Automatically Calculate Geometry of Points in Web Mercator

[BenWagner3]

I'm working in an Enterprise Geodatabase (Enterprise Version 11.3), and I have a point feature class that is in Iowa State Plane North. I currently have attribute rules that run on Insert and Update to calculate the Northing and Easting of the points. I have been asked to also include attribute fields called Latitude and Longitude and have those fields automatically calculate the Y & X values in Web Mercator. I don't believe that Arcade in an attribute rule can handle that process. I have tried creating a scheduled process to calculate the geometry, but so far my Python scripts have been generating values that aren't remotely close to being correct.

I would prefer not to have to manually run the Calculate Geometry tool, like I have the past couple of days.

Does anyone have pointers on how to write a Python script that would calculate the X & Y in Web Mercator?

Thanks!

[CameronRex1]

@BenWagner3 You can try the following (I am not entirely sure what Iowa State Plane North you are using, so I have assumed WKID: 3417). I have tested something similar in another state plane and was able to get correct results. (If you are using a different WKID, let me know and I can change it up.)

// === Projection parameters for NAD83 StatePlane Iowa North FIPS 1401 (US Feet) ===
var lat0 = 41.5;
var lon0 = -93.5;
var phi1 = 43.2666666666667;
var phi2 = 42.0666666666667;
var E0 = 4921250.0; // False easting (ft)
var N0 = 3280833.3333; // False northing (ft)

// GRS80 ellipsoid
var a = 6378137.0;
var f = 1 / 298.257222101;
var e = sqrt(2 * f - f * f);

// === Helper functions ===
function rad(d) { return d * PI / 180; }
function deg(r) { return r * 180 / PI; }
function m(phi) {
return cos(phi) / sqrt(1 - pow(e, 2) * pow(sin(phi), 2));
}
function t(phi) {
return tan(PI / 4 - phi / 2) / pow((1 - e * sin(phi)) / (1 + e * sin(phi)), e / 2);
}
function inverseLCC(x, y) {
var phi1_rad = rad(phi1);
var phi2_rad = rad(phi2);
var lat0_rad = rad(lat0);
var lon0_rad = rad(lon0);

var m1 = m(phi1_rad);
var m2 = m(phi2_rad);
var t0 = t(lat0_rad);
var t1 = t(phi1_rad);
var t2 = t(phi2_rad);

var n = (log(m1) - log(m2)) / (log(t1) - log(t2));
var F = m1 / (n * pow(t1, n));
var r0 = a * F * pow(t0, n);

var r = sqrt(pow(x - E0, 2) + pow(r0 - (y - N0), 2));
var t_p = pow(r / (a * F), 1 / n);

var chi = PI / 2 - 2 * atan(t_p);
var lat_rad = chi + (e*e/2 + 5*pow(e,4)/24 + pow(e,6)/12) * sin(2*chi)
+ (7*pow(e,4)/48 + 29*pow(e,6)/240) * sin(4*chi)
+ (7*pow(e,6)/120) * sin(6*chi);
var lat = deg(lat_rad);

var theta = atan((x - E0) / (r0 - (y - N0)));
var lon = lon0 + deg(theta / n);

return [lat, lon];
}

// === Get point coordinates from the feature ===
var x = $feature.x;
var y = $feature.y;

// === Convert to Lat/Lon
var latlon = inverseLCC(x, y);

// === Format output
"Lat: " + Text(latlon[0], "#.######") + ", Lon: " + Text(latlon[1], "#.######")

[MOBrien2]

Is there any chance you could do this with WKID 2260 (New York East US Feet)? It uses Transverse Mercator projection instead of Lambert Conic Conformal (2SP). I can copy all the details down from the projected coordinate system definition, but Transverse Mercator uses scale factor instead of standard parallels which means the phi variables wouldn't work the same. I wish Esri would come up with a set of scripts for the different projection methods to do this.