the sun would always shine at the same angle no matter what time of day it was. Using all the data collected from the curvature of the lake the volunteers are able to calculate the circumference of the Earth.

But at the very end of Behind the Curve, Campanella comes up with a similar experiment, this time involving a light instead of a laser. With two holes cut into styrofoam sheets at the same height, Campanella hopes to demonstrate that a light shone through the first hole will appear on a camera behind the second hole, indicating that a light, set at the same height as the holes, travelled straight across the surface of the Flat Earth. But if the light needs to be raised to a different height than the holes, it would indicate a curvature, invalidating the Flat Earth.

Campanella‘s Experiment is just a variation of the below.

We can’t be under a ball, looking up to a higher part of a ball.

There’s only one viewpoint from a ball, another viewpoint is also atop the same ball at another position on it.

Stop using these stupid diagrams, they’re pure garbage.

We can’t be under a ball, looking up to a higher part of a ball.

Dip of the Horizon proves you wrong.

As does the sun would have to visibly turn overhead through the day for a flat earth, but doesn’t.  Especially on the equinox where the sun rises due east and sets due west.

As does the fact the sun doesn’t change apparent size through the day.

As does the fact of a setting sun becoming physically blocked by the earth’s curvature.

As does the fact the North Star doesn’t change in magnitude of brightness and size as one travels south until far enough south of the of the equator the earth’s curvature blocks the North Star from view.

The change in angle to see the North Star.



In relation to the above.  Why an equatorial mount for a telescope works the way it does.

The fact simple dial star atlases for the northern and southern hemisphere are accurate at prediction the night sky. 

Where globe earth results in useful items like equatorial mounts for telescopes and reliable dial star atlases of the night sky that would be meaningless on a FE.

There’s less of an apparent rise up on the surface at that point, it is not a ‘dip’.

It is a slant upward of a lesser degree upward, from a greater upward slant.

Then the lesser slant ends at the horizon line, the vanishing point of perspective over a flat surface.

Curved surfaces don’t appear to keep rising up, when above them.

That’s why we measure the surface as flat all the time in planes, with instruments that prove it is flat.

But why let facts bother your little fairy tale rubbish!

We can’t be under a ball, looking up to a higher part of a ball.

There’s only one viewpoint from a ball, another viewpoint is also atop the same ball at another position on it.

Stop using these stupid diagrams, they’re pure garbage.

And yet you ignore it’s all relative for objects on a sphere.

But why let facts bother your little fairy tale rubbish!

And yet you ignore the very real dip of the horizon.  The horizon vs vanishing point.

Dip of the horizon



Vanishing Point




Where flat earth doesn’t explain why a south celestial pole means something for our earth.

Care to draw out how people in Australia, Africa, and South America can look south and see the constellation Southern Cross?  Where the Southern Cross can be a navigational aid to find south? Find the southern celestial pole. 



And not this..

Quote from: DataOverFlow2022 on March 22, 2024, 01:43:38 PM

Quote from: WISHTOLAUGH on March 22, 2024, 01:18:43 PM

No one uses Sigma Octatntis to navigate to the supposed south pole.

I've ignored nothing, but I am going to start now by ignoring your stupid bullshit.

??

You keep trying to change the subject with basically lying how navigation in the southern hemisphere works with a sextant.  It’s not based off the celestial South Pole for the southern hemisphere where Polaris isn’t visible because of the earth’s curvature? 

How to find the celestial South Pole makes sense on a globe / sphere.






The celestial South Pole is meaningless on a flat earth

It always appears to be rising upward over the surface up to a horizon.  And always seen over it as flat, never curved at all.

No, it is not seen as flat.
That is your pathetic assertion.
The easy way to tell it is NOT seen as flat, IS THE HORIZON!
Flat surfaces don't have them. Curved surfaces do. And that is basically how you see it as flat or curved.
And that is the very thing you have been continually fleeing from.
You have no explanation at all for what causes the horizon on a flat surface.
You have no explanation at all for why it appears BELOW eye level, and instead need to repeatedly lie to deny reality.


If you wish to disagree, why don't you try explaining just what magical observation you are making that allows you to see it "as flat".
Don't just pathetically assert you see it as flat. Clearly explain the observation and clearly explain how that would differ for a round object.

What do you think levels measure for?

Perpendicular to down, as already established.

If your ball Earth had a curve over one mile in length or distance of 8 inches, we would be able to measure for that 8 inches of a curve

And you can, using a theodolite.
You need an accurate enough instrument to measure it.
But you have no interest in doing so.
Instead you appeal to instruments which can't measure to pretend it can't be measured.

