Use geographiclib to generate 3d points - geographic-distance

Question

Can geographiclib be used to convert (WGS84) latitude-longitude pairs to 3d/Cartesian/xyz points?
If not, is there an alternative method for converting from one to the other without using a spherial approximation?

Answer 1

Yes. As the following example shows, the Geographiclib::Geocentric class provides such a conversion:
// Example of using the GeographicLib::Geocentric class
#include <iostream>
#include <exception>
#include <cmath>
#include <GeographicLib/Geocentric.hpp>
using namespace std;
using namespace GeographicLib;
int main() {
try {
Geocentric earth(Constants::WGS84_a(), Constants::WGS84_f());
// Alternatively: const Geocentric& earth = Geocentric::WGS84();
{
// Sample forward calculation
double lat = 27.99, lon = 86.93, h = 8820; // Mt Everest
double X, Y, Z;
earth.Forward(lat, lon, h, X, Y, Z);
cout << floor(X / 1000 + 0.5) << " "
<< floor(Y / 1000 + 0.5) << " "
<< floor(Z / 1000 + 0.5) << "\n";
}
{
// Sample reverse calculation
double X = 302e3, Y = 5636e3, Z = 2980e3;
double lat, lon, h;
earth.Reverse(X, Y, Z, lat, lon, h);
cout << lat << " " << lon << " " << h << "\n";
}
}
catch (const exception& e) {
cerr << "Caught exception: " << e.what() << "\n";
return 1;
}
}