Vehicle-Camera Calibration
Calibration Homepage
This page lets users view, create, launch, and delete calibration datasets. Admins can manage users’ access to these datasets on this page.
Click on New Calibration to create a new calibration dataset.
Calibration selection
Select Vehicle-Camera Calibration to create a new dataset.
Calibration Instructions Page
Upon selecting Vehicle-Camera Calibration, the user is welcomed to the instructions page. Click on Get started to start the calibration setup.
Approach selection
Select the Terrain as Flat and approach as Target
Configuration
Vehicle configuration
For more details, click here
Camera Intrinsic Parameters
Intrinsic parameters for the camera are to be added here. Users have three options.
Users can use the Camera Intrinsic calibration tool to calibrate the results, save them to the profile, and then load them here. For more details, click here.
Users can also load the JSON file.
Users can manually enter the intrinsic parameters if they already have them.
Target configuration
Horizontal corners: Total number of inner corners from left to right. The blue dots shown in the above preview correspond to the horizontal corners.
Vertical corners: Total number of inner corners from top to bottom. The red dots shown in the above preview correspond to the vertical corners.
Square size: It is the length of the arm of the square in meters. The square size corresponds to the length of the yellow square highlighted in the preview.
Left padding: The distance from the leftmost side of the board to the left-most corner point in meters. Corresponds to the left blue line in the preview.
Right padding: The distance from the rightmost side of the board to the rightmost corner point in meters. Corresponds to the right blue line in the preview.
Top padding: The distance from the topmost side of the board to the topmost corner point in meters. Corresponds to the top red line in the preview.
Bottom padding: The distance from the bottom-most side of the board to the bottom-most corner point in meters. Corresponds to the bottom red line in the preview.
Upload files from the mounted camera
Detect target corners in images
Users can click on Detect corners to detect the corners in the target. This is an automated process, and our algorithm usually detects the corners in the image accurately.
Add target configuration for images
For each image, enter the following target configuration
Distance from Vehicle Reference Point (VRP) to Intersection Reference Point (IRP).
If the board is placed perpendicular to the ground and on the ground directly, the target height should be 0. If the the board is placed perpendicular to the ground, but above ground level, the target height should be the distance from the bottom edge of the board to the ground level. If the board is parallel to the ground, the target height is the thickness of the board itself.
Distance from Intersection Reference Point (IRP) to Target Reference Point (TRP).
Run Calibration
Users must click Run calibration to calculate the extrinsic parameters and error stats.
Visualizer
Visualize button shows the 3d representation of the car and its wheels, along with the camera center and its frustum.
Error stats
Users can use these error values to estimate the accuracy of the calibration results alongside visual confirmation. The closer the error stats to zero, the better the extrinsic parameters.
Translation Error: The distance between the centroids of the 3d projections of target corners and the target configuration in the Vehicle coordinate system.
Rotation Error: The angle between the planes formed from 3d projections of target corners and the target configuration in the Vehicle coordinate system.
Extrinsic Calibration Output
roll, pitch, and yaw are in degrees, and px, py, and pz are in meters.
vehiclePoint3D is the 3d coordinates of a point in the vehicle coordinate system.
imagePoint3D is the 3d coordinates of a point in the camera coordinate system.
Camera coordinates system
We currently show three different types of camera coordinate systems. The extrinsic parameters change according to the selected Camera coordinate system. The export option exports the extrinsic parameters based on the selected camera coordinate system.
Optical coordinate system: It's the default coordinate system that we follow.
ROS REP 103: It is the coordinate system followed by ROS. On changing to this, you can see the change in the visualization and the extrinsic parameters.
NED: This follows the north-east-down coordinate system.
Vehicle Coordinate Frame
The origin of the vehicle coordinate frame is the midpoint of the line joining the rear wheel centers on the ground.
X-axis points in the vehicle's forward direction
Y-axis towards the left of the vehicle and
Z-axis pointing upward
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