I track relative positions to known fixed reference location (Lat/Lon/Alt on WGS 84).
Which means Location_0 is the above reference location, and Location_i is something like (X,Y,Z) relative by definition to Location_0 under ECEF convention (one can think about something like INS/IMU system).
But if the "distance" (for the sake of simplicity let's relax the definition of what exactly I mean by 'distance') between Location_0 & Location_i going as far as hundreds of kilometers etc. ECEF & NED assumptions not enough and I need to work with WGS 84.
How can I track positions calculated under ECEF NED assumption relatively to known referenced point on WGS84, and then convert them to WGS84?