"Geodetic Surfaces and Datums" by Dave Doyle, NGS, Chief Geodetic Surveyor (Retired). This presentation provides an overview of geodetic surfaces and datums along the history of the datums.
You can’t do much better than Dave Doyle. Thank you to the Florida Surveyors who sponsored this. We are fortunate to have some of his insights and wisdom preserved and available to surveyors worldwide.
This is great!! I’ve recently been given charge of doing some costal surveying for my boss and I want to do a good job. I think anything this guy puts out would be worth watching incredible info love the history he adds ,and the story about Isaac newtons quote… quite ruthless lol love it
Thank you! You answered my question; I needed to fill out a form with latitude, longitude, datum, level of accuracy, and method of measurement. This is very interesting, and presented well. :)
Congratulations for this comprehensive and high quality material, available for free, for everyone. These videos contain several information I've been looking for a while, presented very didactically and, at the same time, with a substantial depth of technical details. Such a great job! Thank you so much!
wow! As a civil engineering majored, land surveying courses were somehow boring and tiresome to me, never realized how important and respectful this profession has been until today. Thank you so much for such an amazing presentation.
thank a lot sir ! such as great explanation for me as a geodesy and geomatics engineering student which is hard to find videos of geodesy especially in indonesian's language .
As an example of some of the issues mentioned herein; I know that modern action cameras like the GoPro HERO11 Black can be toggled between recording the “coarse MSL” value from a 10 by 10 minute grid or WGS84 ellipsoidal height. Personally I’m fascinated by how good the positional metadata gathering of these cameras are and that the reference systems used are fairly well-documented.
I came across this excellent presentation whilst preparing for a course I will shortly be undertaking. I have to confess that I am confused by the illustration from the 'Expeditions of the French Royal Academy of Sciences' at approx. 12 minutes into the presentation. I don't understand why the 1degree arc of latitude at the equator is shorter (rather than longer due to the greater radius) than the 1 degree arc of latitude at the poles. Any help gratefully received. Thanks, Tony
What would be the best way for me to use my auto level to create an horizontal plane over static water and measure the drop from horizontal to show my kids how water curves.
Good afternoon. In Soviet/Russian geodesy, a level surface - "Quasigiod" (proposed by the Soviet scientist Molodensky in 1940) is used to calculate heights. Why is it not used in the West?
That is an excellent question. The decision of which surface to use is academic since their is no significant accuracy distinction between them. My perspective on the subject is not academic but rather from a practical in nature. From the practical day-to-day applications of general surveying, mapping and charting and GIS the more important elements are that the surface (e.g. the datum) is well defined by an authoritative source (the National Geodetic Survey) and that they provide easily accessible datum point realizations (passive and active control points), guidelines for proper observation techniques and easy access to these data and information. All of which is currently available and will be significantly enhanced with the new datums currently planned for release in 2025.
@@daviddoyle8098 According to your logic, it turns out that if your National Agency put into practice the Ptolemaic universe system, to calculate the position of the planets in the solar system (which, by the way, it successfully coped with, although the sun moves around the earth in it), should it be accepted and not objected to ??? People, even autocrats from the Agency, have a habit of making mistakes...
Really? Name 1 thing you learned and UNDERSTOOD from this video that has real-world application. Show me 1geodetic survey that Dave Doyle *CHIEF* Geodetic Surveyor has conducted. *SHOW ME ONE* With readings measurements and verifiable values.
@@daviddoyle8098 *WHERE THE HELL WERE YOU DAVID DOYLE?* Ray Goodwin here. Kansas City, MO. I drove to Borrow County Georgia for this court trial. *THIS IS A MATTER OF/ON PUBLIC RECORD.* Where were you? Where the hell was all the geodetic surveyors? Where were the college professors? Where were the astrophysicists? The NASA engineers? Thompson *BEGGED* for assistance. Offered to share the money. You could have afforded a decent tie and hair cut. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7CvShGryLOo.html
@@daviddoyle8098 Got a request David Doyle. The following link is a time stamped part of a debate I participated in about 3 months ago. I was dog tired, and normally sound a bit sharper and crisp than this. But...I think the discussion is clear enough to understand and follow the dialogue. We are discussing a USGS benchmark set in 1964. I maintain the only way it could have been set was by carrying elevation with a survey that began at the ocean or sea. Mr. McToon claims I'm wrong. And that there are geodetic books and procedures that explain how it was accurately set in 1964 on a globe that checks perfectly today using a GPS receiver. I find Mr. McToon's hollow empty generalized explanation of why I'm wrong arrogant and insufficient. I also find your presentation here in *DIRRECT CONFLICT* with what NASA and other authorities claim. How ancient Greeks got the size and shape of the earth nearly correct using two ancient hand-dug wells. Here, you claim that as recent as the 1700s France and some other country couldn't even agree if earth was shaped like a football, or squished basketball I request your expertise to shore up such inconsistencies. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-IOEFHMyWcjI.html
27:19--again, how was this "wobble" discovered? Was it conceptual? That is, was it conceived to be the case in order to answer a "problem" with observations which didn't make sense because those observations were inserted into a globe model? Since earth's "motion" cannot be detected, how was this "wobble" established? CLUE: it wasn't. Just like Newton's IDEA that the earth had to be oblate, the wobble was invented to address a conundrum, which conundrum wouldn't exist if a fiction wasn't supposed to be reality.
