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Plat Narrative

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Loyal
(@loyal)
1,000+ posts Member

I came across this a couple of days ago, I particularly liked the "vertical datum" note (the Geoid height in this area runs around -15.5 meters).

Vertical
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Topic starter Posted : October 13, 2021 8:08 pm
RADAR, Jitterboogie, FL/GA and 2 people liked
Mark Mayer
(@mark-mayer)
1,000+ posts Member

Wow. Just ....  wow.

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Posted : October 13, 2021 9:59 pm
Gene Kooper
(@gene-kooper)
1,000+ posts Member

Well, if you had stayed retired you would have avoided this nitwittery.

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Posted : October 13, 2021 10:12 pm

Loyal
(@loyal)
1,000+ posts Member

@mark-mayer Ya can't make this stuff up! Actually I HAVE seen worse...much worse.

On the upside, it tells me more about his survey, than the author probably intended.

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Topic starter Posted : October 13, 2021 10:16 pm
JBStahl liked
Gene Kooper
(@gene-kooper)
1,000+ posts Member

@loyal And don't forget to to include the difference between NAVD88 and the U.S.G.S. elevations being in NGVD29 (assuming that they looked at spot elevations on a USGS quad sheet for the "U.S.G.S. elevations").

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Posted : October 13, 2021 10:21 pm
JBStahl liked
Loyal
(@loyal)
1,000+ posts Member

@gene-kooper Some of the U.S.G.S elevations (including both contours & Bench Marks) predate NGVD29 by quite a bit (1901 Topographic Map) and BMs which were stamped with the elevation and SLAK (Salt Lake Datum)

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Topic starter Posted : October 13, 2021 10:59 pm

Gene Kooper
(@gene-kooper)
1,000+ posts Member

@loyal I think you are being too generous with the extent of his research. With that narrative, it is more likely that he came across a 1950s or 1960s vintage USGS topo quad rolled up and stashed in a corner of his office.

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Posted : October 13, 2021 11:28 pm
JBStahl liked
paden cash
(@paden-cash)
10,000+ posts Supporter
Posted by: @gene-kooper

Well, if you had stayed retired you would have avoided this nitwittery.

I love this word.  I can't say as I have ever heard it before. 

ps - for some reason it seems a particularly comfortable fit in a discussion of land surveying... 😉 

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Posted : October 14, 2021 4:33 am
Shawn Billings
(@shawn-billings)
1,000+ posts Vendor

That's incredible. Like you said, this is actually very informative Metadata. 

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Posted : October 14, 2021 5:15 am

Rover83
(@rover83)
500+ posts Member

I've seen "Datum: GPS" quite a bit.

Concerning that note, it would seem to indicate that no geoid separations were applied and heights are ellipsoidal...which is something else I have seen a few times on topographic surveys. In this area the difference is ~70 USFt.

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Posted : October 14, 2021 5:58 am
MightyMoe
(@mightymoe)
5,000+ posts Member

The GPS thingy I'm guessing isn't the real problem. 

He found the original monuments and rejected them? "because of math"  That's a quote!!!!

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Posted : October 14, 2021 6:07 am
Jp7191 liked
BStrand
(@bstrand)
1,000+ posts Member

@mightymoe

He found the original monuments and rejected them? "because of math"  That's a quote!!!!

Yeah, I actually find that more amusing than the GPS bit.  Hopefully someone came along and got this guy up to speed pretty quick, changed careers, etc.

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Posted : October 14, 2021 6:40 am
Jp7191 liked

Norm Miller
(@norm)
500+ posts Member

@mightymoe 

If the math is ambiguous shouldn't the existing monuments hold more weight?  And we don't know if he's on grid or ground. We do know he's in GPS nirvana.

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Posted : October 14, 2021 6:51 am
Jp7191 liked
thebionicman
(@thebionicman)
1,000+ posts Member

The scary part is, the narrative worked. We all know exactly how he wrecked the boundary.

If this guy was in my town we'd have to talk.. 

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Posted : October 14, 2021 6:57 am
Rover83
(@rover83)
500+ posts Member
Posted by: @norm

And we don't know if he's on grid or ground.

And who knows what that "grid" could be and what projection it was derived from. I once came across an azimuthal projection...

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Posted : October 14, 2021 7:06 am

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