Below are the Steps to create the project as shown in the video

Step 1

• Head to ROS Development Studio and create a new project.
• Provide a suitable project name and some useful description. (We have named the project )
• Load/Open the project (this will take few seconds).
• Open Tools > Shell and run following commands

$ echo $ROS_MASTER_URI

Note the result of the above command, it should have the following format http://<ip>:<port>. The following image shows a representational value

The specific values shown in the image are \<ip>=10.8.0.1 and \<port>=11311.

Step 2

• The ip we just saw is also referred as hostname and it denotes the address of the computer running the roscore program.
• To understand better, lets run a ros application

$ roslaunch openni_launch openni.launch

When the above command executes, it will launch the openni project. First of all ros master will be run (as shown) and once the ros master is ready other nodes are loaded. Note that there is only one ros master, however any number of nodes can exist.

Step 3

Next we can see how to change the ROS_MASTER_URI. The simplest way to change ROS_MASTER_URI is by editing the .bashrc file. This file is a system file and thus hidden by default, we will modify its content using the vi editor. Use the following command to start editing the .bashrc file (located in home directory)

$ vim ~/.bashrc

The following line is responsible for assigning the ros master ip

export ROS_MASTER_URI=http://10.8.0.1:11311

We can modify this line to use any other ip address. For reflecting the changed ip we will need to load this bash file. Use the following command to do so

$ source ~/.bashrc

Once we have sourced the bashrc file, we will see the changed ros master uri when launching ros project.

Follow these steps to recreate the project as shown in the video

• Go to Robot Ignite Academy. You will need to signup if you have not registered already.
• In the home page, choose the course ROS Autonomous Vehicles 101 in the Advanced Courses category

• Once you start the course, you will be greeted with the workspace like following (note: it will take a while to load the full page)

Now we will use the rosrun command to start a rqt_image_view node. Enter the following command in one of the SHELLS

rosrun rqt_image_view rqt_image_view

• In order to see the visualisation we need to open the Graphical View by clicking on the graphical tool icon shown in the previous image. The graphical view opens in a new tab like follows

Since the model we are using (autonomous car) has many camera topics, we will need to choose one from the drop-down in the graphical view (shown in image).

• rosrun essentially lets us start a single node. However, in many cases one needs to start multiple nodes at a time. To do this (launching multiple nodes simultaneously) we have launch file and the roslaunch command. Lets create such a launch file to launch xyz. Navigate to ~/catkin_ws/tuto/src/ and create a launch directory and create a file inside this directory launch_rviz.launch. Use the following command to achieve this
  

  $ cd ~/catkin_ws/src/tuto/ $ mkdir launch
  $ cd launch
  $ touch launch_rviz.launch

Next, we will add the following content to this file using the cloud9 editor. Use the editor to browse to the file and then double click on the file name to open it (as shown in image)

The code for the launch file as follows

<launch> 
    <node name="cam1" pkg="rqt_image_view" type="rqt_image_view" /> 
    <node name="cam2" pkg="rqt_image_view" type="rqt_image_view" /> 
</launch>

Now we will launch this launch file with the following command

roslaunch tuto launch_rviz.launch

On executing the above command we will see two new nodes appear and two rqt_image_view appear in the Graphical window tab. That’s all for this video.