[Thork]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

[Rama Set]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

It has been pointed out, many times, that the Nile is virtually flat wrt a datum that follows the curvature of the Earth.

[Gulliver]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

So you can't answer the simple challenge: Find a source that argues your side that says the surface of a flowing body of water must be shaped by the curvature of the earth. This is an inherent part of your outlandish argument. You have claimed it without any support. You have ignored that it's not true at given locations, such as the Falls. You fail.

[Thork]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

So you can't answer the simple challenge: Find a source that argues your side that says the surface of a flowing body of water must be shaped by the curvature of the earth. This is an inherent part of your outlandish argument. You have claimed it without any support. You have ignored that it's not true at given locations, such as the Falls. You fail.

I did. the River Nile is my example. It flows, it should follow the curvature of the earth or jut out into space. I'm at the point where I feel our respective IQs are too far apart for either of us to enjoy a debate so I'm going to let the other FErs entertain you from now on.

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

It has been pointed out, many times, that the Nile is virtually flat wrt a datum that follows the curvature of the Earth.

At least you get the basic premise. Please explain to Gulliver if you have more patience than me.

I did a whole thread on the Nile and the gradient proves the Nile cannot be curving with earth, because a gradient itself is a flat earth concept (triangles). When you apply RET to it, the gradient is less than the curvature of earth and it appears the Nile would flow towards its own middle from both ends. Its a cool thought experiment if nothing else. Play with the numbers. The least you will learn is all gradients are based on a flat earth, and that itself is interesting.

[Gulliver]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

So you can't answer the simple challenge: Find a source that argues your side that says the surface of a flowing body of water must be shaped by the curvature of the earth. This is an inherent part of your outlandish argument. You have claimed it without any support. You have ignored that it's not true at given locations, such as the Falls. You fail.

I did. the River Nile is my example. It flows, it should follow the curvature of the earth or jut out into space. I'm at the point where I feel our respective IQs are too far apart for either of us to enjoy a debate so I'm going to let the other FErs entertain you from now on.

Again, please provide your source. And do stop the personal attacks.

[Thork]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

So you can't answer the simple challenge: Find a source that argues your side that says the surface of a flowing body of water must be shaped by the curvature of the earth. This is an inherent part of your outlandish argument. You have claimed it without any support. You have ignored that it's not true at given locations, such as the Falls. You fail.

I did. the River Nile is my example. It flows, it should follow the curvature of the earth or jut out into space. I'm at the point where I feel our respective IQs are too far apart for either of us to enjoy a debate so I'm going to let the other FErs entertain you from now on.

Again, please provide your source. And do stop the personal attacks.

No, we're done. I don't need to take orders from you.

[Gulliver]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

So you can't answer the simple challenge: Find a source that argues your side that says the surface of a flowing body of water must be shaped by the curvature of the earth. This is an inherent part of your outlandish argument. You have claimed it without any support. You have ignored that it's not true at given locations, such as the Falls. You fail.

I did. the River Nile is my example. It flows, it should follow the curvature of the earth or jut out into space. I'm at the point where I feel our respective IQs are too far apart for either of us to enjoy a debate so I'm going to let the other FErs entertain you from now on.

Again, please provide your source. And do stop the personal attacks.

No, we're done. I don't need to take orders from you.

Then we're left to conclude that you're running away from backing up your outlandish claims, again. I never expected better from you.

[Rama Set]

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

So you can't answer the simple challenge: Find a source that argues your side that says the surface of a flowing body of water must be shaped by the curvature of the earth. This is an inherent part of your outlandish argument. You have claimed it without any support. You have ignored that it's not true at given locations, such as the Falls. You fail.

I did. the River Nile is my example. It flows, it should follow the curvature of the earth or jut out into space. I'm at the point where I feel our respective IQs are too far apart for either of us to enjoy a debate so I'm going to let the other FErs entertain you from now on.

There is nothing in RET (and I challenge you to find a source that argues your side) that says the surface of a flowing body of water must be shaped by the curvature of the earth.

So the River Nile juts out into space? It doesn't follow the curvature of the earth?

I'm done. I gave you the reasons. You being too obtuse to acknowledge them isn't really my problem. I have answered the issue and have not had one counter example of why my assertion is not true.

It has been pointed out, many times, that the Nile is virtually flat wrt a datum that follows the curvature of the Earth.

At least you get the basic premise. Please explain to Gulliver if you have more patience than me.

