RTK Coordinates from Phone to WGS84 Dec Deg using ITRF00 Transformation and proj4.js

Question

I am attempting to simulate an RTK GPS unit transmitting a CORS corrected GPS location to a phone. The coordinates are in NAD83 (from CORS) but in the phone they are seen in decimal degrees. I need to get the coordinate from NAD83 to WGS84 in order to properly place the location on the map (which uses the WGS84 datum). I want to use the ITRF00 transformation, with the definitions coming from the latest ArcGIS Desktop 10.7 and adjusted with input from here.

The problem I am having is when I do the transformation the output is not in decimal degrees, and if I convert back to wgs84 with no transformation, the result is not transformed.

var nad83 = "+proj=longLat +ellps=GRS80 +datum=NAD83 +towgs84=-0.9956,1.9013,-0.5215,0.025915,0.009246,0.011599,-0.00062 +units=degrees +no_defs"
var nad83NoTransform = "+proj=longLat +ellps=GRS80 +datum=NAD83 +towgs84=0,0,0 +units=degrees +no_defs"

Here are my efforts -

https://codepen.io/getbounds/full/BaaEVKy

If there is another library that can do this let me know. This needs to be done in the browser.

Answer 1

If you want to choose a different transformation than the built-in transformation, you need to omit the +datum= option - this overrides the +towgs84= option. See the above codepen for the solution.