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The sort of ignorant practice he’s trying to defend is only done by people who have no knowledge of what they are doing, who create errors the rest of us have to come along and fix.
Let me see, all of you keep on saying my procedure is wrong, and yet not even one of you could even provide a link that says the method
is wrong. Hmmm, I guess all of you also saw Bigfoot I would guess.Sean Ora, post: 421153, member: 12254 wrote: Let me see, all of you keep on saying my procedure is wrong, and yet not even one of you could even provide a link that says the method
is wrong. Hmmm, I guess all of you also saw Bigfoot I would guess.Hey, thanks for outing yourself FrancisH! :rofl:
And don’t go dissing our Bigfoot!
You have your mythological monster in Loch Ness (for when your worldly travels bring you to England).Otherwise, watch out for Hantu Air when out with your RTK rover in the boat.
Bill93, post: 421013, member: 87 wrote: I’ve read a little more in the referenced FIG paper. It seems they are defining chart datums that allow the user to go directly from GNSS measurements and tide info to the ocean depth at a location. The user does not need or use orthometric elevations or geoids because all the necessary information, including the variation induced by gravity, is in the chart.
Rather than saying geoids are irrelevant, on page 20 it talks about using a geoid model to interpolate between measured points for the separations of the chart.
There is also this relevant statement on p. 20.
“A simple SEP shift can be determined … This single value can be used in the local area only, where the assumption that the spatial variation in chart datum, geoid, and TSS [topography of sea surface] is at a minimum.”This means that the method proposed by FrancisH, whereby he considered ellipsoidal height and orthometric elevation to be equally usable without geoid corrections, is limited in its applicability, perhaps to regions such as a harbor or small bay.
That’s pretty much what several of us were telling him – that it was an approximation that would work for some applications, but not all, and one should understand its limitations.
Thanks Bill.
Gene Kooper, post: 421160, member: 9850 wrote: Hey, thanks for outing yourself FrancisH! :rofl:
And don’t go dissing our Bigfoot!
You have your mythological monster in Loch Ness (for when your worldly travels bring you to England).Otherwise, watch out for Hantu Air when out with your RTK rover in the boat.
Sure, talk all day long but I guess that’s all you really do once you have been called out regarding your lack of knowledge.
Talk talk talk. I guess this was your first time to read the FIG paper right? Didn’t even know you could transfer heights
directly to chart datum right?
Or maybe you are from those land locked county that have not even stepped out to see the sea…Sean Ora, post: 421153, member: 12254 wrote: Let me see, all of you keep on saying my procedure is wrong, and yet not even one of you could even provide a link that says the method
is wrong. Hmmm, I guess all of you also saw Bigfoot I would guess.It’s not something that needs a link. It might surprise you, but all this stuff was worked out before the internet came along.
Anyway, there is enough information out there – if you are not capable of reading it and understanding it that’s not my problem.
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In The Sandpit, post: 421210, member: 99 wrote: It’s not something that needs a link. It might surprise you, but all this stuff was worked out before the internet came along.
Where have you been this last decade? If it’s not on Google, it does not exist.
Well I have been waiting for more than 24 hours for the US surveying creme de la creme to please show me some reference
to point out the errors in my humble surveying practice. Well no one was able to provide such proof. Others talk talk talk while
another used a double negative as proof positive (?).As the adage goes, PUT UP or SHUT UP. I guess all of you just SHUT UP huh?
Sean Ora, post: 421213, member: 12254 wrote: Where have you been this last decade? If it’s not on Google, it does not exist.
Well I have been waiting for more than 24 hours for the US surveying creme de la creme to please show me some reference
to point out the errors in my humble surveying practice. Well no one was able to provide such proof. Others talk talk talk while
another used a double negative as proof positive (?).As the adage goes, PUT UP or SHUT UP. I guess all of you just SHUT UP huh?
Don’t need to mate, the old saying about never arguing with fools applies in this case. Unfortunately you don’t have the tools for this discussion, and it’s not my job to educate you[emoji1]. No one really cares how you do it, that’s a matter for you and your professional indemnity insurance carrier. Although I’m guessing you probably don’t know what that is either.
