Wondering if you can help me put together a paragraph with an explanation and/or graphics to help people understand why an LDP for NY State (via SPCS2022) would be beneficial?
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In the onset of the SPCS2022 projection, we are trying to put together a poll to determine if a third layer or LDP would be essential for NY State land surveyors and other stakeholders. My problem, I don't think most surveyors understand State Plane Coordinates or see the benefit that a Limited Distortion Projection would offer. From my experience, most surveyors tend to steer away from SPC. Whereas an LDP with distortion from the grid to the ground that is very minimal - would be a great benefit for surveyors; allowing boundary plats with ground distances to be more in harmony to an SPC system (needed only a Basis of Bearing rotation).?ÿ
Below are examples of current distoration and NGS possible changes.?ÿ
I would recommend?ÿ cribbing something from the Oregon OCRS paper.?ÿ One additional thought:?ÿ I wouldn't base leadership decisions on a poll.?ÿ The standards for licensure and geodetic knowledge being as low as they are, it is my experience that most surveyors and GIS pros are not in a position to hold a well informed opinion on this topic (members of this forum excepted, of course).?ÿ?ÿ
Another good resource is Appendix E of this paper https://www.ngs.noaa.gov/PUBS_LIB/NGSRealTimeUserGuidelines.v2.1.pdf .?ÿ?ÿ
Lee,
I know NYSAPLS moves slow, but this looks like something Greg de Bruin would make a priority. Are you working with anyone else on the project?
ARS, That's my thought also.
Yes, I am working with Greg, Duane F., David Z. and others from NYSAPLS. They want the poll to let the members decide. But as noted here, most NYSAPLS members do NOT use SPC, and/or do not understand an LDP. Hence my reason for this post. I want to try to educate the members why an LDP is useful for Land Surveyors.
From what I'm NYSDOT doesn't want to take the time to create LDP's. I want to move forward and willing to help as much as possible with or without NYSDOT.
The NAD 83 state plane for Long Island looks like a pretty good LDP itself. Distortion at the central parallel is only -5.1 parts per million, with maybe a 100-meter height variation overall.
Do Long Island surveyors use it without adjustment for any purposes? Maybe there is useful material from their experience.
MathTeacher,
Yes, distortion like that on Long Island is the goal for the rest of the state. One thought is an LDP for each of the 62 NY counties.
It's beneficial not to have to deal with grid vs. ground differences for all intents and purposes. What other reasons would one need??ÿ
Indiana has a system of zones by County. Each County has a zone, there is a zone named after every county. But in many cases the zone definitions are identical for adjoining counties. So there are actually fewer zones in the state than there are counties.
I just can't think of any legitimate excuse for not having LDPs other than simple fear of change.
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This. If private surveyors with private clients don't wanna use them then don't. But don't block the rest of us from moving forward.
Every time I read the March 23 documents, I end up confused, but I think that the 62 separate ones would not be designed by NGS. Their design would be up to NY stakeholders, to be approved by NGS.
See page 11 of the Procedures document: https://www.ngs.noaa.gov/INFO/Policy/files/SPCS2022_Procedures_NGS_2019-1214-01-A1.pdf
Did I read that correctly?
Yes, that's correct. NGS is willing to design 1 statewide and replacement SPC/SPCS zones. A third layer of large scale projected coordinate reference systems is up to the state agencies.
MathTeacher; You state the?ÿ "March 23 documents". Did I miss something? The document you linked to has a
date of?ÿ 4/23/2019. IF there is another paper of 23 March of year xxxx?ÿ can you list it for me.
Thanks
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JOHN NOLTON
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PS?ÿ?ÿ on page 10 of your link ( Procedures for Design and Modification of the State Plane Coordinate System of 2022)
NGS ?ÿhas an error in 1/f ?ÿto 18 significant digits. The last 3 digits they have are "744". ?ÿSee pg 10 last 2 lines of 6.b.i.
The 7 is correct but the 44 is wrong.
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Yeah, it's April, not March. There are two papers, one for Policies and another for Procedures, both dated April. You really have to read them both, but be sure to read the final versions instead of the draft versions.
I get all tangled up in the difference between a "zone" and a "layer" and how many zones and layers are permitted. Not to mention the "linear distortion design criterion" which has to satisfy three three minimum percentages simultaneously, including one decidedly moving target called population. So the 2020 census may affect state plane zones and/or layers in addition to all the stuff censuses already affect.
Age is taking its toll on my cognitive abilities. Perhaps it would all have been clearer to me 10 or 20 years ago.
Fortunately, I'm not a stakeholder, so I really don't have to understand.
If you haven't seen this, there is some good language at numbers 8 and 9.
https://www.ngs.noaa.gov/web/science_edu/webinar_series/QuestionResponses_webinar_2018-03-08.pdf
Fear of change is keeping us on the grid. We dont need 20th century approximations of the round earth anymore.
Oh man. Sounds like you drank the Earl Burkholder koolaid ????. Round earth surveying is all well and good, but getting stakeholders like engineers and contractors to get their heads wrapped around it is a major undertaking, let alone the dearth of software support.
I enjoy round earth survey comps as much as the next survey nerd, but it's map projections for the win until there is a sea change in software support and graphical presentation.
Software support is here. Carlson handles it well. I've heard Traverse PC does too. As far as engineers go, what they need is ground distances. Plane projections are hindrance to this, not a help. They can already use lat long to locate points.
Except in extreme cases how would contractors be impacted? They don't care how the distances and angles they are provided with were calculated.
