Open Cosmos Ancillary data format

Open Cosmos provides platform ancillary data in a JSON file with the same format as the following example:

{
  "version": "v0.2.0",
  "intrinsics": {
    "sensor_size_px": [4096, 3072],
    "sensor_size_mm": [22.528, 16.896],
    "pixel_size_mm": 0.0055,
    "focal_length_mm": 775,
    "principal_point_px": [2048, 1536],
    "aperture_mm": 77.5
  },
  "extrinsics": {
    "gnss_lock": "true",
    "hist": [
      {
        "time_s": 1663857341,
        "time_ns": 1183374,
        "interpolated": false,
        "attitude": {
          "w": 1,
          "x": -2.1177511633824e-11,
          "y": 1.02943626093807e-10,
          "z": 2.18008983922966e-21,
          "frame": 1
        }
      },
      {
        "time_s": 1663857344,
        "time_ns": 0183574,
        "interpolated": false,
        "position": {
          "x_m": -1158534.565687809,
          "y_m": -5718976.586116229,
          "z_m": 3641410.860961713,
          "frame": 2
        }
      },
      {
        "time_s": 1663857344,
        "time_ns": 2183344,
        "interpolated": false,
        "velocity": {
          "x_ms": 719.5879991115379,
          "y_ms": -4173.39814816362,
          "z_ms": -6325.542379961036,
          "frame": 2
        }
      },
      {
        "time_s": 1663857345,
        "time_ns": 4186374,
        "interpolated": false,
        "angular_rates": {
          "x_rads": 719.5879991115379,
          "y_rads": -4173.39814816362,
          "z_rads": -6325.542379961036,
          "frame": 2
        }
      }
    ]
  }
}

Intrinsics and Extrinsics components

Intrinsic Components: Intrinsic parameters are properties inherent to the sensor itself. These parameters define the sensor's internal characteristics and how it captures data, independent of its position or orientation in the real world.

Extrinsic Components: Extrinsic parameters describe the sensor's position, orientation, and motion in the real world. These parameters are essential for understanding how the sensor is situated and moves relative to a global coordinate system or reference frame.

Glossary

IntrinsicDescription
Sensor_size_pxThe resolution of the sensor in pixels, providing the width and height.
Sensor_size_mmThe physical dimensions of the sensor in millimeters, providing the width and height.
Pixel_size_mmThe size of each pixel on the sensor in millimeters.
Focal_length_mmThe focal length of the sensor's lens in millimeters.
Principal_point_pxThe coordinates of the principal point (typically the optical center) in pixels.
Aperture_mmThe diameter of the aperture in millimeters.

   

ExtrinsicDescription
Gnss_lockIndicates whether the Global Navigation Satellite System (GNSS) lock is acquired, affecting the accuracy of positional data.
Time_sThe time in seconds since a reference epoch, providing a temporal context.
Time_nsAdditional nanoseconds for finer temporal resolution.
InterpolatedIndicates whether the data point was interpolated (true) or directly measured (false).
AttitudeDescribes the sensor's orientation using quaternion components (w, x, y, z) and the reference frame.
PositionSpecifies the sensor's location in meters, relative to a reference frame.
VelocityProvides the sensor's velocity components in meters per second within a reference frame.
Angular_ratesIndicates the sensor's angular velocity in radians per second within a reference frame.