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Nodes

aruco_detect

aruco_detect detects the pose of aruco markers.

Subscribed Topics

/camera/compressed (sensor_msgs/CompressedImage)

• The images to be processed.

/camera_info (sensor_msgs/CameraInfo)

• The intrinsic parameters of the camera used to acquire the images.

Published Topics

/fiducial_vertices (fiducial_msgs/Fiducials)

• The vertices of detected fiducials.

/fiducial_transforms (fiducial_msgs/FiducialTransforms)

• The transforms showing the pose of the fiducials relative to the camera.

Parameters

There are two categories of ROS Parameters that can be used to configure the aruco_detect node: general and detection.

General parameters

Parameters

~dictionary (int, default: 7 (DICT_5X5_1000))

• The aruco dictionary to use. Possible values: 0 (DICT_4X4_50), 1 (DICT_4X4_100), 2 (DICT_4X4_250), 3 (DICT_4X4_1000), 4 (DICT_5X5_50), 5 (DICT_5X5_100), 6 (DICT_5X5_250), 7 (DICT_5X5_1000), 8 (DICT_6X6_50), 9 (DICT_6X6_100), 10 (DICT_6X6_250), 11 (DICT_6X6_1000), 12 (DICT_7X7_50), 13 (DICT_7X7_100), 14 (DICT_7X7_250), 15 (DICT_7X7_1000), 16 (DICT_ARUCO_ORIGINAL).

~fiducial_len (double, default: 0.14)

• The length of one side of a fiducial in meters, used by the pose estimation.

~fiducial_len_override (string, default: )

• A string expressing exceptions to fiducial_len. This can contain individual fiducial IDs, or ranges of them. Example: "1-10: 0.05, 12: 0.06" sets the length of fiducials 1 to 10 to 5cm and the length of fiducial 12 to 6cm.

~ignore_fiducials (string, default: )

• A string expressing fiducials to be ignored. This can contain individual fiducial IDs, or ranges of them. Example: "1-10, 12" ignores fiducials 1 to 10 and 12.

~publish_images (bool, default: false)

• If set, images will be published with the detected markers shown.

Detection parameters

The detector parameters used in the library are paramaters of the aruco_detect node. They can also be set via dynamic reconfigure.

~adaptiveThreshConstant (int, default: 7)

• Constant for adaptive thresholding before finding contours.

~adaptiveThreshWinSizeMax (int, default: 53)

• Minimum window size for adaptive thresholding before finding contours.

~adaptiveThreshWinSizeMin (int, default: 3)

• Maximum window size for adaptive thresholding before finding contours.

~adaptiveThreshWinSizeStep (int, default: 4)

• Increments from adaptiveThreshWinSizeMin to adaptiveThreshWinSizeMax during the thresholding.

~cornerRefinementMaxIterations (int, default: 30)

• Maximum number of iterations for stop criteria of the corner refinement process.

~cornerRefinementWinSize (int, default: 5)

• Minimum error for the stop criteria of the corner refinement process.

~cornerRefinementMinAccuracy (double, default: 0.01)

• Minimum error for the stop criteria of the corner refinement process

~doCornerRefinement (bool, default: true)

• Whether to do supbixel corner refinement.

~errorCorrectionRate (double, default: 0.6)

• Error correction rate respect to the maximum error correction capability for each dictionary.

~minCornerDistanceRate (double, default: 0.05)

• Minimum distance between corners for detected markers relative to its perimeter.

~markerBorderBits (int, default: 1)

• Number of bits of the marker border, i.e. marker border width.

~maxErroneousBitsInBorderRate (double, default: 0.04)

• Maximum number of accepted erroneous bits in the border (i.e. number of allowed white bits in the border).

~minDistanceToBorder (int, default: 3)

• Minimum distance of any corner to the image border for detected markers (in pixels).

~minMarkerDistanceRate (double, default: 0.05)

• minimum mean distance beetween two marker corners to be considered similar, so that the smaller one is removed. The rate is relative to the smaller perimeter of the two markers.

~minMarkerPerimeterRate (double, default: 0.1)

• Determine minumum perimeter for marker contour to be detected. This is defined as a rate respect to the maximum dimension of the input image.

~maxMarkerPerimeterRate (double, default: 4.0)

• Determine maximum perimeter for marker contour to be detected. This is defined as a rate respect to the maximum dimension of the input image.

~minOtsuStdDev (double, default: 5.0)

• Minimun standard deviation in pixels values during the decodification step to apply Otsu thresholding (otherwise, all the bits are set to 0 or 1 depending on mean higher than 128 or not).

~perspectiveRemoveIgnoredMarginPerCell (double, default: 0.13)

• Width of the margin of pixels on each cell not considered for the determination of the cell bit. Represents the ratio with respect to the total size of the cell.

~perspectiveRemovePixelPerCell (int, default: 8)

• Number of bits (per dimension) for each cell of the marker when removing the perspective.

~polygonalApproxAccuracyRate (double, default: 0.01)

• Number of bits (per dimension) for each cell of the marker when removing the perspective.