cameraInfo QML Value Type

This message defines meta information for a camera. It should be in a camera namespace on topic "camera_info" and accompanied by up to five image topics named:. More...

Properties

• binningX : uint32_t
• binningY : uint32_t
• d : list<double>
• distortionModel : string
• header : header
• height : uint32_t
• k : list<double>
• p : list<double>
• r : list<double>
• roi : regionOfInterest
• width : uint32_t

Detailed Description

• image_raw - raw data from the camera driver, possibly Bayer encoded
• image - monochrome, distorted
• image_color - color, distorted
• image_rect - monochrome, rectified
• image_rect_color - color, rectified

The image_pipeline contains packages (image_proc, stereo_image_proc) for producing the four processed image topics from image_raw and camera_info. The meaning of the camera parameters are described in detail at http://www.ros.org/wiki/image_pipeline/CameraInfo.

The image_geometry package provides a user-friendly interface to common operations using this meta information. If you want to, e.g., project a 3d point into image coordinates, we strongly recommend using image_geometry.

If the camera is uncalibrated, the matrices D, K, R, P should be left zeroed out. In particular, clients may assume that K[0] == 0.0 indicates an uncalibrated camera.

Image acquisition info

cameraInfo is a structured value type usable in QML. It maps directly to the sensor_msgs::msg::CameraInfo ROS 2 message type.

Construct a cameraInfo in QML by assigning a JavaScript object whose keys are its component properties, or by setting those properties individually.

See also CameraInfoPublisher and CameraInfoSubscriber.

Property Documentation

binningX : uint32_t

Binning refers here to any camera setting which combines rectangular

neighborhoods of pixels into larger "super-pixels." It reduces the resolution of the output image to (width / binning_x) x (height / binning_y). The default values binning_x = binning_y = 0 is considered the same as binning_x = binning_y = 1 (no subsampling).

binningY : uint32_t

d : list<double>

The distortion parameters, size depending on the distortion model.

For "plumb_bob", the 5 parameters are: (k1, k2, t1, t2, k3).

distortionModel : string

The distortion model used. Supported models are listed in

sensor_msgs/distortion_models.hpp. For most cameras, "plumb_bob" - a simple model of radial and tangential distortion - is sufficent.

header : header

Time of image acquisition, camera coordinate frame ID

height : uint32_t

The image dimensions with which the camera was calibrated.

Normally this will be the full camera resolution in pixels.

k : list<double>

Intrinsic camera matrix for the raw (distorted) images.

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

Projects 3D points in the camera coordinate frame to 2D pixel coordinates using the focal lengths (fx, fy) and principal point (cx, cy).

p : list<double>

Projection/camera matrix

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

By convention, this matrix specifies the intrinsic (camera) matrix of the processed (rectified) image. That is, the left 3x3 portion is the normal camera intrinsic matrix for the rectified image. It projects 3D points in the camera coordinate frame to 2D pixel coordinates using the focal lengths (fx', fy') and principal point (cx', cy') - these may differ from the values in K. For monocular cameras, Tx = Ty = 0. Normally, monocular cameras will also have R = the identity and P[1:3,1:3] = K. For a stereo pair, the fourth column [Tx Ty 0]' is related to the position of the optical center of the second camera in the first camera's frame. We assume Tz = 0 so both cameras are in the same stereo image plane. The first camera always has Tx = Ty = 0. 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 onto the rectified image is given by:

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

x = u / w y = v / w This holds for both images of a stereo pair.

r : list<double>

Rectification matrix (stereo cameras only)

A rotation matrix aligning the camera coordinate system to the ideal stereo image plane so that epipolar lines in both stereo images are parallel.

roi : regionOfInterest

Region of interest (subwindow of full camera resolution), given in

full resolution (unbinned) image coordinates. A particular ROI always denotes the same window of pixels on the camera sensor, regardless of binning settings. The default setting of roi (all values 0) is considered the same as full resolution (roi.width = width, roi.height = height).

width : uint32_t