Marker Board Configuration Widget¶
This widget allows specifying parameters for different types of single markers or marker boards. Algorithms that use this widget may choose to activate any subset of the principally supported markers.
Depending on the board type, different target parameters can be set in the widget. In the following the supported board / marker types and their parameters are listed. Some of them provide access to the underlying marker detector parameters via hidden Detector parameters, which can be expanded by checking the respective checkbox.
To generate some of the markers refer to marker generation algorithm.
Single Markers¶
1. ArUco Marker¶
A single marker defined by the ArUco Library with following parameters:
- Marker Id: Numeric ID of the marker
- Dictionary: Dictionary of the markers. Can hold a value from 0 to 16.
- Marker size: Side length of the marker in the target unit (typically mm).
Optionally parameters for the internal OpenCV marker detector can be set when checking Detector Parameters. Those parameters are simply forwarded to OpenCV, the user is referred to the OpenCV cv::aruco::DetectorParameters Reference for a detailed explanation.
2. AprilTag Marker¶
A single marker defined by the AprilTags Visual Fiducial System with following parameters:
- Family: The marker family, can be one of the following values:
Tag16h5Tag25h9Tag36h10Tag36h11TagCircle21h7TagCircle49h12TagCustom48h12TagStandard41h12TagStandard52h13- Marker Id: Numeric ID of the marker
- Marker size: Side length of the marker in the target unit (typically mm).
3. STag Marker¶
A single marker defined by STag: A Stable Fiducial Marker System with following parameters:
- Library HD
- Marker Id: Numeric ID of the marker
- Diameter: Diameter of the marker in the target unit (typically mm).
Marker Boards¶
1. ArUco Board¶
A marker board with a grid of markers defined by the ArUco Library with following parameters:
- Grid Size: Number of markers in the horizontal and vertical direction.
- Cell size: Size of a single square marker element in the target unit (typically mm).
- Marker separation: Distance between the neighboring edges of the markers in the target unit (typically mm).
- Dictionary: Dictionary of the markers. Can hold a value from 0 to 16.
- Starting marker: The index of the first marker on the board
Optionally parameters for the internal OpenCV marker detector can be set whe checking Detector Parameters. Those parameters are simply forwarded to OpenCV, the user is referred to the OpenCV cv::aruco::DetectorParameters Reference for a detailed explanation.
2. ChArUco board¶
An alternative marker board using markers from the ArUco Library. Unlike in the ordinary ArUco board, here the markers are placed inside the white squares of a chessboard, thereby combining accurate homology detection using the markers with accurate corner detection for precise calibration and pose estimation. Following parameters are supported:
- Grid Size: Number of markers in the horizontal and vertical direction.
- Cell size: Size of a single square element in the target unit (typically mm).
- Marker size: Size of the inner marker of the marker cells in the target unit (typically mm).
- Dictionary: Dictionary of the markers. Can hold a value from 0 to 16.
- Starting marker: The index of the first marker on the board
Optionally parameters for the internal OpenCV marker detector can be set whe checking Detector Parameters. Those parameters are simply forwarded to OpenCV, the user is referred to the OpenCV cv::aruco::DetectorParameters Reference for a detailed explanation.
3. Chessboard¶
A board with a chessboard pattern with following parameters:
- Grid Size: Number of cells in the horizontal and vertical direction.
- Cell size: Size of a single element in horizontal and vertical direction in the target unit (typically mm).
- Corner refinement win size: Size of search window for refining initial detection in pixels.
4. Circle Board¶
- Grid Size: Number of circular chessboard elements in the horizontal and vertical direction.
- Diameter: Diameter of a single circle in the target unit (typically mm).
- Spacing: Distance between the centers of the neighboring cells in the target unit (typically mm).
- Symmetric: Specifies whether the pattern is symmetric. Asymmetric grids have an additional line of circles offset by half the circle spacing between every row of the symmetric pattern, see for instance here. The grid size in this case is the number of rows without the added offset rows times the number of markers in the first and the second (offset) row. The circle spacing is the distance between the symmetric circles.
5. April Tag Board¶
A a board of AprilTags Visual Fiducial System markers with following parameters:
- Family: The marker family, can be one of the following values:
Tag16h5Tag25h9Tag36h10Tag36h11TagCircle21h7TagCircle49h12TagCustom48h12TagStandard41h12TagStandard52h13- Grid Size: Number of markers in the horizontal and vertical direction.
- Marker size: Size of a single marker element in the target unit (typically mm).
- Marker separation: Distance between the neighboring edges of the markers in the target unit (typically mm).
See the following image for clarification of the target parameters.