17:09-- again, equipotential is a concept, not a reality. Water flows when the surface is sloped. Water doesn't "flow" in an equipotential world because it CANNOT but only as a concept. We all know why water flows and why the oceans (IN REALITY) cannot have elevation; because if they did, they would....flow. So, while the entire world presents itself as stationary and planar, "SINCE WE KNOW" it's a globe, we have to conceptually create a world where physics operate differently due to the scale of the concept. Rivers flow from higher to lower elevation; why don't the oceans flow? Because they have no elevation; yet if the earth were a globe (just like if you had an exercise ball), the water would run off. We can demonstrate that on the small scale and EVERYONE knows the result EVERY single time. The only way NOT to have that result is to CREATE a concept which cannot be tested or falsified. Anything in science which cannot be tested or falsified isn't science--it's dogma.
Interesting presentation, but it doesn't answer some very basic questions. For example, why is the Geoid used? The answer for this, is that a lot of historical (and current) measurements are taken in reference to astronomical or orbiting objects that move independently of earth, and/or because the measurements taken are depended on "where the gravity is pointing" at the point of measurement. If your measurements are not relevant to space or the local gravitational field (ie like traditional surveying), the Geoid model is completely useless. Height can be defined without it too.
iliasasdf - in this session I cover only the basic definitions of the several geodetic surfaces, the geoid being one of them. If you open up the presentation on vertical datums at about 28:48 you will see that I go into greater detail about the geoid and the integrity of the current US national geoid model.
12:45-no. All you’ve done is demonstrated earth science is based on philosophy and mathematics, not actual measurements because all the earth is is distance and elevation change. All Newton did was deductive logic. But he FIRST had the IDEA that earth had curvature. Then he APPLIES logic to a fictitious concept based on angular physics. Do you see the problem? If you assume the earth to have curvature then anything you discover after that assumption will simply be assuming your consequent. That’s fallacious logic and it is NOT science. I’m still waiting to learn how one gets curvature from data points which simply measure distance and elevation. Still waiting.
12:31-what? That’s it??!! You presented no factual data except to say they found the measurements to prove their assumption. Are you serious? This tells me nothing. I came here to actually learn how the earth was measured to be oblate and all I get is, In South Am they measured a smaller distance than in Paris and Finland. This is the simplicity of surveying: distance and elevation change. That’s it. All geodesy is is back engineering a concept which is fictitious. You get my frustration, right? I watch this hopping for actual data and get a summary word salad which is merely assertion with no evidence but the assertion itself. Absurd.
Less than 2 minutes in, and the speaker has already neglected a glaring contradiction in what he says: He uses an illustration of the globe on the left, citing it as a 'picture taken from space' ('picture taken implies 'photo) then goes on to explain that the real shape is a distorted elipsoid, using the exaggerated illustration on the right. So the glaring contradiction is this. if what he says is true, that the distorted shape is the true shape, then one can only conclude that the photo on the left is NOT a real photo taken from space. Would he not be more thorough to include this fact in his presentation, rather than complacently claiming it to be a picture taken from space? He has said an untruth in the first few seconds of his talk. How can this help his credibility as an educator?
9:55- and here it is… Newton did no measurement but merely extrapolated a known physical phenom-centrifugal acceleration. This isn’t science, but philosophy. You see, when a concept is primary, then MEASUREMENT will be subjected to the concept which, again, is not science. Still waiting for the evidence which was measured FIRST.
22:00-- describes perfectly the indoctrination system. The teacher presents a globe to the class and projects that construct on their minds without any scientific evidence whatsoever. Which 7th grade science teacher ever validated any globe model claim she presents to the class?
Not really, the bible does not actually say that the earth is or isn't a certain shape. Here's my source: www.gotquestions.org/flat-earth-Bible.html Basically, the "200 times" you're referring to are probably idioms.