I did a whole thread on the Nile and the gradient proves the Nile cannot be curving with earth, because a gradient itself is a flat earth concept (triangles). When you apply RET to it, the gradient is less than the curvature of earth and it appears the Nile would flow towards its own middle from both ends. Its a cool thought experiment if nothing else. Play with the numbers. The least you will learn is all gradients are based on a flat earth, and that itself is interesting.

I tend to disagree and I am not sure why you would contend that a gradient can only exist on a flat surface.  If the slope changes with respect to the datum, whether the datum is flat or curved, you can calculate a gradient.  The second definition below appears to be the relevant one:

gra·di·ent
ˈɡrādēənt/
noun
noun: gradient; plural noun: gradients

    1.
    an inclined part of a road or railway; a slope.
    "fail-safe brakes for use on steep gradients"
    synonyms:   slope, incline, hill, rise, ramp, bank; More
    declivity, grade
    "the gradient of Miller's Hill Road is less steep than it was fifty years ago"
        the degree of a slope.
        "the path becomes very rough as the gradient increases"
        synonyms:   steepness, angle, slant, slope, inclination
        "the gradient of the line"
        Mathematics
        the degree of steepness of a graph at any point.
    2.
    Physics
    an increase or decrease in the magnitude of a property (e.g., temperature, pressure, or concentration) observed in passing from one point or moment to another.
        the rate of a gradient change.
        Mathematics
        the vector formed by the operator ∇ acting on a scalar function at a given point in a scalar field.

[Thork]

Gradient is calculated as change in distance over change in height.



You will notice x is always a straight line in gradient calcs. It doesn't curve. Once it becomes a curve, the value for x increases and changes the value of x/y. You can get very odd numbers over long distances with shallow gradients ... like the Nile.

[Rama Set]

Gradient is calculated as change in distance over change in height.



You will notice x is always a straight line in gradient calcs. It doesn't curve. Once it becomes a curve, the value for x increases and changes the value of x/y. You can get very odd numbers over long distances with shallow gradients ... like the Nile.

Yes, but that is how you calculate it on a flat-surface.  If the surface is curved you have to do something more like this:



Where the gradient, obviously would change from point to point, so you take the tangent at that point and calculate the gradient as you mentioned above.

[Pete Svarrior]

Thork, please. You can't simultaneously make threads about how others apparently hurt our cause and then make posts like this. Your ignorance of high school maths terminology is no excuse here.

[Thork]

On a round earth the gradient shouldn't change from point to point because the curve should be constant and also the gradient can be. And gradients are not worked out using tangents.

Thork, please. You can't simultaneously make threads about how others apparently hurt our cause and then make posts like this. Your ignorance of high school maths terminology is no excuse here.

Posts like what? Gradients are flat earth maths. They aren't worked out with tangents. Rise over run. Not with tangents. Find a hill. It'll say something like 1:8.

[Rama Set]

On a round earth the gradient shouldn't change from point to point because the curve should be constant and also the gradient can be. And gradients are not worked out using tangents.

Thork, please. You can't simultaneously make threads about how others apparently hurt our cause and then make posts like this. Your ignorance of high school maths terminology is no excuse here.

Posts like what? Gradients are flat earth maths. They aren't worked out with tangents. Rise over run. Not with tangents. Find a hill. It'll say something like 1:8.

I recommend you have a look at what I posted and reconsider.  It is a pretty open and shut case.

[Thork]

No, you showed me how to calculate the gradient of a curve as someone might do if they wanted to integrate a graph.

I'm saying, when people actually calculate gradients for real world scenarios, they never correct for curvature. Find a single example where they do.
http://www.wyre.gov.uk/info/200134/advice_on_building_work/166/basic_guide_to_calculating_falls_and_gradients_for_drainage
Flat earth all the way.

[Thork]

Something interesting for Pizaaplanet and Rama

Please note: this is for two points on a projection (plane surface) and does not take into account either the Earth's curvature or local or line scale factor.

From the people who produce ordnance survey maps from which gradients are derived using contour lines. And they tell you their maps do not account for earth's curvature.

[Rama Set]

Something interesting for Pizaaplanet and Rama

Please note: this is for two points on a projection (plane surface) and does not take into account either the Earth's curvature or local or line scale factor.

From the people who produce ordnance survey maps from which gradients are derived using contour lines. And they tell you their maps do not account for earth's curvature.

You realize in your own quote it says that this method is used for a projection (plane surface).  Did you bother to ask yourself what it was a projection of?  Obviously you would not need to account for curvature on a 2-dimensional projection, but you also would not count on it for extremely precise results; it gets you in the ballpark though.  That being said, geodetic surveys most definitely do take in to account the curvature of the Earth.

