Sandor Szekely

Dear all! I have made the presentation to the Hungarian Geological and Geodezical Institute, and we have aggreed to make a cooperation on the upcoming Balaton lake and over land laser curvature measurements! We are now applying for director approval and then setup the first measurement on the lake. https://www.mfgi.hu/en/node/456 We will show our plan for the experiment after it has been properly designed and animated so we can discuss the hints and tipps before the measurement is done. 1) This should start with a standard aims and objectives statement. The aim of the experiment is to measure the curvature of water surface at the lake Balaton. 2) Then provide an estimate of the expected range of measurement values and accuracies required so suitable equipment and experimental methods can be devised. We are aiming to take measurements from 10km up to 77kms on the lake surface. Detailed description will include all measurement calculations and experimental methods. 3) Offer a system of control or reference points, established to a higher standard than the survey itself and preferably established by a different method, independent of the survey measurement technique. We are aiming to fixed objects on shore in different heights as planned. 4) Provide a proper method statement for the survey itself. This is not yet ready. I'd like to add one comment to the lake: the Balaton does not have an all time functional outflow, because it is blocked and opened only once in a few years.

I don't have a degree in math, but I get along well I worked as a cameraman long time ago and became an inventor 2 decades ago. I get along with technical English, but I am thankfull if you correct me! I use dictionary to search terms that I am not familiar with, but I may use them incorrecty. "the combined addition for curvature and refraction" thanks this makes it perfectly clearly understandable I'd like to calculate the amount of curvature that we are looking for, so we know what precision we have to do in our measurements. I see that it would be very hard to determine the difference of few centimeters on these distances, but looking for meters of difference should be very well measurable.

I have a confusion here: your chart says 4.9kms is 1.68 meter the curvature of earth in the 4.9 kms distance is 1.88 meter. so is the refraction here 0.2 meter or 1.68? "I do not intend protracted discussion about refraction here since it small in your case and largely irrelevant." in the case of 0.2 meter, maybe but I still don't see how it can be standardised as it deends on the local condition change. "One interesting point is that the variation of refraction with the frequency of the EDM leads to a phenomenon called dispersion which allows accurate measurement of the refraction over the whole observed line of sight with polychromatic light. Monochromatic sources do not allow this but special two colour laser systems such as 'Georan' are available to exploit this." Please tell me more abut this, I think this is exactly what I figured out with the dual colour laser too. So as I understand there are eqiupment like this? "Your objective is to measure the actual shape in space of the surface of the lake, is it not? You should be aware that the surface of water bodies on Earth is rarely level, flat, equipotential etc." My objective is to find out the shape of the water surface, if it is flat or curved. I think there is a huge difference in the outcome of the 2 models already at a shorter distance of 10kms, and a huge difference on the 77kms of the lake. This should be significant enough to exclude one of the models. I am not aiming to make the most precise measurement just to the accuracy that we can determine the shape of the surface: is it flat or curved? Is it possible to have 465 meters drop of curvature on the lake Balaton? Yeah maybe some Bull's blood would be good for me but I never drink alcohol

We will use a board big enough to capture the whole beam in the upcoming experiment. Way more easy than to get the same size of any detector. temperature is such that de My question is : how can anyone estimate, or use a standard value for terresterial refraction? Refraction is caused by change in ambient conditions like pressure, temperature, density or humidity (...) In the case of atmospheric refraction, light coming from thousands of miles from vacuum through more dense, humid, warmer and pressured air it has a well definable "standard" value. Change is more-less the same. But in the case of terresterial refraction like in our experiment the laser beam is going within a short height difference above water, conditions are nearly the same all the way. In this case the refraction can not be pre-determined as it depends on local changes. Refraction is also not a curve but a bend at certain points (where conditions change) and connected with straight path of light. So in my opinion terresterial refraction can only be measured, but not calculated with a standard formula. What is your opinion on the best way to measure it? (mine is to use different colours, but we did not have the collimator for the 2nd)

