Here's something to ponder this week.?ÿ
I was taught to measure on a projection perpendicular to gravity pull at both ends of the measurement in 1974. I always got chewed out for not using a plumb bob. I was told by use of a plumb line and a level bubble I was measuring along the horizontal plane. When I asked what THE horizontal plane was, they told me to shut up and cut brush. Later on, I figured out I was measuring between two projected string lines that get closer together the lower I go and further apart the higher I go (as a rule). I also figured out that THE horizontal plane that is held in such high esteem and is called the GROUND by many is truly only accessible at one three-dimensional point on the earth. Everything else we report on and certify to as being on THE horizontal plane relative to that one point is a lie to one extent or another. My state law even tells me I must survey on THE horizontal plane ( i.e. lie ). We have a lot of interesting discussions about how to lie the best in an effort to certify the world is flat. The least it seems we could do is to codify the plane we should be using in the location we are so the lie we are perpetrating is consistent.?ÿ
how to lie the best
Here's something to ponder this week.?ÿ
I was taught to measure on a projection perpendicular to gravity pull at both ends of the measurement in 1974. I always got chewed out for not using a plumb bob. I was told by use of a plumb line and a level bubble I was measuring along the horizontal plane. When I asked what THE horizontal plane was, they told me to shut up and cut brush. Later on, I figured out I was measuring between two projected string lines that get closer together the lower I go and further apart the higher I go (as a rule). I also figured out that THE horizontal plane that is held in such high esteem and is called the GROUND by many is truly only accessible at one three-dimensional point on the earth. Everything else we report on and certify to as being on THE horizontal plane relative to that one point is a lie to one extent or another. My state law even tells me I must survey on THE horizontal plane ( i.e. lie ). We have a lot of interesting discussions about how to lie the best in an effort to certify the world is flat. The least it seems we could do is to codify the plane we should be using in the location we are so the lie we are perpetrating is consistent.?ÿ
I'm surveying across some mountain ranges in central Nevada, 1979 or so. One measurement in particular stood out. Measured from a high point down into the valley, about a 3 mile distance. Then, measured back up to the high point. Try as I might the two horizontal distances wouldn't mesh. There was about .4' difference. All because of the difference in elevation from the point the measurement was taken from. The higher HD was .4' longer. It's always helpful to see it with real numbers, both were correct.?ÿ
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Don't forget that in many cases we are explicitly told, if not mandated, to both use "the plane" as well as "ground distances". Technically an impossible task from a mathematical standpoint.
@mightymoe This is the exact scenario I have found useful in explaining successfully to attorneys and others why I cannot certify to "true, accurate and complete" or some such nonsense regarding measurements.
All we really we need is some sort of laser beam (Dr Evil) that doesn't bend or disperse, and shoots through rocks so we can measure the actual straight line distance between points.?ÿ Then we can do away with this gravity and elevation hogwash.?ÿI mean really, how hard can this be??ÿ It's like we're working with caveman tools out there.
@bstrand?ÿ
The problem isn't the measurement. It's that there is no single theoretical definition for your measurement to try to match.
In most cases there is a practical value that is good enough, but it would be nice if you knew what you were trying to achieve the best approximation to.
it's all relative....?ÿ ?ÿ How much error do you think you were introducing by pulling on a steel tape and holding a plumb bob steady??ÿ ?ÿ It's >0, for sure.?ÿ ?ÿ?ÿ
I try not to sweat the small stuff.?ÿ ?ÿ
Relax, it was a joke.
And no idea what you're talking about with the theoretical definition stuff.
My state law even tells me I must survey on THE horizontal plane ( i.e. lie ). We have a lot of interesting discussions about how to lie the best in an effort to certify the world is flat
"I do hereby certify that the world is flat, and that all the round earth people are not in compliance with the law..."
Ho boy! I can see a cartoon series somewhere here!
N
Well. Whether you're on the earth's surface or taking a geometry exam, it takes three points to determine a plane.
If you don't believe that, try to make your tripod wobble, level or not.
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no idea what you're talking about with the theoretical definition stuff.
I believe this was Norm's point in the post that started the thread. We all believe there is a mark-to-mark distance between two precisely marked points on a round earth and at different elevations, and it can be measured pretty accurately with GNSS, with distance computed from the XYZ coordinates.
But what is the horizontal ground distance between them? This is undefined a because the horizontal plane at one point misses the other point,.
It isn't just an academic or philosophical matter, as shown by Moe's practical example involving modest distances and significant elevation differences..
@nate-the-surveyor Hey, There are flat earth people all aROUND the world !