Enjoy.
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In The Sandpit, post: 421214, member: 99 wrote: Don’t need to mate, the old saying about never arguing with fools applies in this case. Unfortunately you don’t have the tools for this discussion, and it’s not my job to educate you. No one really cares how you do it, that’s a matter for you and your professional indemnity insurance carrier. Although I’m guessing you probably don’t know what that is either.
Enjoy.
Talk talk talk talk talk talk.
But can’t really find a reference.
I would venture to bet that you don’t even know what a chart datum is or how to convert tidal readings to chart datum. Never even knew what
a tidal gauge is or how it works.
Keep on talking mate.From:
NOS HYDROGRAPHIC SURVEYS SPECIFICATIONS AND DELIVERABLESMarch 2016
USDOC/NOAA
The determination of an ellipsoid height is hardly the only requirement. The referenced document as well as the NOAA Field Operations Manual are available for free download. See: https://www.nauticalcharts.noaa.gov/hsd/fpm/fpm.htm
Wow, this thread is like a train wreck. I know I should not look at the carnage but I just can’t help it.
Sean and/or Francis,
I’m not saying your method will does not produce results, I’m saying that you are leaving a substantial amount of your error budget on the table. Kind of like reading an antenna height to the nearest decimeter when it has millimeter graduations. While this may be hidden by the accuracies associated with sonar, the error is still there. As I stated in an earlier post, before the days of densified geoid models we would use your method on very small areas. As the areas increased in size we would start to tie BM’s in an effort to model the geoid more accurately. Depending on the geology of the area you are working the geoid can change quite rapidly in a short distance. Given the improvement of geoid models over the decades, it is not as necessary to refine the geoid by measurements on multiple BM’s. Even if you are holding a single tidal station elevation, you may improve your final results by taking the gravitational model into account.As for my processing background, I started out post processing GPS data commercially with TrimVec back in 1993 after I left the government agency that brought you WGS83 and EGM. Since then I have used numerous static/ppk/RTK software packages to provide geodetic control for NOAA, inland hydrographic surveying, airborne GNSS/IMU positioning and various other tasks associated with our engineering design survey work.
John Putnam, post: 421252, member: 1188 wrote: I’m not saying your method will does not produce results, I’m saying that you are leaving a substantial amount of your error budget on the table. Kind of like reading an antenna height to the nearest decimeter when it has millimeter graduations.
Let me see, that statement seems a lot different from
Ignorance may be bliss, but it does make for some odd page views:
Duh, it’s called inflating the ellipsoid. Clearly you don’t have much experience or education it GNSS or Geodesy. You should really stop, we are all laughing at you. (unless that’s what you are after?)
Let me say this one more time, only a bit slower so you can follow along. Your method is an old stop-gap measure that makes the erroneous assumption that the geoid separation is a constant across a project. If you had taken any time in the last 20 years to educate yourself, you would have stopped using that archaic method.
So which is which? Do you even understand the concept of ellipsoidal transfers and its accuracy?
GeeOddMike, post: 421237, member: 677 wrote: The determination of an ellipsoid height is hardly the only requirement.
Maybe you haven’t read entire document. Next time please READ and UNDERSTAND. Those are 2 different things.
The Project Instructions will explicitly list any required subordinate tide gauges. A VDatum or constant separation file to correct soundings from the ellipsoid to chart datum will be provided on the project CD/DVD.
Survey wide data analysis can be performed relative to Ellipsoid or chart datum as most appropriate
4.2.5.1.2 Apply Ellipsoid to Chart Datum Separation Model (SEP) For the 2014 field season, the processes and tools for applying SEP to CARIS processed bathymetry grids are being developed. The process will involve the following basic steps: 1. Ellipsoidally referenced grid surfaces are read from CARIS. 2. Grid math is performed (currently outside of CARIS) to apply the project SEP model (VDATUM or ERZT) datum and datum uncertainty. 3. The adjusted surface data is read back into CARIS now referenced to chart datum (MLLW) with appropriate vertical datum transformation uncertainty applied.
