In this lecture, we will learn about visualization tools we can use with ROS to the tools and features
I'm going to show are also available in Ross one.
The first tool we will use is called Orvis, which is a3d visualization tool to run it.
Let's open a new terminal and run our VIZ two.
It opens and we can see a series of panels, so go ahead and maximize the window.
This main dark colored section is actually a3d view window.
If we had any sensor, data, localization data or robot transform data, we would be able to see it
here.
One of the things I like to use it in the past was for visualizing three D LiDAR data, which is a point
cloud showing the distance surfaces are from the lidar.
The left pane is where we can add and manage our sensors and other visualization parameters.
So click on the add button.
We'll open up this dialog window where we can either add a sensor by type or a corresponding topic name.
Now, I know this doesn't seem like much now, but we will utilize this tool more once we start working
with the simulation and have more 3D data to process within this viewport window.
So I'll go ahead and close this and I will close without saving.
And the next visualization tool we're going to go over is called our q T, where our stands for ROS
and Q.
RT is a popular user interface framework.
So in essence, this tool is meant for helping users interact and visualize ROS data.
So it opens up and it's just a blank window and it just says RCT is a gooey framework that is able to
load various plug ins.
So in order to use this tool to the best, you would go into the plugins tab and here you'll have various
plug ins which you can utilize depending on what functionality you're looking for to interact with your
RAS systems to help showcase the features.
In this tool, I will use a back file to playback sensor data from a robot, so I'll go ahead and open
up our terminal, put a new terminal tab This is the same file from the previous lecture, so if you
have it downloaded already, no need to redownload it.
So I'll go ahead into my downloads folder.
So we see the back file, so I'll just go ahead and do Ros to bag play dash L to loop it and marine
surface vehicle bay.
All right.
The bag is playing.
Now, if we go back to our RCT window, I can go ahead and open up some plug in.
So the first plug in we're going to go over is the topic monitor plug in.
So we see a series of topics.
If I want to see the data coming over a topic, I can click on the dropdown arrow and then select the
checkbox to start subscribing to the data coming in.
So here we can see things like the latitude and longitude coming in the same way we would do it from
the terminal, but now in this user interface and we can do this for multiple topics at the same time.
So here now we're subscribed to the fixed topic as well as the IMU data, and we can see it updating
like so on.
If you ever want to just stop subscribing, you can uncheck it.
And now you're no longer subscribed to that information.
It says not monitored.
So go ahead and collapse that.
So as you can see, this plugin is an interactive way of doing ROS to topic lists and ros Su topic echo
through a user interface in the actions Project Walkthrough video.
You saw me utilize this RCT tool to create a publisher in order to publish my robots coordinates.
I did that with the message publisher plugin.
So whenever you open multiple plug ins, it'll open in a separate window and you can feel free to rearrange
the windows to match your configuration that you want.
I'll go ahead and put this back down here.
And so as you saw me use it in the previous lectures, you could create a topic name such as test topic.
Give it a particular message type.
So I'll just grade float.
Add it to our list of existing topics.
So these ones were here from previous lectures.
If you want to remove them, you can just hit the minus sign.
And then if I wanted to echo this topic right now it's 0.0.
Let's change to something like 1.5.
And then if I want to publish this, I can go ahead and hit it like that.
We see it up here in our topic monitor, and if I go ahead and subscribe to it, we see it says 1.5
and I can publish different values like 3.0 and we see it changes in the topic.
Monitor Again, this all corresponds with our standard RAR two commands that we can use in terminal.
So the same ROS two topic echo slash test topic.
And we see that 3.0 value.
So again, I can change it one more time just to show.
All right.
4.5 and we get the 4.5 when echoing the data in terminal.
All right.
I'll go ahead and stop publishing that and I'll go ahead and close this plugin for right now.
Another useful feature for checking interactions between nodes is the Node graph plugin.
All right.
So I'll go ahead and slide this over and we can zoom in using the scroll wheel.
And right now we only are showing nodes.
So we see the ROS bag to player node, but I can actually go ahead and do notes topic and I'll just
choose the active ones.
And here we see the Rosberg player is publishing to fix, and that's because here in our topic Monitor
we're subscribing to it.
So I can go ahead and try this out in terminal one more time.
So now I'm echoing the IMU data, and if I refresh the node graph, we now see node graph where the
node raw player is publishing to IMU, IMU data topic, which is being subscribed to and it's currently
active.
All right.
So I'll go ahead and stop that echoing.
Close this terminal.
And again, if I refresh it, it'll update as such.
So besides the node graph, there's actually a topic graph in which we can actually visualize information
as it's coming in on a plot.
So I'll go ahead and open that.
Go ahead and unsubscribe from my fixed topic right now.
Give a little bit more room to the plot, and the topic I'm interested in will be the IMU data and we'll
take a look at the linear acceleration.
So when you utilize a valid topic, name or subtopic type in which it can graph, you'll see the plus
arrow be available to click.
So here it says three plausible fields in IMU data, linear acceleration, and that's for the x, Y
and Z, which we will go ahead and see if I go ahead and hit the plus and we see it plotting in real
time.
So naturally we see the Z is a lot higher because of the way the IMU is mounted.
It's getting that 9.8 meters a second squared of acceleration from gravity.
And so right now it's auto scrolling.
You can always turn that off.
And once we reach the end of the bag file and it loops, you'll actually notice the graph stops producing
and you just go ahead and clear the plot and it'll go ahead and restart from the beginning.
That's only because we technically went back in time as part of the bag file looping.
If you ever want to stop this, you just go ahead and hit the minus sign and remove the particular topics
you want to stop graphing or all of them.
And last but not least, one of the greatest plug ins of interest that my students like to use is heading
over to the visualization and the image view.
All right.
So if I go ahead and expand this a bit.
I'll actually go ahead and close our topic monitor for right now.
We are greeted with this gradient screen.
This is where the images will show based off the topic we select.
So if we hit the refresh button, we can actually see a list of available topics which has image streams
available to us.
So in this case we have a USB camera with compressed images going through.
So if I go ahead and click on that, we can actually see the front camera of this autonomous surface
vehicle that was being used in this bag file.
All right.
I hope that was a good introduction to the RCT tool.
Feel free to check out the plug ins and see how they can be helpful to interact with your system.
Basically, whenever you want to visualize three D data or localization information about a robot,
you would most likely be using RVs.
While our TX acts like a dashboard to help you view and interact with your Ross data.
With that, let's get to working on simulations.