Streaming Data

One of the most important services provided by the BOW SDK is the ability to communicate with a robot’s components – its sensors and actuators – without needing to know the details of the underlying hardware.

In this tutorial we’ll be using the QuickConnect, CloseConnect and <channel>.Get commands to stream images from a robot’s camera (<channel>.Set will be covered in the next tutorial).

Take a look at the following to see what we're aiming for:

About the Application

The purpose of the application you will develop here is to enable users to visualise live camera data from their robots. The structure of the application is as follows:

Before we get stuck in:

If you are just browsing to get a sense of what's possible, take a look at the code online.

Running the Application

cd SDK-Tutorials/GettingStarted/StreamingData/Python

python main.py

Investigation

Once the tutorial is running you will be able to see the robot's vision modality being output to your screen via a CV2 window. This provides a live view of the (simulated) visual scene captured by your robot, which you can verify by interacting with the robot inside Webots and monitoring the output.

Let's take a closer look at the key parts of the code:

myrobot, error = bow_api.quick_connect(app_name="BOW Streaming Data", channels=["vision"])
if not error.Success:
    print("Failed to connect to robot", error)
    sys.exit()

while True:
    image_samples, err = myrobot.vision.get(True)
    if not err.Success:
        print(err.Description)
        continue

if len(image_samples.Samples) == 0:
    continue
show_all_images(image_samples)
 
j = cv2.waitKeyEx(1)
if j == 27:
    break