images.py

This example can be found in examples\python\images.py. When the PST SDK has been installed through the PST Software Suite installer the examples can be found in the Development folder.

This example shows how to enable image transfer on the PST Tracker and how to use the PST SDK to retrieve images. Images are 8 bit grayscale and are stored as an array without memory alignment or padding.

"""Images example of the PST SDK
 
This example shows how to enable image transfer on the PST Tracker and how to use
the PST SDK to retrieve images. Images are 8 bit grayscale and are stored as an
unsigned byte array without memory alignment or padding.
 
Copyright PS-Tech B.V. All Rights Reserved.
"""
import context
import time
import sys
import pstech.pstsdk.tracker as pst
import pstech.pstsdk.errors as psterrors
 
# Control variable for main loop
running = True
 
# Number of data points to grab before application termination
max_samples = 100
 
# Global number of samples
samples = 0
 
"""Implementation of the pst.Listener class to receive tracking data."""
class MyListener(pst.Listener):
 
    """Implementation of a tracker data callback function
 
    Implementation of a tracker data callback function. The on_tracker_data
    function receives the data as soon as it becomes available.
 
    Args:
        tracker_data: Object containing tracking information retrieved from tracker
        status_message: Status message reported by the tracker.
 
    See Also:
        pstech.pstdk.trackerdata.TrackerData
        pstech.pstsdk.errors.EStatusMessage
    """
    def on_tracker_data(self, tracker_data, status_message):
        global samples
        global running
 
        if samples >= max_samples:
            running = False
 
        samples += 1
        # Do something here with the received data
 
"""Helper function to register the exit handler with the application"""
def register_exit_handler():
    if sys.platform.startswith("linux"):
        import signal
        signal.signal(signal.SIGTERM, exit_handler)
        signal.signal(signal.SIGHUP, exit_handler)
        signal.signal(signal.SIGQUIT, exit_handler)
        signal.signal(signal.SIGINT, exit_handler)
    elif sys.platform.startswith("win"):
        import win32api
        win32api.SetConsoleCtrlHandler(exit_handler, True)
 
"""Implement the exit handler to shut-down the PST Tracker connection on application termination."""
def exit_handler(*args):
    global running
    pst.Tracker.shutdown()
    running = False
    return True
 
def main():
    if(len(sys.argv) < 2):
        print("\nConfiguration Error: A camera configuration file needs to be specified. This file can be found in the Redist folder of your installation. "
                "See the documentation of the Python bindings for more information.")
        exit(0)
 
    # Register exit_handler for proper shutdown
    register_exit_handler()
 
    try:
        # Use Context Manager to prevent improper Tracker shutdown on errors.
        # Create an instance of the Tracker object using the default configuration path and file names.
        with pst.Tracker("", "","", sys.argv[1]) as tracker:
 
            # Print version number of the tracker server being used.
            print("Running PST Server version " + tracker.get_version_info())
 
            # Create listener with callback functions for data and/or mode updates.
            listener = MyListener()
            
            # Register the listener object to the tracker server.
            tracker.add_tracker_listener(listener)
 
            # Start the tracker server.
            tracker.start()
 
            # Perform a system check to see if the tracker server is running OK and print the result.
            print("System check: " + str(tracker.system_check()))
            print("***************************\n")
 
            # Set the frame rate to 60 Hz.
            tracker.set_framerate(60)
            print("Current frame rate: " + str(tracker.get_framerate()))
 
            # In order to start receiving images, enable image transfer. When image transfer is disabled,
            # the vector of images returned by Tracker.get_image() will be empty.
            tracker.enable_image_transfer()
 
            # The standard PST trackers will run at a reduced frame rate of 30 Hz when image transfer is enabled.
            # However, since this frame rate is temporary for as long as image transfer is enabled, that frame rate
            # will not be reported as the current frame rate.
            print("Enabled image transfer. Current frame rate: " + str(tracker.get_framerate()))
            print("***************************\n")
 
            # Try to capture 100 images.
            for i in range(100):
                # Try to get the last grabbed image.
                # Note that enabling image transfer takes some time. While image transfer is being enabled,
                # the images list in the Image object will be empty.
                image = tracker.get_image()
 
                if image is not None:
                    print("Retrieval operation successful!\n")
                    print("Retrieved " + str(len(image.images)) + " image(s) of size: " + str(image.width) +  " X " + str(image.height) + "\n")
                    # Do something with the image
                else:
                    print("Retrieval operation unsuccessful!\n")
 
                # Don't request images too fast, wait for around 1/60 seconds.
                time.sleep(0.016)
 
            # Wait for 5 seconds, since this is > 4 seconds, image transfer will be disabled automatically.
            print("Waiting 5 seconds for image transfer to automatically be disabled...\n")
            time.sleep(5)
 
            # Try to grab one image. Since image retrieval timed out, it should return an empty image vector.
            image = tracker.get_image()
            if image is not None:
                print("Retrieval operation successful!\n")
                print("Retrieved " + str(len(image.images)) + " image(s) of size: " + str(image.width) +  " X " + str(image.height) + "\n")
            else:
                print("Retrieval operation unsuccessful!\n")
 
            while running:
                time.sleep(0.1)
 
    except psterrors.TrackerError as err:
        # Catch TrackerError and print error messages.
        print(err.message)
 
if __name__ == "__main__":
    main()