gmh5225/wgs-wgs_conversions

A ROS server implementation of the World Geodetic System (WGS) conversion functions for converting to/from LLA, ENU, and ECEF.

wgs_conversions

A ROS server implementation of the World Geodetic System (WGS) conversion functions for converting to/from LLA, ENU, and ECEF.

Available Services

xyz2lla

Converts from ECEF coordinates (in meters) to Latitude, Longitude, Altitude (in degrees).

lla2xyz

Converts from Latitude, Longitude, Altitude (in degrees) to ECEF coordinates (in meters).

lla2enu

Converts from Latitude, Longitude, Altitude (in degrees) to a local level frame of the East, North, Up convention (in meters).

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

enu2lla

Converts from a local East, North, Up frame (in meters) to Latitude, Longitude, Altitude (in degrees).

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

xyz2enu

Converts from ECEF coordinates (in meters) to East, North, Up (in meters).

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

enu2xyz

Converts from East, North, Up (in meters) to ECEF (in meters).

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

xyz2enu_vel

Converts velocities from ECEF coordinates (in meters/sec) to East, North, Up (in meters/sec).

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

enu2xyz_vel

Converts velocities from East, North, Up (in meters/sec) to ECEF (in meters/sec).

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

xyz2enu_cov

Converts covariance matrix (of both position and velocity) from ECEF coordinates to East, North, Up.

Note: This requires a reference LLA position to serve as the origin of the local ENU frame.

enu2xyz_cov

Converts covariance matrix (of both position and velocity) from East, North, Up to ECEF.

Note(1): This requires a reference LLA position to serve as the origin of the local ENU frame.

Note(2): If you are working in North, East, Down (NED) convention and want to convert an ECEF covariance into NED, the enu2xyz_cov service can still be helpful. Just rotate the ENU covariance to NED using

P_ned = R P_enu R'

where P_enu is the ENU covariance (returned from enu2xyz_cov), P_ned is the NED covariance, R is a 3x3 matrix that represents the transformation from ENU to NED (shown below), and R' is the transpose of R.

R = [0  1  0]
    [1  0  0]
    [0  0 -1]

Usage

To familiarize yourself with using the ROS services, see the code in the example directory. This directory contains examples of a C++ and a python client.

From the workspace directory, run catkin_make with BUILD_EXAMPLE option set to ON

catkin_make -DBUILD_EXAMPLE=ON

Run the ROS server for WGS conversions

rosrun wgs_conversions wgs_conversions_server

In a new terminal, run the C++ example client

rosrun wgs_conversions wgs_conversions_client

Run the python example client

rosrun wgs_conversions wgs_conversions_client.py

To do

• Add UTM conversions
• Allow for NED local frame instead of ENU
• Reference position as a class variable

References

Decker, B. L., World Geodetic System 1984, Defense Mapping Agency Aerospace Center.

Author

Andrew Barrows (original MATLAB implementation). Dan Pierce (ROS/C++ implementation)

Maintainer

Dan Pierce (danpierce,[email protected])