I’m done with your phantom unknown to exist or measure for ‘curve’, it’s nonsense!

You mean you're done with your strawman?
As opposed to the very real curvature which has been demonstrated to exist countless times in many different ways.
The most relevant of which for this topic is the horizon, something you have been continually fleeing from.

We’ve measured the flat surface of Earth for ages

Yet you cannot provide a single measurement which shows it is flat rather than curved.
Instead you just keep appealing to your wilful ignorance.

We can’t be under a ball, looking up to a higher part of a ball.

And all that does is rotate the picture.
If you are that pathetic and desperate you have no argument.
You would have to be a complete imbecile to understand that.

There’s less of an apparent rise up on the surface at that point, it is not a ‘dip’.

No, that is a dip.
It is a downwards angle, an angle from straight out level downwards.

Then the lesser slant ends at the horizon line, the vanishing point of perspective over a flat surface.

No, it doesn't.
It ends BELOW it, and far more importantly, MUCH CLOSER!

Curved surfaces don’t appear to keep rising up, when above them.

No, they reach a horizon at which point they would appear to "go down", if you could see it.
i.e. exactly what is observed in reality.
Conversely, flat surfaces would continue to appear to rise up, never stopping.

That's why the horizon clearly shows Earth is round.

That’s why we measure the surface as flat all the time in planes, with instruments that prove it is flat.

No, this just proves you are a pathetic lying POS with no concern for the truth at all.
You have had that BS refuted countless times, with you completely incapable of showing any fault at all in the reasoning used to show it is pure BS; so much so that you just entirely ignore it and repeat the same pathetic BS again and again.
All you are are proving is how pathetic and desperate you are.

If you had a shred of integrity you would have admitted that planes do not measure Earth as flat, and never say it again.
But you don't.
You don't care about the truth at all.
You just care about spouting whatever BS you can come up with to pretend Earth is flat.

Meanwhile, you can't even answer trivial quesitons which show it isn't.

Again:
WHAT MAGIC CAUSES THE HORIZON?
What determines the distance?
Why does this vary with altitude?
What is the formula relating distance to altitude?
Why is there an angle of dip?

Can you honestly answer any of these?
NO!

Illusions can be thought of as being ‘magic’, but they look real to us, even if we know they’re not real.

Horizons are created by the same magic which makes the surface appear to rise upward in the distance. They are the final part of the whole illusion of perspective over long flat surfaces.

They are not physically there, they don’t actually exist at all.

They’re created by perspective over long flat surfaces, in classic horizons on the flat surfaces.

Look at a table, which is flat. How would a curve over the table look? It would look different, and not rise up as high as the flat table does. Even just a little less than a flat table would rise up, or appear to rise.

Which means, a curve goes against the illusion of it rising upward, only a perfectly flat surface appears to rise highest upward over it.

Perspective is a function of flat surfaces and straight parallel lines seen over a distance.

A curved surface is the opposite of what perspective creates.

It’s very easily shown but you refuse to accept a long flat surface could exist at all.

Seeing an entire ship going out one mile, is not curving 8 inches down and blocking out 8 inches of the ship.

The entire surface one mile out is flat, and appears to be rising upward.

Same as we see from 2 miles out, but even more curve not there at all. Still flat over it, still appearing to rise upward.

Only when the ship is near three miles out does the surface appear to rise lesser, and the very bottom of the ship not be seen anymore.

Yet the whole surface is still seen as flat, only at lesser of an angle than it was before then.

Perspective cannot, will not, does not, flatten out and transform any curved surfaces to become perfectly flat, to ‘win out’ over a curved surface!

The actual surface is not changed into another surface, by perspective.

As much as you want perspective to flatten a curved surface that’s actually flat, seen as flat, simply because it IS flat.

No curve exists, but within your dreams and fairy tales

Illusions can be thought of as being ‘magic’, but they look real to us, even if we know they’re not real.

Again.

Dip of the horizon alone kills your delusion.




Do you understand these are photos capturing the dip of the horizon, something you can measure and capture for yourself. 

Illusions can be thought of as being ‘magic’,

Which has nothing to do with the opening post of this thread and the Blackpool Tower and why the mountains behind it appear to be lower than the height of the tower, where on a flat earth they would appear taller than the tower. 

All you can do Turbs is detail threads like a typical flat earther. 

A city 50 miles away is seen, a flat lake between you and the city. The very bottom isn’t seen due to perspective. There’s no curvature that would make half the buildings cut out of sight down your curved ball surface.

It’s not refraction, it is the real buildings we are seeing 50 miles away.

That proves Earth is flat, not a skewed shot that anyone can make how they want it to look.

