How to enter Lat Lon from a plat

Nate The Surveyor

Well-Known Member
#1
I have a Plat, that says it has NAD 83 coords, (1997)
they are like this:
34°06'53.61114" N
94°19'05.17022" W

I want to enter them into the LS. Directly.
Arkansas South Zone.
I've got it set up for NAD 83 coords, on Page 1.
However, I can's seem to get it to set up for this format...
It wants 34↑06.xxxxxxxxxxx (Degrees, and decimal of minutes.)
I thought, I am sure that others would like to see this too, so if you could, spell it all out, so that those of us new to all this power, can participate. That is, how to set up the Epoch date correctly, and how to set the correct format for the page, and then how to enter the coords, etc.
Knowledge is power. Empower us, ok?

Thank you.
Nate
 

Darren Clemons

Well-Known Member
#4
How about using many of the online sites to convert that Lat/Long to your desired St Plane zone and enter them that way?
I have a couple different ones on my desktop at my office but they’re specific to Kentucky. I’d think there are some for most everywhere....
 

Matthew D. Sibole

Well-Known Member
5PLS
#5
Open your project in your typical state plane coordinate system. Go to page 1 and edit the coordinate system of that page to straight NAD83. Make Page 1 current. Go to Points and enter the coordinate as shown above.

I just added it the way you have shown above on mine and it came in just fine. My background map does not show the road names but it is just east of a lake about 55 miles northwest of Texarkana.
 

Matt Johnson

Well-Known Member
5PLS
#7
The GeoData in J-Field supports NAD83 (HARN) but I'm not sure which transformation option should be used for this.

CSYS-REGION_20180301-19.05.50.png


CSYS-TRANSFER_20180302-06.24.10.png


Regardless I would be unwilling to blindly accept using old coordinates like this without some sort of check first.
 

Shawn Billings

Shawn Billings
5PLS
#8
Create a new coordinate system.

Select North America>United States (USA)>NAD83(2011)

Set Epoch date to 1996. Use Custom Projection & Rename to change the name of the system from NAD83(2011) to NAD83(1996). Then Done. This system should appear in your coordinate list now.

Create a Page with the coordinate system set to NAD83(1996). Enter your HARN based Latitude and Longitude. Switch to a page with Arkansas South NAD83(2011).

I tested this against the NGS HTDP program. This is what NGS gave me:
Nate LL Conversion.png

The LS gave me:
Nate LL Conversion LS.png

Stake2 is the coordinate entered in NAD83(2011), Stake3 is the coordinate entered in NAD83(1996). Both are displayed as NAD83(2011). Of course there is no change from 2011-2011 for Stake2, however Stake3 shows a translation of about 0.095' from 2011-1996. The elevation difference is because the 2011 system I used is orthometric and the 1996 system I used is ellipsoid. I put a zero elevation in for both, so the 92' elevation change is the geoid separation.
 

Shawn Billings

Shawn Billings
5PLS
#9
I don't have time now, but I would need to research to find what epoch date should be used for your 1997 HARN position. Possibly 1997, but not necessarily. The two big CORS adjustments were CORS96(epoch 2002) and NAD83(2011 - epoch 2010). If you can put your hands on a data sheet maybe you can determine what epoch date to use. I selected 1996, but that's probably not right.
 

Shawn Billings

Shawn Billings
5PLS
#10
I believe CORPSCON uses the EPSG transformation to go from HARN to NAD83(2011), so from the selection Matt shows above, the third option may be worth trying too.
 
#15
Don’t ya hate it when that happens.....:(
My crew pulled up to a lot here in town last week.....told the client two weeks....was one day shy of two weeks when we pulled in driveway to see fresh flags all over the lot. Called the client and they say “oh, I had someone out yesterday”....:mad::mad:
Me: And here is your bill for our research and travel time. Hope you saved some money while wasting my time.
 

Darren Clemons

Well-Known Member
#16
Me: And here is your bill for our research and travel time. Hope you saved some money while wasting my time.
Totally agree toivo and I’ve tried that approach, but it’s virtually impossible to collect. Ends up wasting more time trying to collect than just moving onto something I can actually make money on.....
Of course, signed contracts or work orders are the best but admittedly we don’t do that very often, especially on small jobs.
 

Vladimir Prasolov

Well-Known Member
5PLS
#17
I have a Plat, that says it has NAD 83 coords, (1997)
they are like this:
34°06'53.61114" N
94°19'05.17022" W
...
Dear Nate,

J-Filed works fine with NAD83(HARN) coordinates. It exactly matches official NCAT tool.

Just define NAD83(HARN)@1997.0 epoch. I like Shawn approach too. It takes into account local point movements.

upload_2018-3-5_13-14-1.png


upload_2018-3-5_13-14-19.png


upload_2018-3-5_13-14-31.png


upload_2018-3-5_13-14-43.png