apriltags
ROS wrapper for the Swatbotics C++ port of the AprilTag visual
fiducial detector.
The Swatbotics port uses OpenCV and CGAL for improved performance.
http://github.com/swatbotics/apriltags-cpp
The AprilTag system was originally developed by the April laboratory at the University of Michigan.
http://april.eecs.umich.edu/wiki/index.php/AprilTags
E. Olson, "AprilTag: A robust and flexible visual fiducial system", IEEE International Conference on Robotics and Automation (ICRA), 2011.
Installation
Install dependencies:
$ sudo aptitude install libcgal-dev
Clone this repo into your catkin workspace and build.
Print some AprilTags
Images of the default tag family can be found in tags/36h11.ps
To open this postscript file:
$ sudo apt-get install gv
$ gv 36h11.ps
Alternatively you can download images of the tags from here:
https://april.eecs.umich.edu/wiki/index.php/AprilTags
There are *.tgz files for each family, including a *.ps file with one tag per page.
Configuration
Edit the launch file apriltags.launch
Set the default tag file parameter
param name="~default_tag_size" value="0.046"
to be the width of the black square of the tags you printed out e.g. 46mm
If your webcam does not publish images to the default topic name, you may need to edit these 2 parameters:
remap from="~image" to="/camera/rgb/image_rect"
remap from="~camera_info" to="/camera/rgb/camera_info"
For the Kinect2, they should be set too:
remap from="~image" to="/kinect2/hd/image_color_rect"
remap from="~camera_info" to="/kinect2/hd/camera_info"
Usage
$ roslaunch apriltags apriltags.launch
To check if the node can detect your printed tag:
$ rostopic echo /apriltags/detections