Hello Studiot I've been sick for the last days therefore had a lot of reading on the refraction subject. Please note here at end of page 26 "Assuming 17 levelling setups along a levelling line of 1 km, the total systematic devia¬ tion caused by refraction is 0.75 mm/km. For comparison: the standard deviation of height differences obtained by precise levelling using digital levels is about 0.3 to 0.4 mm/km (double run levelling) as reported, e.g., in [iNGENSAND. 1995J. There¬ fore, the refraction influences should be taken into consideration." "In order to obtain a hypothesis-free reduction of refraction influences, it is necessary to determine the refraction influences integrally along the propagation path" Summary of page 29 http://e-collection.library.ethz.ch/eserv/eth:23778/eth-23778-02.pdf Please explain in your referenced table what is the 2nd column and what it is it measured in? (meter?) In general I think terresterial refraction can not be calculated with a formula, especially not correspondent to the earth curvature. In other words: refraction has nothing to do with curvature. In my opinion terresterial refraction can be measured but not calculated, as terresterial refraction is due to LOCAL changes. Unlike atmospheric refraction where the ambient data can be estimated and the change of conditions are more alike. Refraction is bending the light due to CHANGE of the medium. I see no constant or presumable change on horizontal distance measurement. It is not like sunshine coming from near vacuum and entering into more dense, humidand warmer atmosphere - where we can estimate the effects roughly. Terresterial refraction is caused by LOCAL changes and temperature/ pressure differences, like a hot spot. That is a bending point of the laser, but NOT a continous curve at all. At the moment I see that refraction may be measured with different color of laser beams, and it can not be estimated nor calculated. so we have to look for theautoconvective laps rate condition: In my opinion the laser beam is going in a straight line between the bending points, therefore that is not a curve. The suggested laser beam refraction is 1/7th of the curvature in this example on this page (or the horizon distance is +7%) http://mathscinotes.com/2013/08/distance-to-the-horizon-assuming-refraction/ here some interesting data on convective stability http://meteorologytraining.tpub.com/14312/css/14312_53.htm Kalynos, I am a cameraman... a ccd is a device that has lenses and other stuff too.. that is called the camera. All sensors have optics.

Opps, whitch one I forgot to answer? I've not watched the video. I did fear this might be the case. You can get "bright" spots off of thr beam path, and you'll be killed by any beam divergence or laser wobble. I don't really think this experiment is within the reach of a hobbyist. Although it looks simple as soon as you start actually thinking about it there are so many subtleties that will make your results meaningless. so I should answer: no I can't get "bright spots" off the beam path. "killed by" what is that term? "Although it looks simple as soon as you start actually thinking about it there are so many subtleties that will make your results meaningless." what does this sentence mean? you say surface can't be measured with laser? well... this is your opinion and I have mine That's a terrible way to measure. You could do something similar with a camera sensor but where you measure the intensity from each pixel. But you'd need a large area CMOS or ccd and some clever way of removing ambient light. IS that a terrible way? LOL have you seen Stephen Hawking Genious video (attached here before)? my favourite part: But you'd need a large area CMOS or ccd a digital camera IS MADE OF A CCD please point me to your important suggestion, it looks like I did not find it

I think your calculation is far off from reality. PLease explain that excel with words too: you suggest, that at c37 6000meters: beam diameter is 11.75 meter? you say, that the calculated bottom of the beam is at -2.97 (meter?) How is that possible? then it should be visible on the board and it shall hit the water NONE of that is recorded... Please clear your calculations. your calculation is way wrong starting with a false assumption on the leveling. C1 - C4 is NOT measurement points. How do you come to this divergence calculation anyway? do you realize that the beam was reflected from the metal frame and therefore it spreads the beam? "This beam is spreading at an increasing rate of divergence rather than some fixed divergence angle. " how did you come to that conclusion? I think your calculation on beam divergence is way wrong

Michael you are wrong. Read through the lidar experiment again, Balaton lake DOES NOT flow like a river. It is a "trully level surface". " It has a level +150.55 at inflow (left on the picture) and 149.65 at outflow, a difference of 90cm from level." Very wrong and missleading.. NO the highest point of the lake is NOT at the inflow, and the lowest point is NOT at the outflow. (just to tell you for a less "misspresentation of the lidar experiment" I have been banned from an other forum... amm... just to inform You all: the RIVER Danube has a 26 cms drop over the COMPLETE route in Hungary. You say seriously that the lake has 3x more on a distance of 1/10? lol As a moderator I think you should be concerned to avoid discussions like this from the forum: "I suppose so it's just there to catch attention to YouTube video, to earn money on advertisements from Google. Scientists seeking for the truth don't behave like that. " IS this personal or has to do with the experiment evaluation?!

