[Matplotlib-users] continuous plotting with mplot3d

Bret Foreman bret.foreman at gmail.com
Wed Apr 15 11:42:24 EDT 2020

I'm using Python 2.7 on Windows 10 in a Jupyter Notebook.

I have an external orientation sensor on a USB port. I want to periodically
poll that sensor at around 10Hz and update the orientation of a figure on
the screen with each new sample. The sensor returns a quaternion when
polled which I convert to a rotation matrix to rotate a 3D image array.
This all works fine.

My problem is getting mplot3d to update the displayed image dynamically
after each orientation sample. All I can get is a plot at the end of the
run, nothing updates while I'm sampling. How can I change this code to plot

Here's my code:

*import serial.tools.list_ports   # import serial moduleimport
threespace_api_mod_Bret as ts_apiimport numpy as npimport quaternionimport
matplotlib.pyplot as pltfrom mpl_toolkits.mplot3d import Axes3Dimport
timedef pack_quat_3space_array( array ):    return np.quaternion( array[3]
, array[0] , array[1] , array[2] )class SensorAnimation( object ):
  def __init__(self,commport):        # Create 3D axis        self.fig =
plt.figure()        self.ax <http://self.ax> = self.fig.add_subplot(111,
projection='3d')        # Initialize the 3space sensor        self.sensor =
ts_api.TSUSBSensor(commport)        #create the 3d image to rotate
zline = np.linspace(0, 15, 1000)        xline = np.sin(zline)        yline
= np.cos(zline)        # Put the 3d data into an array for rotation
self.image_array = np.array([xline,yline,zline])        # Draw the initial
image        self.ax.plot3D(xline, yline, zline, 'red')        #
plt.show(block=False)    def RefreshPosition( self , previous ):        if
self.sensor is not None:            rot_matrix =
          result = np.dot(rot_matrix,self.image_array)            if
previous is not None:                try:                    plt.cla()
          except Exception as e:                    print(e)
previous = self.ax.plot3D(result[0], result[1], result[2], 'green')
    # plt.pause(0.00001)            return previous    def Close( self ):
      if self.sensor is not None:            self.sensor.close()try:    #
Set up animation object    sanimate = SensorAnimation("COM5")    previous =
None    for i in range(20):        previous = sanimate.RefreshPosition(
previous )        time.sleep(0.1)    sanimate.Close()*

Bret Foreman
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