Generating AR tags.

Generating AR tags of varying size, resolution, and data/ID encoding.

Track individual AR tags.

Identifying and tracking the pose of individual AR tags, optionally integrating kinect depth data (when a kinect is available) for better pose estimates.

Track multiple AR tags.

Identifying and tracking the pose of "bundles" consisting of multiple tags. This allows for more stable pose estimates, robustness to occlusions, and tracking of multi-sided objects.

NOT WORKING.

Using camera images to automatically calculate spatial relationships between tags in a bundle.

Detecting individual tags

The node individualMarkers takes the following command line arguments:

The width in centimeters of one side of the black square marker border
marker_size

A threshold determining when new markers can be detected under uncertainty
max_new_marker_error

A threshold determining how much tracking error can be observed before an tag is considered to have disappeared
max_track_error

The name of the topic that provides camera frames for detecting the AR tags. This can be mono or color, but should be an UNrectified image, since rectification takes place in this package
camera_image

The name of the topic that provides the camera calibration parameters so that the image can be rectified
camera_info

The name of the frame that the published Cartesian locations of the AR tags will be relative to
output_frame

* If you are not using a kinect or do not desire to use depth data improvements, use individualMarkersNoKinect instead.

Detecting multi-tag bundles

The node findMarkerBundles takes the following command line parameters:

marker_size

max_new_marker_error

max_track_error

camera_image

camera_info

output_frame

A list of XML file names, one for each bundle you wish to detect.
bundle_files

* If you are not using a kinect or do not desire to use depth data improvements, use findMarkerBundlesNoKinect instead.

API for individual markers

visualization_marker (visualization_msgs/Marker)An rviz message. When subscribed to, displays colored square blocks at the location of identified AR tags. Also overlay these blocks in a camera image.

ar_pose_marker (ar_track_alvar/AlvarMarkers)A list of the poses of all the observed AR tags, with respect to the output frame.

Camera frame (from Camera info topic param) → AR tag frame Provides a transform from the camera frame to each AR tag frame, named ar_marker_x, where x is the ID number of the tag.