You rely on skewed images that are not valid at all

We have never built or designed bridges or railroads or skyscrapers with any accounting for a curvature, and if there were any curvature, we’d have to account for it all the time building these structures.

Surveyors don’t account for any curvature, not because it’s ‘small enough a curve to ignore it’, but because there IS no curvature TO account for at all.

Surveying land takes everything into account, it has to. It assumes the surface is always flat, and makes whatever is not flat, into flat land.

Reality shows there’s no bs curvature at all, practise and design and surveys and builds prove its flat, and always has proved its flat, and always will prove its flat. No more bs made up curve story, it’s dead and buried as a grotesque fairy tale story.

We have never built or designed

You’re changing the subject with another lie.

Do you understand the dip of the horizon can be documented and measured.

Dip of the horizon



Vanishing Point




Do you know the curvature of the earth is proven through experiments.




  Turbs stop running away and derailing this thread from its topic. 

The Blackpool Tower and why the mountains behind it appear to be lower than the height of the tower, where on a flat earth they would appear taller than the tower.

All you can do Turbs is derail threads like a typical flat earther.

A city 50 miles away is seen, a flat lake between you and the city.

Covered extensively.

And this is Chicago at 40 miles away. 


New Buffalo, MI (40 miles from skyline)



https://yumyummatt.wordpress.com/2014/06/13/chicago-as-seen-from-around-south-lake-michigan/

Holly cow Turbs.  You can only see the very top of Chicago’s tallest buildings at 40 miles as predicted by earths curvature. What, three or four at most? 

Shouldn’t you see all the buildings on a flat earth? 


Where flat earthers hijack and steal the photographer Nowicki’s work.  Ignore his methodology and his own words.

https://www.abc57.com/news/skyline-skepticism-the-lake-michigan-mirage

“I do go out and take a lot of photos of Chicago along the lake. I go to different locations on different nights. I like to compare the photos as to what's changed. Are the buildings wider, taller, shorter are there more of them? Less of them? It's always different, it's so unpredictable, I want to catch as many different views of it as I can," Nowicki said.

To those that doubt affects of refraction. The full Chicago skyline should be visible all the time if it weren't the case, barring clouds, rain or fog. However that’s not the case, it is always changing. I encourage anyone to go look for themselves.

Where you don’t understand, or ignore the pictures you are referring to are from the tops of dunes on the Indiana side of Lake Michigan 150 to 250 feet above lake level.  Where Chicago isn’t normally visible on clear days, but under specific weather conditions of refraction and mirage.

The below is a flash comparison of Joshua Nowick’s photos.  A person that you are basing your claims off of.  Which is.  You think buildings literally grow in length with no change in width.  Or you posting claims on photos you think are digitally manipulated and faked? 




The photos show the photos of Chicago across the lake are due to mirage.  Or the buildings wouldn’t be changing height, especially with no change in width.

Illusions

Have absolutely nothing to do with this.
Again, perspective is simple geometry.
The horizon forming on a RE is likewise simple geometry.
If you wish to invoke magic or illusions you will need far more than your pathetic assertions.

Horizons are created by the same magic which makes the surface appear to rise upward in the distance.

That is not magic.
That is simple geometry.
A formula you have been provided with many times.
Again, the angle of dip, a, can be calculated as:
a = atan(h/d).
For a perfectly flat surface, that will give you a=atan(h0/d).
If you plot this you see that the angle decreases, continually, giving you the "appearance" of a rising surface.
But if you describe it honestly, you aren't seeing anything rise. Instead the angle between straight out level, and a point on the ground some distance away decreases with increasing distance.

But for a round surface, h is not constant.
Instead, as a first approximation, you have a=atan(h0/d + d/2r).

This also initially has the angle decrease. But eventually it reaches a point where it begins to increase again.
That point is the horizon.
That is real physical point, the edge of a sphere which you cannot see past.

NONE OF THIS is an illusion.
But again, you being the lying POS you are need to pretend it is so you can just assert that whatever nonsense you need magically happens for no reason at all.

They’re created by perspective over long flat surfaces, in classic horizons on the flat surfaces.

No, they aren't.
They are created by simple geometry (which might be called perspective) over ROUND surfaces, as seen on countless round surface and NEVER seen on a flat surface.

Look at a table, which is flat.

Where the only horizon we see is the edge, where it curves down.

Compare that to a ball, where no matter what angle you view it from, you get a horizon.

How would a curve over the table look?

Depends how significant it is.
If it has a large enough radius of curvature, you wont be able to tell the difference.
If it curves enough, and you are low enough, you will get a horizon forming, a point beyond which the surface hides the rest.