Read read read understand understand understand.
Since then I have used numerous static/ppk/RTK software packages to provide geodetic control for NOAA, inland hydrographic surveying, airborne GNSS/IMU positioning and various other tasks associated with our engineering design survey work.
You can use any software available. You can input any value you like for heights and it will still process it for you.
Having access to various software does not mean you understand the concept behind the work required.
Another guy just gave reference to a NOAA document and apparently he also has not read or understood what procedures were
required and for what purpose.You want to talk about geoid? ok let’s talk about geoid. What’s the latest global geoid available? Is it the EGM 2008 from NGA?
Well from it’s web site, it seems that it’s resolution is about 1×1 minute grid. This means that everything within the 1 minute grid
will have the same value or is averaged from different sources of gravity readings.Anything smaller than this grid will be INTERPOLATED.
Now do you know how large a 1 minute grid is in real world scenarios?
It’s approximately 2km x 2km at the equator.Sean Ora, post: 421339, member: 12254 wrote: You want to talk about geoid? ok let’s talk about geoid. What’s the latest global geoid available? Is it the EGM 2008 from NGA?
Well from it’s web site, it seems that it’s resolution is about 1×1 minute grid. This means that everything within the 1 minute grid
will have the same value or is averaged from different sources of gravity readings.Anything smaller than this grid will be INTERPOLATED.
Now do you know how large a 1 minute grid is in real world scenarios?
It’s approximately 2km x 2km at the equator.Bilinear interpolation will not return a constant number or slope. Harmonic synthesis won’t either but the two will nearly match each other. Both are superior to the slop method of blanket adjustment. We pick on that method because it is too simple to do things correctly. As long as you stay on your island you can do what you want.
thebionicman, post: 421350, member: 8136 wrote: Bilinear interpolation will not return a constant number or slope. Harmonic synthesis won’t either but the two will nearly match each other. Both are superior to the slop method of blanket adjustment. We pick on that method because it is too simple to do things correctly. As long as you stay on your island you can do what you want.
OK….whatever you just said. I guess you are trying the ‘Sophisticated Technical’ approach to try to save face. I mean if you can’t even explain something
in plain english it simply means you don’t understand it in the first place.The manual from the NOAA site is a technical paper yet I understood it without all of your technical terms. I get it, you are trying to back track or save face
because all of you got caught by your own NOAA technical manual as well as the FIG technical procedure manual.Very talented group of american surveyors here. All talk talk talk talk talk.
Sean Ora, post: 420995, member: 12254 wrote: In our country, we throw away the creme that floats on top of the milk batter.
Which country is that? Because you are definitely not British.
Sean Ora, post: 421357, member: 12254 wrote: OK….whatever you just said. I guess you are trying the ‘Sophisticated Technical’ approach to try to save face. I mean if you can’t even explain something
in plain english it simply means you don’t understand it in the first place.The manual from the NOAA site is a technical paper yet I understood it without all of your technical terms. I get it, you are trying to back track or save face
because all of you got caught by your own NOAA technical manual as well as the FIG technical procedure manual.Very talented group of american surveyors here. All talk talk talk talk talk.
Therr are two primary methods of interpolation using global geoid models. Since you used ‘interpolation’ i simply pointed out that your own words invalidated the crude blanket adjustment method.
I have no need to save face. When you tell the truth and admit your shortcomings life is easy. You also learn. Try it, you might like it.Sean Ora, post: 421357, member: 12254 wrote: OK….whatever you just said. I guess you are trying the ‘Sophisticated Technical’ approach to try to save face. I mean if you can’t even explain something
in plain english it simply means you don’t understand it in the first place.Would you answer this please:
Why are you so rude, Sir?Gene Kooper, post: 421160, member: 9850 wrote: Hey, thanks for outing yourself FrancisH! :rofl:
And don’t go dissing our Bigfoot!
You have your mythological monster in Loch Ness (for when your worldly travels bring you to England).Otherwise, watch out for Hantu Air when out with your RTK rover in the boat.
Nessy moved to England? And please don’t say Scotland is England….
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