llh_converter

(Updated 2025/03/17)

This repository has two class implementation.

• HeightConverter
• LLHConverter

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HeightConverter

Convert height between ellipsoid and orthometric library

Supported Geoid Models

• EGM2008-1
• GSIGEO2011 Ver2.1
• GSIGEO2024beta (Data file will be updated in 2025/04)

Usage

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 geoid data files under /usr/share/GSIGEO/

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);

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LLHConverter

Convert latitude/longitude/altitude into XYZ coordinate system.

Supported coordinate systems

• Millitary Grid Reference System (MGRS)
• Japan Plane Rectangular Coordinate System (JPRCS)
• Transverse Mercator with an arbitrary origin (TM)

Usage

llh_converter::LLHConverter lc;
llh_converter::LLHParam param;              // parameter for conversion
param.projection_method = llh_converter::ProjectionMethod::TM;
                                            // set the projection method TM/JPRCS/MGRS
param.plane_num = "9";                        // set the grid code for JPRCS/MGRS
                                            // for MGRS, it's required only when reverting to 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
// The following tm_param is required only when the projection method is TM
param.tm_param.inv_flatten_ratio = 298.257222101;
                                            // Set the inverse flattening ratio
param.tm_param.semi_major_axis = 6378137.0; // Set the semi-major axis
param.tm_param.scale_factor = 0.9996;       // Set the scale factor
param.tm_param.origin_lat_rad = 35.0 * M_PI / 180.;
param.tm_param.origin_lon_rad = 139.0 * M_PI / 180.;
                                            // Set the origin

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);

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meridian convergence angle correction

The meridian convergence angle is the angle of difference between true north and coordinate north.

The meridian convergence angle is calculated by the getMeridianConvergence() function.

Usage

  llh_converter::LLHConverter lc;
  llh_converter::LLHParam param;
  param.projection_method = llh_converter::ProjectionMethod::JPRCS;
  param.grid_code = "7";
  param.height_convert_type = llh_converter::ConvertType::NONE;
  param.geoid_type = llh_converter::GeoidType::EGM2008;

  llh_converter::LLA lla;
  llh_converter::XYZ xyz;
  lla.latitude = test_lat;
  lla.longitude = test_lon;
  lla.altitude = 30.0;
  llh_converter.convertDeg2XYZ(lla.latitude, lla.longitude, lla.altitude, xyz.x, xyz.y, xyz.z, param);
  double mca = llh_converter::getMeridianConvergence(lla, xyz, llh_converter, param); // meridian convergence angle

Install

sudo apt update
sudo apt install libgeographic-dev geographiclib-tools geographiclib-doc

sudo geographiclib-get-geoids best

mkdir -p test_ws/src
cd test_ws/src/
git clone https://github.com/MapIV/llh_converter.git
sudo mkdir /usr/share/GSIGEO
sudo cp llh_converter/data/gsigeo2011_ver2_1.asc /usr/share/GSIGEO/
unzip llh_converter/data/GSIGEO2024beta.zip
sudo mv GSIGEO2024beta.isg /usr/share/GSIGEO/
cd ../
catkin_make -DCMAKE_BUILD_TYPE=Release

Geoid model data

This package contains GSIGEO2011/GSIGEO2024 geoid data file which is provided by Geospatial Information Authority of Japan.

GSI's official website that relies on GSIGEO2011

GSI's official website that relies on GSIGEO2024

LICENSE

This package is provided under the BSD 3-Clauses License.