Any Las Vegas surveyors here?

The zone definitions imply State Plane Coordinates, which are a projection of NAD83, currently. This document likely will answer your question:

https://files.lasvegasnevada.gov/public-works/Nevada-Coordinate-Reference-System-PDF.pdf

Or this:

https://www.leg.state.nv.us/nrs/NRS-327.html

Here is a map of all NAD83 projected State Plane Coordinate zones across the US.

I'm not a Nevada surveyor, but if you google search "NGS datasheets" you will quickly find yourself the link to the "NGS Map". Navigate on the map to your area of interest and double click on any control monument shown. A box will pop up with a link to the data sheet for that point. That datasheet will (usually) include state plane coordinates on the point, labelled with the appropriate zone.

'Vegas in in the eastern part of the state, the extreme southeast part, so I think you will find that the east zone is the one you want.

Thanks - looks like it is not Nevada East

I have a control point out on I15 - APEX_T1, 36°20'21.57101", -114°55'53.25968", 2411.430

Nevada East would give APEX_T1, 26825786.997, 848150.920 ,2501.336 I believe

But I am also given that it is APEX_T1, 107562.975, 124074.365, 2499.024

Anyone recognise what system might give N&E numbers in that range?

The SP coordinates you have computed look appropriate. The "2501" elevation you report is likely NAVD88 datum, while the "2499" elevation is likely NGVD29 datum. The difference is appropriate for that area.

A google search of "Nevada Low Distortion Projection" has produced a document detailing a couple of Las Vegas area projections.

Nevada Coordinate Reference System (NCRS)
Specifications

Datum

North American Datum of 1983 (NAD 83)

GRS 80 Ellipsoid

Parameters: a = 6378137 (exact)
1/f = 298.25722210088

Low-distortion Projections (LDP’s)

Las Vegas Zone
(NCRS, Las Vegas Zone)

Transverse Mercator Projection
Standard Parallel & Grid Origin: 36°15’00” N

Central Meridian: 114°58’00” W

False northing: 200,000 m
656,166.6667 feet (US)

False easting: 100,000 m
328,083.3333 feet (US)

Standard Parallel Scale: 1.0001 (exact)

Las Vegas High Elevation Zone
(NCRS, LV High Elev Zone)

Transverse Mercator Projection

Standard Parallel & Grid Origin: 36°15’00” N

Central Meridian: 114°58’00” W

False northing: 400,000 m
1,312,333.3333 feet (US)

False easting: 300,000 m
984,250.0000 feet (US)

Standard Parallel Scale: 1.000135 (exact)

The differences in heights shown here:

Nevada East would give APEX_T1, 26825786.997, 848150.920 ,2501.336 I believe

But I am also given that it is APEX_T1, 107562.975, 124074.365, 2499.024

About 2.3' (assuming those are feet) is roughly the same as the difference between NAVD88 and NGVD29 shown on this datasheet.

https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=GR0905

The (Northing and Easting?) 107562.975, 124074.365 could be meters? Maybe projected from NAD27 if the elevation is in fact NGVD29? You might run the latitude and longitude through NCAT and ask for an output in SPC27? The 2411.43 height with the lat/lon could be an ellipsoid height as it is in the range of the geoid height separations in California, where I work.

https://geodesy.noaa.gov/NCAT/

Thanks again for the input Gents.

Having played around with the data, I'm pretty certain what I have been given is a construction site with a custom site calibration to arbitrary coordinates for a machine control base station.

No wonder my colleagues were scratching their heads.

Access is happy enough, but now to get Virtual World working with those numbers (if we can).

Hi Jim,

The City of North Las Vegas has its own custom projection.

Site is not letting me attach the PDF, but here's particulars:

CITY OF NORTH LAS VEGAS USER DEFINED TRANSVERSE MERCATOR

PROJECTION PARAMETERS:

CENTRAL MERIDIAN = 115°05' 53.00" WEST

LATITUDE OF ORIGIN = 36°15' 00.00" NORTH

ORIGIN NORTHING = 75000.0000 U.S. FEET

ORIGIN EASTING = 75000.0000 U.S. FEET

SCALE ALONG CENTRAL MERIDIAN = 1.000093468437

Dave

Sorry Jim, I’m chiming in a little late here, but it does appear you are in the City of North Las Vegas “Apex Industrial Park”. State Plane coordinates (if in NAD 83) would be ‘Nevada East Zone 2701’. A mute point now I know. Please contact me if I can be of any assistance.

@davidgstoll

Bingo!

That's it, thank you. My numbers are now to within 0.5

I would like to see the pdf - any chance you could email to jim dot cox at xtra dot co dot nz please ( yes that is do co, not dot com)

Another question - how would you do heights there? - in particular what units, and would you expect a geoid model?

Thanks heaps - if we ever should meet, the beers are on me

Hi Jim,

Your email address is a head scratcher, but I'll give it a try. If it doesn't work, you can email me by adding Gmail.com to my username.

Dave