It’s very easily shown

Then why are you completely incapable of doing so.

you refuse to accept a long flat surface could exist at all.

I do accept it can exist.
I'm just not going to allow you to use a long level surface, which curve following the curve of Earth, to pretend it is a flat surface to pretend a flat surface produces horizons.
Because that is entirely circular reasoning to try to defeat a simple argument which conclusively shows Earth is round.

Again, if you want to assert a flat surface will magically produce a horizon, try explaining how.

Seeing an entire ship going out one mile, is not curving 8 inches down and blocking out 8 inches of the ship.

It is if your eyes are at sea level.
Notice how even you admit that the curved table would still rise, just to a lesser extent.
The same happens here.

You can even test it with a curved table, and see how if you are high enough, the entire object sitting on the surface is still visible.

If you want to hide it from view it needs to be beyond the horizon.
That is because once you go past the horizon, the angular position of the object is lower than part of the surface in front of the object, so it blocks the view.
Before the horizon that isn't the case, so nothing gets blocked from view.

Again, it is really simple. So simple a child could understand it. But here you are still playing dumb.

The entire surface one mile out is flat

No, it isn't. And you just lying to everyone wont change that.

but even more curve not there at all

Based on what?
Just what observation or measurement are you making to confirm that?

Only when the ship is near three miles out does the surface appear to rise lesser, and the very bottom of the ship not be seen anymore.

Just like we expect for a round Earth, and NOTHIGN like we expect for a flat surface.
Once again, this observations refutes a flat Earth and confirms a round Earth.

Yet the whole surface is still seen as flat

No, it isn't.
We don't see the whole surface, just the bit to the horizon.
And you are yet to explain just what magical observation you are making which allows you to see it as flat.
Do you mean you are just so pathetic and desperate for it to be flat that you "see it as flat" regardless of what it is?

As much as you want perspective to flatten a curved surface

No, we don't.
That is just your pathetic strawman.

No curve exists

Except the curve which clearly does as clearly shown by the horizon.
Something you STILL refuse to explain.

A city 50 miles away is seen, a flat lake between you and the city. The very bottom isn’t seen due to perspective.

Perspective has no ability to hide the bottom.
If it did, you would explain how.
But you can't, so you just repeat this pathetic lie.
The very bottom is not seen due to curvature.

There’s no curvature that would make half the buildings cut out of sight down your curved ball surface.

Except the curvature that has already been explained to you, Curvature you could easily test yourself with any large ball and an object you can stick on it.
Again:


This shows a building (or any object really) as that black line off in the distance.
It then shows the limit of vision for 3 hypothetical observers at different altitudes.
The blue observer is the lowest. Their horizon is the closest, and has the entire building blocked from view.
The purple is up next, being at an intermediate height, with a portion of the building hidden.
And the highest observer sees the entire building.

So yes, curvature most certainly can hide half the building.
Do you know what can't?
Perspective.
That is because perspective simply makes things appear smaller.
If the top of the building is resolvable the bottom should be as well.

The only time perspective would hide part of a building is when the building is much thinner at the top, so it could be to thin to resolve the top.

That proves Earth is flat

No, it doesn't.
The fact the bottoms of the buildings are missing proves Earth is not flat.

We have never built or designed bridges or railroads or skyscrapers

You could have just left it there, as you haven't done any of it and have no idea what they do.

As another thread shows, they clealry do account for curvature when it matters. You lying about that wont change it.

Reality shows there’s no bs curvature at all, practise and design and surveys and builds prove its flat, and always has proved its flat, and always will prove its flat. No more bs made up curve story, it’s dead and buried as a grotesque fairy tale story.

Wrong again.
Reality clearly demonstrates time and time again that Earth is round.
With mountains of evidence proving it is round and not a shred of evidence demonstrating it isn't.
You have NOTHING to show it is flat. Instead you just continually assert it is.

Meanwhile, the horizon is clear evidence that it is round.
Again, in order to refute this you need to EXPLAIN how a flat surface has a horizon.
This is not just a pathetic assertion that it does.
You need to explain the mechanism that produces it.
In doing so, you should be able to produce a formula relating the altitude of the observer to the distance to the horizon.
And if that is just based upon straight lines and flat surfaces, it should be linear, i.e. doubling the altitude should double the distance to the horizon.
Unfortunately for you, reality shows that is not the case.

And once you have done that, you need to explain the angle of dip of the horizon, something that yet again clearly shows Earth is round.

Then you need to explain how this horizon magically blocks objects from view and makes them appear to sink.

Until you do that, the horizon remains clear proof that Earth is round, and no amount of pathetic, desperate lies from you will change that.