====== Tag Recognition Using Webcam ======

===== Introduction ===== 

We will learn to do tag recognition using your web-cam. Before we continue any further lets make sure you have the necessary package.  Open up a terminal and enter :

  roscd ar_recog

This should take you to the folder of the package "ar_recog". If you don't have the package please download it from the brown repository. Open up a terminal and enter the following line:

  svn checkout http://brown-ros-pkg.googlecode.com/svn/trunk/brown-ros-pkg-read-only

===== Print out a tag =====

We obviously need an image tag before we test the code.

Step 1:Go to the folder of the package "ar_recog" 
Step 2:open up the file "Ar_patts.zip". 
Step 3:Print out your desired image tag.

===== Test the code =====

1. Enter the following commands each in a new terminal.

  roscore
  rosrun gscam gscam

2.Open up a new terminal and enter the lines one after the other :

  roscd ar_recog
  cmake .
  rosmake

Make sure you get 0 failures for rosmake.

  cd bin
  rosparam set aov .67
  rosrun ar_recog ar_recog image:=/gscam/image_raw

Enter the following commands each in a new terminal:

  rosrun image_view image_view image:=/gscam/image_raw
  rosrun image_view image_view image:=/ar/image

===== Testing the image tag =====

Considering the fact that you have a printed image tag.
Hold it in-front of the camera in such a way that your fingers don't touch the surface of the tag.
I pasted the tag on to the surface of a box lid.

{{dylanw:imagetag.jpg}}\\ 

When you test with the image tag you should see a green line outlining the image tag.

{{dylanw:image1.png}}\\ 

{{dylanw:image2.png}}\\ 

===== Getting the coordinates =====

To have a deeper insight of the image tag being recognized open up a terminal and enter:

  rostopic echo  /tags

This shows you the movement of image tag  along the x,y,z axes.