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AprilTags are an implementation of Augmented Reality Tags from Edwin Olson's APRIL Laboratory at the University of Michigan. They are visual markers designed for robust detection by machines. See the ARTag.net web site for basic information and alternative implementations of the augmented reality tag idea. Here are some YouTube demo videos. And here are the two 2004 technical reports by Mark Fiala describing his ARTag implementation: NRC-47166 and NRC-47419.

AprilTags Install Instructions

These instructions from Edwin Olson at the University of Michigan are for installing his April Tags package under Easy Peasy 1.5, but they should work on most Ubuntu Linux systems.

1. Install necessary packages.

sudo -s
apt-get install git git-core ant libjogl-java libjogl-jni 
apt-get install subversion gtk-doc-tools libglib2.0-dev libusb-1.0-0-dev

2. Install libdc1394 (camera support).

cd /usr/local
svn co https://libdc1394.svn.sourceforge.net/svnroot/libdc1394 libdc1394
cd libdc1394/trunk/libdc1394
autoreconf -i -s
./configure   # Make sure you see "IIDC-over-USB support: Enabled"
make install

3. Install lcm. Download the source from Google Code into /tmp, then:

cd /tmp
gunzip lcm-0.4.1.tar.gz
tar -xvf lcm-0.4.1.tar
cd lcm-0.4.1
make install

4. Install April.

cd /usr/local
git clone git://april.eecs.umich.edu/home/git/april.git
cd april/java
export CLASSPATH=/usr/share/java/jogl.jar:/usr/share/java/gluegen-rt.jar:\

5. Install shell script to run the TagTest demo.

cd /usr/local/april/bin
cat >tagtest <<EOF
export CLASSPATH=/usr/share/java/jogl.jar:/usr/share/java/gluegen-rt.jar:\
cd /usr/local/april/java
java -ea -server -Djava.library.path=/usr/local/april/lib april.tag.TagTest
chmod +x tagtest

To run the demo, type /usr/local/april/bin/tagtest.

Generating Some AprilTags

To generate .png files for each tag in the 36h11 family, use the following commands:

cd /usr/local/april/java
export CLASSPATH=/usr/local/april/java/april.jar
java april.tag.TagFamily april.tag.Tag36h11 /tmp/tag36h11

You can then use a program like gv to display /tmp/tag36h11/alltags.ps, or use gimp or display to show one of the .png files. A few sample tags are shown below.

The first four AprilTags in the 36h11 series.