Yaml formats

Camera-system calibration (camchain.yaml)

This file stores the calibration of the camera intrinsic and extrinsic parameters as well as the spatial and temporal calibration parameters of the IMU with respect to the cameras.

Each camera has the following parameters:

camera_model
camera projection type (pinhole / omni)
intrinsics
vector containing the intrinsic parameters for the given projection type. elements are as follows:
pinhole: [fu fv pu pv]
omni: [xi fu fv pu pv]
see Supported models for more information
distortion_model
lens distortion type (radtan / equidistant)
distortion_coeffs
parameter vector for the distortion model
see Supported models for more information
T_cn_cnm1
camera extrinsic transformation, always with respect to the last camera in the chain
(e.g. cam1: T_cn_cnm1 = T_c1_c0, takes cam0 to cam1 coordinates)
T_cam_imu
IMU extrinsics: transformation from IMU to camera coordinates (T_c_i)
timeshift_cam_imu
timeshift between camera and IMU timestamps in seconds (t_imu = t_cam + shift)
rostopic
topic of the camera's image stream
resolution
camera resolution [width,height]

Example chain.yaml

cam0:
  camera_model: pinhole
  intrinsics: [461.629, 460.152, 362.680, 246.049]
  distortion_model: radtan
  distortion_coeffs: [-0.27695497, 0.06712482, 0.00087538, 0.00011556]
  T_cam_imu:
  - [0.01779318, 0.99967549,-0.01822936, 0.07008565]
  - [-0.9998017, 0.01795239, 0.00860714,-0.01771023]
  - [0.00893160, 0.01807260, 0.99979678, 0.00399246]
  - [0.0, 0.0, 0.0, 1.0]
  timeshift_cam_imu: -8.121e-05
  rostopic: /cam0/image_raw
  resolution: [752, 480]
cam1:
  camera_model: omni
  intrinsics: [0.80065662, 833.006, 830.345, 373.850, 253.749]
  distortion_model: radtan
  distortion_coeffs: [-0.33518750, 0.13211436, 0.00055967, 0.00057686]
  T_cn_cnm1:
  - [ 0.99998854, 0.00216014, 0.00427195,-0.11003785]
  - [-0.00221074, 0.99992702, 0.01187697, 0.00045792]
  - [-0.00424598,-0.01188627, 0.99992034,-0.00064487]
  - [0.0, 0.0, 0.0, 1.0]
  T_cam_imu:
  - [ 0.01567142, 0.99978002,-0.01393948,-0.03997419]
  - [-0.99966203, 0.01595569, 0.02052137,-0.01735854]
  - [ 0.02073927, 0.01361317, 0.99969223, 0.00326019]
  - [0.0, 0.0, 0.0, 1.0]
  timeshift_cam_imu: -8.681e-05
  rostopic: /cam1/image_raw
  resolution: [752, 480]

IMU configuration (imu.yaml)

IMUs are configured using a YAML file. Please refer to the example below for details:

imu.yaml

#Accelerometers
accelerometer_noise_density: 1.86e-03   #Noise density (continuous-time)
accelerometer_random_walk:   4.33e-04   #Bias random walk

#Gyroscopes
gyroscope_noise_density:     1.87e-04   #Noise density (continuous-time)
gyroscope_random_walk:       2.66e-05   #Bias random walk

rostopic:                    /imu0      #the IMU ROS topic
update_rate:                 200.0      #Hz (for discretization of the values above)