Hello Mordred We did think about using dual colour laser (and used it on the pre-test) to calculate reftraction by the difference of the blue / green beam. The cons are not a problem, indeed I'd like to add more types of equipments to improve the measurement accuracy. Actually we have only one problem with this: we have only 1 collimator that is on the green laser. We might be able to get an other one too. Could you please explain this in greater details? "The above may work better if the two lasers were aimed to a common point. Forming two sides of our triangle, this can help in leveling and distance from emitter calcs. (KEY NOTE do not mount the two lasers onto the same mount backboard. We don't want to add material expansion/contraction problems)" no, wedo not have laser scanner (mirrors) in this laser unit. As I pointed out, the horizontal vibrating effect was due to the laser beam hitting the water surface at the 3rd measurement (reflexion) I think there is a confusion on the meaning of "level". Here are some definitions, copy Nr1 here: "Level \Lev"el\ (l[e^]v"[e^]l), a. 1. Even; flat; having no part higher than another; having, or conforming to, the curvature which belongs to the undisturbed liquid parts of the earth's surface; as, a level field; level ground; the level surface of a pond or lake. [1913 Webster]" http://onlinedictionary.datasegment.com/word/level+surface Okay so you have NOT watched the video? then what are we arguing about? "not within the reach of hobbist"... come on.. please be more serious in commenting the experiment! Sensei, I did not answer this post because I found it unrelevant and unpolite. you asked for it so I'll answer. "And honestly must say, you spend the more time flying helicopter and playing volleyball than thinking and preparing for gathering data during the experiment. what is this very first sentence? I'm usually not replying to intriques... helicopter was supposed to enter the measurement, but we had to cancel that due to the storm. On the 3rd (THIRD) day we made some test flights for the upcoming measurement over land. We did not play volleyball... that is a videoclip from someone else... OMG... this is like facebook... I am here for scientific debate - I'll leave all coments like this unanswered in the future. About the size and position of the board : I answered that already, so I will not repeat my self - look back in the comments here. I am sorry, if you have not seen the GoPro mounted camera on the board... 4k is not need Captain WAS doing just fine job. I see you have no idea about a real measurement... I see you still do not understand that WE DID NOT USE the tape measure... it was at the leveling process and NOT the measurements. I am bored to answer questions like this... NEVER EVER AGAIN COMMENT ON MY BELIEFS! AND NEVER EVER mention like "It will obviously put you in "crackpot zone"" I give respect to people here and I DO WNAT THE SAME. If it starts to be like the other forum I will leave you too... "I suppose so it's just there to catch attention to YouTube video, to earn money on advertisements from Google. Scientists seeking for the truth don't behave like that. " REPEAT AGAIN: NEVER EVER TALK TO ME LIKE THAT! I AM NOT YOUR FRIEN, NOR A PARTNER. I AM GOING TO IGNORE YOU FROM NOW.

I will share - and cooperate - with scienceforum on the experiment setup and methodology as I think this is in the interest of my university partner as well. We (Zack, Steve, me) would like to have an open source measurement and a cooperation in the evaluation too - that is the reason I have the post here on scienceforum (ONLY) and let me share with you a PBS production : Genius with Stephen Hawking. The very first part of the film starts with a laser measurement and a boat. There is absolutely no scientific approach in this film - just a mainstream TV production - as they have not given any parameters or real measurements. You might like to check this film to understand better our motives to make a correct scientific approach to the question of curvature on water surface. https://www.youtube.com/watch?v=oNZOh4SUWUc

