continuous plotting with mplot3d

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continuous plotting with mplot3d

Bret Foreman

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 dynamically?

Here's my code:

import   # import serial module
import threespace_api_mod_Bret as ts_api
import numpy as np
import quaternion
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import time

def 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.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, yline, zline, 'red')

    def RefreshPosition( self , previous ):
        if self.sensor is not None:
            rot_matrix = quaternion.as_rotation_matrix(pack_quat_3space_array(sensor.getTaredOrientationAsQuaternion()))
            result =,self.image_array)
            if previous is not None:
                except Exception as e:
            previous =[0], result[1], result[2], 'green')
            # plt.pause(0.00001)
            return previous

    def Close( self ):
        if self.sensor is not None:

    # Set up animation object
    sanimate = SensorAnimation("COM5")
    previous = None
    for i in range(20):
        previous = sanimate.RefreshPosition( previous )

Bret Foreman

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