Did anyone attend the NGS webinar on March 8th? I signed up, ended up being out of office and couldn't get it to load on my phone, so hopefully it was recorded!
SHG
I attended. It was the best one hour treatment of the subject I have seen. Michael Dennis was the presenter, and yes it was recorded, will be available on the NGS website. This was basically Part 1; there's also a followup scheduled for April 12. Should be a good one.
This document was posted yesterday just in time for Michael's presentation. It was outstanding and well worth watching the recording when available.
https://geodesy.noaa.gov/library/pdfs/NOAA_SP_NOS_NGS_0013_v01_2018-03-06.pdf
Best to watch it before the April Part 2 webinar, where he will get into more details.
Thanks guys, I know Michael and I figured it would be excellent, look forward to the recording.
Thank you for posting the link to the new SPCS document. I had to miss the webinar due to a conference but plan to watch it as soon as it's available.
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Melita
The recording of the webinar is now available:
https://geodesy.noaa.gov/web/science_edu/webinar_series/2018-webinars.shtml
The recording of the webinar is now available:
https://geodesy.noaa.gov/web/science_edu/webinar_series/2018-webinars.shtml
Thanks, yes I recieved an e-mail from NGS too.
Question:
How many of you folks have watched the above (excellent) Webinar so far?
Okay, one more question;
What do you think of the proposal for "projecting" the 2022 SPC coordinates to the "topographical surface," as opposed to the current system of using the ellipsoidal surface?
Yeah...I know, that's somewhat of an oversimplification, but if you watched the Webinar, you know what I mean.
Loyal
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Michael Dennis is?ÿ a Rock Star. He can make what would be a boring webinar a real interesting hour.
Not only did I greatly enjoy the March 8th reel, but looking forward to next installment and partially through the new document.
Topo surface will be way to roll in east. I don't have a clue how it will work here, unless the zones are really-really-really-really-really small.
Maybe we can have a unique zone for each section?
Question:
How many of you folks have watched the above (excellent) Webinar so far?
Okay, one more question;
What do you think of the proposal for "projecting" the 2022 SPC coordinates to the "topographical surface," as opposed to the current system of using the ellipsoidal surface?
Yeah...I know, that's somewhat of an oversimplification, but if you watched the Webinar, you know what I mean.
Loyal
I haven't had time to watch, but will.
To answer your question, that is a VERY bad idea.?ÿ SPCs are SPCs!?ÿ Leave them alone.?ÿ If the NGS wants to adopt a new projection (with a new name) that projects the coordinates to the "topographic surface" more power to them; just don't call it SPCs.?ÿ We will work with SPCs for many years to come.?ÿ While SPCs are not foolproof, changing the SPC projections for the new datum would be a disaster because fools are so ingenious!
My $0.02 opinion, nothing more.
Check this out...
https://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_elevation
and do the math.
There are 29 states & the District of Columbia that have LESS relief than?ÿSalt Lake City (5200 ft. within the City Limits)
Like Mark says, there are certainly States [back East] where this might work good (even great), but NOT out here in the West. I agree with Gene, it will be a recipe for disaster, there are too many folks who can't even deal with the State?ÿPlane System as it is!
Loyal?ÿ
It's interesting that Mr. Dennis chose North Carolina as one of his example states. Instead of defining the NC Lambert projection by two standard parallels, he defined it by fixing the central parallel and the scale factor on the central parallel. That's a concept that we discussed here a while back, noting that the same Lambert projection can be defined in either of the two ways.
We're not like the Rocky Mountain states,but we do vary in elevation from below sea level to more than 6,000 feet, so we do have distortion problems at the extreme ends of the state. The projection that Mr. Dennis described is only slightly different from the 83 version, but it will change coordinate values. He didn't mention the central meridian, so I assume that it stays at 79 degrees. It was all hypothetical, of course, but it does make an old math guy think.
I haven't looked at the math, but I suspect that there may be a fairly straight-forward transformation between the new and the old projections. Perhaps he will address that in the next webinar. In case he doesn't, I need to work on that now, 'cause I may not be around in 2022.
?ÿ
It's interesting that Mr. Dennis (or is it Dr. Dennis now?) chose North Carolina as one of his example states. Instead of defining the NC Lambert projection by two standard parallels, he defined it by fixing the central parallel and the scale factor on the central parallel. That's a concept that we discussed here a while back, noting that the same Lambert projection can be defined in either of the two ways.
We're not like the Rocky Mountain states,but we do vary in elevation from below sea level to more than 6,000 feet, so we do have distortion problems at the extreme ends of the state. The projection that he described is only slightly different from the 83 version, but it will change coordinate values. He didn't mention the central meridian, so I assume that it stays at 79 degrees. It was all hypothetical, of course, but it does make an old math guy think.