right 1. on the methodology I think it would be good to combine different techniques. I noted suggestion on various leveling equippments already, please advise how these different techniques can be used simultainosly to improve accuracy and exclude systematic errors from the measurement. Like how could a theodolite (possibly more in different positions) help to measure the laser beam height (maybe divergence too)? In this case of multiple theodolite laser height measurement we could make the measurements at the very same time (not like the boat 2.5 hours). Please share suggestion on this or any other possible method. What is your opinion on measureing on the frozen lake surface? (theodolites can be placed on the surface. refraction at night time or day time? is any posiible duct?) 2. human error will be best reduced with the help from professional geodezysts 3. instrument error may be reduced using multiple techniques?

Thank You MrMarker very well summarized. "As I see it, the experiment was a POC and what Sandor is trying to do here, coming to this forum, is getting ideas and suggestions on how to get it right the next time." Exactly I am here for this reason, and I am very pleased with the REAL scientific approach from most of You here! I am reading through the comments (taking the notes ) and as well organizing the real scientific team and the new measurement. Excuse me that I comment less now - I am listening carefully to the comments and I "try to catch up" with the terms and the explanations. (my profession is a cameraman) Klaynos: "I've not watched the video. I did fear this might be the case. You can get "bright" spots off of thr beam path, and you'll be killed by any beam divergence or laser wobble. I don't really think this experiment is within the reach of a hobbyist. Although it looks simple as soon as you start actually thinking about it there are so many subtleties that will make your results meaningless. " Thanks for sharing your thoughts on refraction, I think this is the most important "uncertainity" factor of the experiment.

MrMaker, as I pointed out that this 3rd measurement at dawn (4AM to 6AM app.) was a very unusual. Later we foulnd out at modelling that our laer hit the water around 1500 meters from the shore. So this is not refraction, but reflexion! (I named the folder reflexion on the google drive not to make confusion with the other ones) we went off the corse of the laser path and missed the point where it was hitting the water, as we got back on track the beam was very low. In a short distance it was rising upwards and passed above our heads. From the Canon camera it looked like a huge refraction, but from the laser position it was fine. So the horizontal trembling laser was reflected on water surface and therefore did not have vertica movements (significant). I absolutely agree that beam distorsion is the key of the measurement precision. Scienceforum is my notepad I will discuss the subjects mentioned here from the forum directly with the Hungarian scientist too. Thank you for the very usefull and extensive information to all.

I aggree I will not look for that article of 0.4mm/km as it was probably not the same question we are discussing here. The 11mm volume seems reasonable to me. I only have a worry if the refraction can be estimated or not - as it varies very much in local conditions. The calculation of refraction on each measurement would be preferable as the measurement route is more than 2 hours. Conditions change a lot over time. "This is why I keep recommending obtaining the services/advice of a professional surveyor." Absolutely aggreed and I am taking that advice

Okay I give the definition for "we" used in the above text. WE as: Leader of the experiment: Sandor Szekely My partners in developing and evaluating the experiment: Zack M'rabbet (AutoCad and film), Steve Torrence (3D animation) Special guests on the experiment: Dave Moor and Nicu Buricu Laserist Mina (goldlaser.hu) and her employee Sandor Szemendri, the captain of theBoat and some other people. laser curvature experiments, as this was nr.2 as title of the video. We had a pre-test measurment 1 month before (video on the same channel) We will continue to make more measurments (improved with ideas from here as well) on the lake Balaton and over land also. EDIT here to make it more clear: This section above is "we". this next section is the theoretical expansion of the "we" in the future: We will more likely work together with a university - if that cooperation agreement is signed I will proudly present it. I have spoken with the leader of the LIDAR experiment 2 days ago - as I heard that he had been disinformed. (He is not even working at the same university as I am in contact with.) He told me that he will send me the complete (open access) database of the very same route LIDAR measurement as we had in our experiment. I will share for evaluation here as soon as I have them. As his office is located near the site of the experiment he said he might be able to visit us on the next upcoming experiment. We always announce our experimental dates and locations and we WELCOME everybody who has the possibility to visit us.