llh_converter::HeightConverter hc;

hc.setGeoidType(height_converter::GeoidType::GSIGEO2011); // Select Geoid Model
// hc.setGeoidType(height_converter::GeoidType::EGM2008);

hc.setGSIGEOGeoidFile(path_to_gsigeo_asc_file);   // Load geoid data file when you select GSIGEO
// hc.setGSIGEOGeoidFile();  // If called with void, it try to read /usr/share/GSIGEO/gsigeo2011_ver2_1.asc

double geoid_heith = hc.getGeoid(lat, lon);   // Get geoid heigth with latitude/longitude in decimal degree

// Convert height between ellipsoid and orthometric
double converted_height = hc.convertHeight(lat, lon, h, height_converter::ConvertType::ORTHO2ELLIPS);
double converted_height = hc.convertHeight(lat, lon, h, height_converter::ConvertType::ELLIPS2ORTHO);

llh_converter::LLHConverter lc;
llh_converter::LLHParam param;  // parameter for conversion
param.use_mgrs = true;          // set true if you want to use MGRS
param.plane_num = 9;            // set the plane number when you use JPRCS
param.mgrs_code = "53SPU";      // MGRS grid code is required when you revert MGRS x/y into lat/lon
param.height_convert_type = llh_converter::ConvertType::ELLIPS2ORTHO;
                                // You can also convert height
param.geoid_type = llh_converter::GeoidType::EGM2008;
                                // Set geoid model

double lat_deg, lon_deg, alt;
double lat_rad = lat_deg * M_PI / 180.;
double lon_rad = lon_deg * M_PI / 180.;
double x, y, z;

lc.convertDeg2XYZ(lat_deg, lon_deg, alt, x, y, z, param);
lc.convertRad2XYZ(lat_rad, lon_rad, alt, x, y, z, param);

lc.revertXYZ2Deg(x, y, lat_deg, lon_deg, param);
lc.revertXYZ2Rad(x, y, lat_rad, lon_rad, param);