Lidar Calibration Settings

The calibration tab displays the sensor-to-IMU rotations and translations associated with the lidar. These settings can be modified via LiDARSnap, however it is not recommended to manually change these values.

Mounting Transform (IMU to Sensor)

These fields apply a transformation from the center of the IMU to the center of the LiDAR sensor. The Translation fields define the offset from the center of the IMU to the LiDAR’s optics. The Rotation (extrinsic ZXY order) fields define how the LiDAR sensor is oriented relative to the IMU.‌

• Translation - The translations (X,Y and Z) along the IMU axis between the center of navigation (IMU reference point) and the LiDAR reference point

• Rotation (XYZ order) - The rotations between the IMU frame and the LiDAR sensor frame

Mounting Calibration (IMU to Sensor)

These fields apply systematic IMU frame to sensor frame misalignment corrections commonly referred to as "boresight calibration" corrections

• Translation - Translation corrections along the IMU axis between the center of navigation (IMU reference point) and the LiDAR reference point

• Rotation (XYZ order) - LiDAR boresight misalignment corrections - IMU to sensor (roll, pitch, yaw

Encoder Calibration

Some sensors have their encoder mounted improperly, such that the center of encoder doesn't match the center of spin axis. This introduces an error when getting encoder reads, most of which manifests as a sine. Thus, a correction sine can be fit with phase and amplitude to the encoder readings.

• EEA - Encoder Error Amplitude (degrees)

• EEP - Encoder Error Phase (degrees)

Per-laser Calibration

These fields apply corrections to each laser individually

• Translation (XYZ) - Physical offset of the given laser to the center of sensor. Usually, X and Y will not be used and Z will be set to vertical offset on the spin axis for multilaser systems.

• Rotation (XYZ) - Per-laser rigid rotation calibration (applies to legacy calibrations)

• Range Scale - Applies a scale factor (multiplier) to the range reading.

• Range Offset - Applies an offset for the range reading.

  • Range scale and offset parameters will adjust the range such that: rangeNew = rangeOld * rangeScale + rangeOffset.

• Scan Angle Scale - Applies a scale factor (multiplier) to the scan angle reading. Scan angle is the angle in spin direction, as reported by the encoder

• Scan Angle Offset - Applies an offset for the scan angle reading. The offset is applied

  in spin-axis direction and is in degrees.

  • Scan angle scale and offset parameters will adjust the range such that: scanAngleNew = scanAngleOld * scanAngleScale + scanAngleOffset

• Tilt Angle Scale - Applies a scale factor (multiplier) to the tilt angle. Tilt Angle is the angle between the laser and the spin axis. Notice this will have a different effect than rotation, as it will not move the spin axis, rather it will adjust the angle between the laser and the spin axis.

• Tilt Angle Offset - Applies an offset for the tilt angle.

  • Tilt angle scale and offset parameters will adjust the range such that: tiltAngleNew = tiltAngleOld * tiltAngleScale + tiltAngleOffset.