No, you showed me how to calculate the gradient of a curve as someone might do if they wanted to integrate a graph.

I'm saying, when people actually calculate gradients for real world scenarios, they never correct for curvature. Find a single example where they do.
http://www.wyre.gov.uk/info/200134/advice_on_building_work/166/basic_guide_to_calculating_falls_and_gradients_for_drainage
Flat earth all the way.

Do you have an example of this method being used to calculate a distance where curvature would be relevant?  Curvature over a 50m span is negligible and any piping system can likely flex to accomodate it.

[Thork]

Something interesting for Pizaaplanet and Rama

Please note: this is for two points on a projection (plane surface) and does not take into account either the Earth's curvature or local or line scale factor.

From the people who produce ordnance survey maps from which gradients are derived using contour lines. And they tell you their maps do not account for earth's curvature.

You realize in your own quote it says that this method is used for a projection (plane surface).  Did you bother to ask yourself what it was a projection of?  Obviously you would not need to account for curvature on a 2-dimensional projection, but you also would not count on it for extremely precise results; it gets you in the ballpark though.  That being said, geodetic surveys most definitely do take in to account the curvature of the Earth.

Not at all. OS maps do not take into account earth curvature. The very grid system they use for coordinates is exactly that. A grid. It does not warp at all. The lines on it do not match long lat of a sphere. And yet you can piece together multiple maps because it is designed to be done like that.


The Ordnance Survey divides the country into squares of side 100 km. Each square is identified by a pair of letters, as shown in the diagram. Within each square, the easting and northing are indicated decimally, with the number of figures depending on the accuracy required. The easting is always written first.
Note: The map projection used by the Ordnance Survey does not distort angles. Hence the angle on the ground between two lines will be exactly equal to the difference between their geodesic azimuths at the crossing point.

And yet these are used for navigation. there is no distortion in angles and no distortion in distance.

[Rama Set]

Something interesting for Pizaaplanet and Rama

Please note: this is for two points on a projection (plane surface) and does not take into account either the Earth's curvature or local or line scale factor.

From the people who produce ordnance survey maps from which gradients are derived using contour lines. And they tell you their maps do not account for earth's curvature.

You realize in your own quote it says that this method is used for a projection (plane surface).  Did you bother to ask yourself what it was a projection of?  Obviously you would not need to account for curvature on a 2-dimensional projection, but you also would not count on it for extremely precise results; it gets you in the ballpark though.  That being said, geodetic surveys most definitely do take in to account the curvature of the Earth.

Not at all. OS maps do not take into account earth curvature. The very grid system they use for coordinates is exactly that. A grid. It does not warp at all. The lines on it do not match long lat of a sphere. And yet you can piece together multiple maps because it is designed to be done like that.



And yet these are used for navigation. there is no distortion in angles and no distortion in distance.

So can I assume because you have dropped gradients you have conceded the point?

How do you know that map has no distortion?  How much distortion would you expect there to be on the RE view?

[Thork]

No, you changed the subject. I guessed you gave up.

I would expect there to be a distortion as below



There is no grid adjustment at all.

[Rama Set]

No, you changed the subject. I guessed you gave up.

Don't be a Thork.

I would expect there to be a distortion as below



There is no grid adjustment at all.

What?  There is no grid adjustment where?  The map you posted is of how large an area?  How does it compare with this completely contextless diagram above?  Don't you think that the fact that there are scale-factor issues shows that these issues are considered in relevant cases?

Amazingly, a quick search of "scale factor issues map projection" (no quotes in the search) brought up as the first result a document detailing issues with scale factor and the curvature of the Earth.  You know what the second question in the FAQ is, after "Are you an architect, engineer, developer or builder"?  "Why is the distance I measure on the ground not the same as the distance that I measure on off my map?"  Answer: "The most likely cause is that the difference is due to the effect of the projection scale factor."

The document then goes on to reference the diagram you posted, discusses issues with map projections and states that the error between map and reality ranges "between zero and 4cms every 100m".  Sounds like a small error like that could be easily corrected for while navigating by using the sun, a compass, landmarks, anything really.

So here we go again.  You reached a dead-end in showing that gradients only apply to flat surfaces.  You could not show that gradients are not used in real-life.  You failed at showing the maps do not account for curvature as well.

So now that that is done and dusted I suppose this thread can get back on track, whatever that track is.