I haven't looked at the math, but I suspect that there may be a fairly straight-forward transformation between the new and the old projections. Perhaps he will address that in the next webinar. In case he doesn't, I need to work on that now, 'cause I may not be around in 2022.
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It's interesting that Mr. Dennis (or is it Dr. Dennis now?) chose North Carolina as one of his example states....
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North Carolina was the state that initiated the development of the whole State Plane system back in the '30s.?ÿ So it's appropriate to go back to that point when discussing new concepts.?ÿ?ÿ?ÿ
I watched the recording today.
I don't see their proposed methods as creating any new problems.?ÿ It is still an SPC just like the old ones except for the scale factor (and trivial changes in origin, etc.).?ÿ The talk about topographic surface means that they pick a scale factor that better fits the ground elevations in the zone instead of a scale factor that fits the ellipsoid.?ÿ Knowing that factor, you can still correct for differences in elevation just like you do now to bring distances to ground when the distortion is more than you can tolerate.?ÿ
You can still make modifrickinfied ground coordinates and Loyal and I will harp at you to knock off the millions and hundred thousands so it is obvious they aren't pure SPC.
This doesn't fix the whole problem for zones with a lot of elevation relief but it doesn't hurt them either, and it does help flatter areas.
I'm hoping that their "layer" stuff means that Iowa gets a whole-state SPC and 14 sub-zones matching up with the present Iowa Regional Coordinate System, and that NGS supports this by putting both sets of coordinates in the data sheets and OPUS reports.
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You can still make modifrickinfied ground coordinates and Loyal and I will harp at you to knock off the millions and hundred thousands so it is obvious they aren't pure SPC.
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but the kids will just add it back!?ÿ seriously.
better to create a new grid, and provide meta data on how you got there.
I used the scale factor and the central parallel that Michael Dennis gave for a no-state-contact Lambert SPCS for North Carolina to try to reproduce his projection. The scale factor on the central parallel is 0.99996 and the central parallel is 35?ø 15' north latitude. I assumed that the central meridian would remain at 79?ø west longitude, the grid origin would remain at 33?ø 45', and the Easting for the central meridian remains 609,601.2199 meters.
For EZ4026, a height modernization station not too far from me, I get N = 249,672.412 meters, E = 527,246.721 meters for the 2022 coordinates. These compare to N=249,650.654 meters, E = 527,253.952 meters for NAD 83 (2011) coordinates.
For DE9230, another height modernization station nearby, the 2022 coordinates are N = 252,129.133 meters, E = 529,717.478 meters for 2022 coordinates and N = 252,107.158 meters, E = 529,724.494 meters for NAD 83 (2011).
I do all of this stuff on an Excel spreadsheet. Would someone with good software like Blue Marble or something else mind checking these coordinates??ÿ
I think that stepping through this process with NGS could be a very valuable learning exercise.
This forum is just so far ahead of the curve, it's scary sometimes. Two years ago, we discussed the equivalence of tangent and secant Lambert conformal projections and now that concept turns up as the basis for Lambert state planes under the 2022 NGS scheme. Here's a link to our previous discussion:
https://surveyorconnect.com/community/software-cad-mapping/ldp-site/paged/2/#post-353543
Below is a Well-Known Text version of .prj file that demonstrates the concept for the current North Carolina State Plane Coordinate System. This one works on DNRGPS. Other GIS or CAD systems may have different requirements; I'm a retired school teacher who can't afford fancy stuff. Anyway, it might be interesting to try this file or a modification thereof in anticipation of the 2022 changes.
As a test, try converting DE9230 to NCSPCS coordinates using both your current file and this one. You should get the same results even though this file does not contain either of the standard parallels.
Thank you @MKennedy for the help. The number of ways that I can screw up a text file is amazing.
PROJCS["Lambert_Conformal_NC_1986_SF",
GEOGCS["GCS_North_American_1983_2011",
DATUM["D_North_American_1983_2011",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["Latitude_Of_Origin",35.2517586002],
PARAMETER["Scale_Factor",0.999872591882],
PARAMETER["False_Easting",609601.2199],
PARAMETER["False_Northing",166589.9922],
PARAMETER["Central_Meridian",-79.0],
UNIT["Meter",1]]
Note that the latitude of origin and scale factor come from the tables in NGS manual 5. Both were computed from the secant parallels and all of the significant digits are required in order to replicate state plane coordinates. The 2022 definitions will be cleaner; a large number of significant digits will be required if a secant equivalent is used.
For example, the quickly-done NCSPCS 2022 in the March 8 webinar with central parallel 35.25?ø and scale factor 0.99996 can be replicated with a secant projection with Southern Std Parallel = 34.73582798416670?ø and Northern Std Parallel = 35.76306791722220?ø. The fact that the scale factor along these parallels is equal to 1.00000000 really is insignificant.
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