CameraCalibration

Panel Support

CameraCalibration is used in the 3D Panel and Image Panel.

Field Definitions

Field Name	Type	Description
timestamp	time	Timestamp of the calibration data
frame_id	string	Reference coordinate system of the camera. The origin of this coordinate system is the optical center of the camera, with +x pointing to the right in the image, +y pointing down, and +z pointing into the image plane.
width	uint32	Image width
height	uint32	Image height
distortion_model	string	Distortion model name
D	float64[]	Distortion parameters
K	float64[9]	Intrinsic matrix (3x3 row-major storage)
R	float64[9]	Rectification matrix (only used for stereo cameras, 3x3 row-major storage)
P	float64[12]	Projection/camera matrix (3x4 row-major storage)

distortion_model

• plumb_bob: Parameters are k1, k2, p1, p2, k3
• rational_polynomial: Parameters are k1, k2, p1, p2, k3, k4, k5, k6

This model is based on OpenCV's pinhole camera model and is consistent with the implementation in ROS.

K Intrinsic Matrix

K is a 3x3 row-major matrix for the original (uncorrected) image.

It uses the focal lengths (fx, fy) and principal point (cx, cy) to project 3D points in the camera coordinate system to 2D pixel coordinates.

    [fx   0  cx]
K = [ 0  fy  cy]
    [ 0   0   1]

R Rectification Matrix

Rotation matrix that aligns the camera coordinate system with the ideal stereo image plane, making epipolar lines in the two stereo images parallel.

P Projection Matrix

    [fx'  0   cx'  Tx]
P = [ 0   fy' cy'  Ty]
    [ 0    0    1    0]

This matrix specifies the intrinsic (camera) matrix of the processed (rectified) image. That is, the left 3x3 part is the normal camera intrinsic matrix for the rectified image.

It uses the focal lengths (fx', fy') and principal point (cx', cy') to project 3D points in the camera coordinate system to 2D pixel coordinates — these may differ from the values in K.

For a monocular camera: Tx = Ty = 0, and typically R is the identity matrix with P[1:3,1:3] = K.

For a stereo pair, the fourth column [Tx Ty 0]' relates to the position of the optical center of the second camera in the coordinate system of the first camera. We assume Tz = 0 so that the two cameras are in the same stereo image plane. Tx is always 0 and Ty = 0 for the first camera. For the right (second) camera of a horizontal stereo pair, Ty = 0 and Tx = -fx' * B, where B is the baseline between the cameras.

Given a 3D point [X Y Z]', the projection (x, y) of the point on the rectified image is calculated as:

[u v w]' = P * [X Y Z 1]'
x = u / w
y = v / w

This applies to both images of a stereo pair.

References

coScene's schema types are framework-independent and can be implemented using any supported message encoding format.

Encoding Format	Schema Name
ROS 1	foxglove_msgs/CameraCalibration
ROS 2	foxglove_msgs/msg/CameraCalibration
JSON	foxglove.CameraCalibration
Protobuf	foxglove.CameraCalibration
FlatBuffers	foxglove.CameraCalibration
OMG IDL	foxglove::CameraCalibration

Note: You must use the schema names specified above for coScene to recognize them correctly.