Mapping Path data is stored in the trace.csv file for each Dataset. It provides high‑frequency samples of the mapping system’s trajectory, including timestamp, 3D position, quaternion orientation, and magnetic field vectors, all expressed relative to the dataset’s origin. This guide explains the structure and meaning of each field so you can correctly interpret and use trace.csv in your workflows.
For every Dataset, the file trace.csv contains position, orientation, and magnetic field information in frequent intervals. This is an example of what the file looks like:
#nsecs, x, y, z, ori_w, ori_x, ori_y, ori_z, mag_x, mag_y, mag_z
1478254247676381327, 8.84298e-07, 1.28572e-06, -0.2, 0.999992, 0.000376351, 0.00401342, 1.90039e-07, -6.51576e-07, -3.18442e-06, -3.36381e-05
1478254247783401487, 0.00150315, 0.000978242, -0.2, 0.999992, 0.000330729, 0.00398468, -6.80018e-05, -1.30323e-06, -3.18672e-06, -3.33109e-05This is the information contained in the fields
nsecs: The time in nanoseconds since 1/1/1970 00:00:00The following fields contain the location of the mobile mapping system, in meters from the dataset's origin:
x: The x-coordinates of the location.y: The y-coordinates of the location.z: The z-coordinates of the location.
The following fields contain the orientation of the mobile mapping system relative to the dataset's origin, expressed as a quaternion:
ori_w: The real part of the quaternion.ori_x: The x-component of the quaternion.ori_y: The y-component of the quaternion.ori_z: The z-component of the quaternion.
The following fields contain the magnitude of magnetic field in Tesla:
mag_x: The x-component of the magnitude.mag_y: The y-component of the magnitude.mag_z: The z-component of the magnitude.
FAQ
What is the purpose of the trace.csv file?
The trace.csv file stores mapping path data for each dataset, providing high-frequency samples of the mapping system's trajectory, including timestamp, 3D position, quaternion orientation, and magnetic field vectors.
What kind of data is included in the trace.csv file?
The trace.csv file includes timestamp, 3D position (x, y, z), quaternion orientation (ori_w, ori_x, ori_y, ori_z), and magnetic field vectors (mag_x, mag_y, mag_z).
How is the position data represented in the trace.csv file?
The position data is represented in meters from the dataset's origin, with separate fields for x, y, and z coordinates.
What does the quaternion orientation represent in the trace.csv file?
The quaternion orientation represents the orientation of the mobile mapping system relative to the dataset's origin, expressed as four components: ori_w, ori_x, ori_y, and ori_z.
What units are used for the magnetic field data in the trace.csv file?
The magnetic field data is expressed in Tesla, with separate fields for the x, y, and z components of the magnetic field.
What do the mag_x, mag_y, and mag_z values in trace.csv mean?
These fields represent the x, y, and z components of the magnetic field magnitude, measured in Tesla. They are part of the high-frequency trajectory data recorded in the trace.csv file for each dataset.